Suto et al.2009

Taxonomy of middle Eocene diatom resting spores and
their allied taxa from the central Arctic Basin
Itsuki Suto,1 Richard W. Jordan2 and Mahito Watanabe3
1
Department of Earth and Planetary Sciences, Graduate School of Environmental Studies,
Nagoya University, Chikusa, Nagoya 464-8601, Japan
Department of Earth and Environmental Sciences, Faculty of Science,
Yamagata University, Kojirakawa-machi 1-4-12, Yamagata 990-8560, Japan
2
3
Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of
Advanced Industrial Science and Technology (AIST), Central 7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan
email: [email protected]
email: [email protected]
email: [email protected]
ABSTRACT: In the late summer of 2004, Integrated Ocean Drilling Program (IODP) Expedition 302, also called the Arctic Coring Expedition (ACEX), successfully drilled the first deep boreholes on the Lomonosov Ridge in the central Arctic Ocean. The well preserved
fossil diatoms used here are from biosiliceous Unit 2 in Holes 2A and 4A of middle Eocene age. In the lower part of Unit 2, resting spores
occurred abundantly with other fossil diatoms. 25 diatom resting spore taxa and five allied vegetative cell taxa are described in this study
of ACEX samples. Moreover 11 diatom taxa which did not occur in these sediments are also described for comparison with the Eocene
Arctic resting spores. Their biostratigraphic ranges are also indicated. 10 of the resting spore species which occur in the ACEX samples
had already appeared during the late Cretaceous while the rest of them appeared in Eocene. 21 of 25 (84%) resting spore taxa became extinct during the middle Eocene to early Oligocene. Most resting spore taxa described in this study do not belong to Chaetoceros resting
spores because they lack a single ring of puncta on the hypovalve mantle that characterizes the resting spores of Chaetoceros and became
extinct before Oligocene, therefore it is clear that Chaetoceros did not flourish in the middle Eocene in the Arctic Ocean. Other diatom
genera that produced resting spores such as Pterotheca and Pseudopyxilla, might have prospered before the Eocene/Oligocene boundary, although their vegetative cells are unknown so far. Since some Chaetoceros resting spore taxa are reported in this study, most coastal
regions experienced regular seasonal environmental change, which benefitted genera such as Pterotheca, Pseudopyxilla and
Odontotropis, but also there might have been some patchy coastal upwelling regions with nutrient depletion and sporadic supplies where
Chaetoceros may have survived. The abundant dinoflagellate cysts preserved in middle Eocene ACEX cores provide evidence of stable
conditions before the Eocene/Oligocene boundary. The resting spore ecology of most resting spore taxa before the Eocene may have
been similar to that of dinoflagellate cysts rather than that of Chaetoceros resting spores after the Oligocene.
INTRODUCTION
Fossil diatoms have been reported in many oceanic sediment
cores, especially those of the DSDP (Deep-Sea Drilling Project)
and ODP (Ocean Drilling Program), as biostratigraphic markers in various geological epochs, particularly Miocene (e.g.
Yanagisawa and Akiba 1998). Although extensive studies of
fossil Arctic diatoms in diatomites (e.g. Strelnikova 1974,
Barron 1985, Medlin and Priddle 1990, Tapia and Harwood
2002) have been reported, these studies only documented the
late Cretaceous or Holocene and Pleistocene diatoms, and since
then there have been few papers on Eocene Arctic diatoms.
Moreover, the taxonomy of fossil diatom resting spores has
been neglected.
Some coastal planktonic diatoms survive unfavorable environmental conditions as resting spores. The model of Gran (1912)
proposed that resting spores were benthic resting stages, and
subsequent studies showed that they are formed in response to
nutrient depletion, darkness and low temperature (e.g. Kuwata
et al. 1993, Oku and Kamatani 1995, 1997, 1999, McQuoid and
Hobson 1996). Resting spores having thick silicified valves and
lacking areolae are preserved frequently as fossils in nearshore
sediments. The occurrences of fossil diatom resting spores are
concentrated in coastal waters and are most common in temper-
ate and boreal waters, but are also found in polar and tropical regions (e.g. Schrader 1978, Leventer 1991), especially in
upwelling areas (Hargraves 1984) and reported from ancient
sediments, extending back to the Cretaceous (Hanna 1927b,
Ross and Sims 1974). Fossil diatom resting spores have been
used as paleoclimatic, especially upwelling, indicators. Suto
(2006a) proposed that the increase in diversity and abundance
of Chaetoceros resting spores from the late Eocene to early
Oligocene in the Norwegian Sea indicated a change from a stable environment with regular seasonal supply of nutrients to an
unstable one with depletion and sporadic supply. He also mentioned that Chaetoceros might have established itself as the
main primary producer in the Oligocene Norwegian Sea, replacing dinoflagellates and/or nannoplankton which had been
the main producers till the late Eocene because their diversities
decreased across the boundary (Falkowski et al. 2004).
In the late summer of 2004, Integrated Ocean Drilling Program
(IODP) Expedition 302, also known as the Arctic Coring Expedition (ACEX), successfully drilled the first deep boreholes in
the central Arctic Ocean, penetrating a ~430m-thick package of
sediment on the Lomonosov Ridge (Backman et al. 2005a, b,
Moran et al. 2006) (Text-figure 1). The well preserved Eocene
fossil diatoms used here are from biosiliceous Unit 2 in Holes
micropaleontology, vol. 55, nos. 2-3, pp. 259-312, text-figures 1-9, plates 1-13, 2009
259
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
cies is separated from Peripteropsis norwegica Suto (2005b) by
lacking branched thin and wide processes.
Stratigraphic and geographic distributions: This species occurred in middle Eocene sediments from IODP Leg 302 Sites
2A and 4A in the central Arctic Ocean.
Remarks: This species does not appear to belong to the fossil
resting spore morpho-genus Peripteropsis of extant
Chaetoceros because of the absence of a ring of puncta on the
hypovalve margin.
Porotheca danica (Grunow) Fenner 1994
Plate 7, figures 1-28
Porotheca danica (Grunow) FENNER 1994, p. 114, pl. 4, figs. 16, 17;
pl. 15, figs. 1-6.
Basionym: Stephanogonia (Pterotheca?) danica GRUNOW in VAN
HEURCK 1880-1885, pl. 83 bis., figs. 7, 8.
References: Stephanogonia danica GRUNOW 1866, p. 146. – CLEVEEULER 1951, Handl. 2: 1, p. 110, figs. 232a, b. – HOMANN 1991, p.
141, pl. 55, figs. 7, 9-16.
Synonymy: Pyxilla carinifera var. russica PANTOCSEK 1905, Bd. 3,
pl. 35, fig. 491; Bd. 3, pl. 29, fig. 423.
Pterotheca danica GRUNOW, HANNA 1927a, p. 119, pl. 20, fig. 11. –
PROSCHKINA-LAVRENKO 1949, p. 203, pl. 75, fig. 9. – HAJÓS
1976, p. 829, pl. 16, figs. 12-15. – GOMBOS 1977, p. 596, pl. 23, fig.
5. – LEE 1993, p. 42, pl. 3, fig. 4. – DELL’AGNESE and CLARK
1994, fig. 9.11.
Pterotheca cf. aculeifera Grunow sensu HAJÓS and STRADNER 1975,
p. 933, pl. 28, figs. 1, 2 nec pl. 12, fig. 6.
Pterotheca carinifera Grunow in VAN HEURCK sensu MCCOLLUM
1975, p. 535, pl. 10, fig. 4 nec pl. 16, figs. 6, 7.
Pterotheca danica (Grunow) FORTI 1909, p. 13. – GOMBOS 1983, p.
570, pl. 3, fig. 9. – GOMBOS and CIESIELSKI 1983, p. 603, pl. 13,
figs. 1-3, 9. – BARRON et al. 1984, p. 156, pl. 8, fig. 10. – BALDAUF
1985, p. 464, pl. 12, figs. 8, 9. – HARWOOD 1988, p. 86, fig. 18.12. –
DESIKACHARY and SREELATHA 1989, p. 218, pl. 100, figs. 1, 2,
5.
Pterotheca major JOUSÉ 1955, p. 101, text-fig. 1; pl. 6, fig. 2. –
GOMBOS 1983, p. 570. – GOMBOS and CIESIELSKI 1983, p. 603,
pl. 13, figs. 6-8. – HARWOOD 1988, p. 86, fig. 18.16.
Pterotheca spada TEMPÈRE et BRUN sensu GOMBOS and
CIESIELSKI 1983, p. 603, pl. 13, figs. 4, 5.
Pterotheca (Grunow) FORTI sensu HARGRAVES 1984, p. 71, figs.
14-16.
Pterotheca carinifera (Grunow in Van Heurck) FORTI sensu HARWOOD 1988, p. 86, fig. 18.6.
Stephanogonia novazelandica Grunow sensu DESIKACHARY and
SREELATHA 1989, p. 228, pl. 100, figs. 3, 4.
Pyxilla? carinifera Grunow sensu HOMANN 1991, p. 139, pl. 55, fig. 6
nec figs. 1-5, 8.
Pterotheca carinifera Grunow sensu HARWOOD and BOHATY 2000,
p. 93, pl. 3, fig. t; pl. 9, fig. o.
Emended description: Epivalve convex, cylindrical with a high
mantle, diameter 13-45µm, transapical axis 30-65µm. The central part of epivalve face protracted forming a hollow tube with
a flat top. Epivalve surface generally structured by seven to
TEXT-FIGURE 8
Geographic and stratigraphic distribution of Trochosira spinosa Kitton.
1-25. Trochosira spinosa
15 Fur Formation, Denmark (Fenner 1994);
1-17. Reported as Trochosira spinosa.
1 Mors, Denmark (Kitton 1871);
16 ODP Hole 908A (Scherer and Koç1996);
2 Mors Formation, Denmark (Van Heurck 1880-1885);
3 Lower course of the Anadyr River, Russia (Sheshukova-Poretskaya 1967);
4 DSDP Site 173 (Schrader 1973a);
5 west Kazakhstan (Glezer et al. 1974);
6 DSDP Site 337 (Schrader and Fenner 1976);
7 DSDP Site 338 (Schrader and Fenner 1976);
8 DSDP Site 339 (Schrader and Fenner 1976)
9 DSDP Site 343 (Schrader and Fenner 1976);
10 DSDP Site 338 (Dzinoridze et al. 1978);
11 DSDP Site 339 (Dzinoridze et al. 1978);
12 DSDP Site 340 (Dzinoridze et al. 1978);
13 Hawthorn Formation, South Carolina (Abbott and
Andrews 1979);
14 Mors and Fur Formations, Denmark (Homann 1991);
274
17 DSDP Site 338 (This study).
18, 19. Reported as Trochosira spinosus.
18 Jutland, Denmark (Sims 1988);
19 Cape Roberts Project, Antarctica (Scherer et al.
2000).
20. Reported as Trochosira spinosa?
20 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
21, 22. Reported as Trochosira ornata.
21 Jutland, Denmark (Van Heurck 1880-1885);
22 Fur Formation, Denmark (Fenner 1994).
23. Reported as Sceletonema ornatum.
23 eastern slopes of Ural Mountains, USSR (Jousé
1955).
24. Reported as Sceletonema spinosum.
24 eastern slopes of Ural Mountains, USSR (Jousé
1955).
25. Reported as Trochosira coronata.
25 ODP Hole 913B (Scherer and Koç 1996).
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 8
Legend on opposite page.
eight radial hyaline ridges from the edge between the mantle
and the valve face to the elevated central top. Radial hyaline
ridges with arranged knobs and short spines on it, and smaller
anastomosing hyaline ridges present between these ridges.
Mantle hyaline, perforated by small pores and small hyaline
anastomosing ribs. The pore which is present on the top of the
central raised platform (Fenner 1994) was not observed in this
study. Hypovalve is featureless, with a raised rim and concave
central area, occasionally with a slightly central elevation (see
figure 14 in Hargraves 1984), although frustule was not observed in this study.
Type level and locality: Lower Eocene, Mors Formation in
Jutland, Denmark (Grunow in Van Heurck 1880-1885).
Type specimen: Depository not designated.
Comparison: This species is very similar to Kentrodiscus
blandus Long, Fuge et Smith (1946) of Nikolaev et al. (2001, p.
25, pl. 36, figs. 1-5), which was found in late Cretaceous marine
deposits in the Marca Shale Member, California. Both species
have a cylindrical highly vaulted valve shape with a flat top possessing a slit in the central part. In Nikolaev et al. (2001), the
specimens are illustrated with a nearly flat hypovalve covered
with numerous short strong spines. The genus Kentrodiscus
Pantocsek (1903), which contains some species from the late
Cretaceous, for example, K. fossilis Pantocsek (1903), K.
aculeatus Hanna (1927b), K. andersoni Hanna (1927b) and K.
armatus Hajós in Hajós and Stradner (1975), is characterized by
having valves protracted to form a hollow tube with a flat top
with numerous strong spines on the epi- and hypovalve faces.
Kentrodiscus blandus lacks spines on the epivalve surface, but
has radially arranged hyaline ridges which run from the edge
275
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
between the mantle, therefore K. blandus may belong to the genus Porotheca although the hypovalve structure of Po. danica
is unknown.
This species is also similar to Pseudopyxilla carinifera in that
the valve shape forms a hollow tube with radially arranged
hyaline ridges running from the flat top to mantle edge, but it
differs from the latter by its larger valve size and the possession
of hyaline ridges with knobs and spines on it. Pterotheca
pokrovskajae Jousé sensu Harwood (1988, p. 86, figs. 12.9-10,
18.19-23) may be distinguished from Po. danica by the lack of
abundant pores on its valve.
Stratigraphic and geographic distributions: This species was
frequently found in late Cretaceous to early Miocene sediments
(Text-figure 3). This species was found in late Cretaceous and
early Paleocene sediments from Seymour Island, Antarctic
Peninsula (Harwood 1988), from late Cretaceous DSDP Site
275 sediments at the southeast margin of Campbell Plateau near
New Zealand (Hajós and Stradner 1975), and from the Alpha
Ridge, Arctic Ocean (Dell’Agnese and Sreelatha 1989). With
regards to Eocene sediments, this species has been reported
from all parts of the world including the IODP Expedition 302,
central Arctic Ocean, however it was also found in the Southern
Hemisphere in Oligocene sediments and from the high latitude
Pacific Ocean in early Miocene deposits.
Etymology: Not designated. – but presumably refers to Denmark.
Pseudopyxilla carinifera (Grunow in Van Heurck) Suto, Jordan et
Watanabe comb. nov.
Basionym: Pyxilla ? carinifera GRUNOW in VAN HEURCK
1880-1885, pl. 83, fig. 5, 6. – HOMANN 1991, p. 139, pl. 55, figs. 1-5,
nec figs. 6, 8.
Synonymy: Pterotheca carinifera (GRUNOW in VAN HEURCK)
FORTI 1909, p. 13. – DESIKACHARY and SREELATHA 1989, p.
218, pl. 142, fig. 10.
Pterotheca carinifera GRUNOW, HANNA 1927a, p. 119, pl. 20, figs.
9, 10. – PROSCHKINA-LAVRENKO 1949, p. 203, pl. 75, figs. 7a, b;
pl. 77, fig. 1; pl. 98, fig. 8. – SHESHUKOVA-PORETSKAYA 1967,
p. 270. – GOMBOS 1976, p. 596, pl. 23, figs. 1, 2.
Pyxilla (Rhizosolenia?) carinifera Grunow sensu CLEVE-EULER
1951, Handl. 2: 1, p. 93, fig. VI-p.
Pterotheca carinifera var. curvirostris JOUSÉ 1955, p. 99, pl. 2, fig. 7. –
HARWOOD 1988, p. 86, fig. 18.7.
Pterotheca carinifera GRUNOW in VAN HEURCK – MCCOLLUM
1975, p. 535, pl. 16, figs. 6, 7 nec pl. 10, fig. 4.
Pterotheca carinifera (Grunow) FORTI – SCHRADER and FENNER
1976, p. 994, pl. 9, fig. 6; pl. 43, fig. 12. – LEE 1993, p. 42, pl. 1, fig.
19; pl. 2, fig. 17 nec pl. 3, fig. 10. – FENNER 1994, p. 116.
Pterotheca minor HARWOOD 1988, p. 86, figs. 12.12, 13. – HARWOOD and BOHATY 2000, p. 93, pl. 3, figs. r, s.
Description: Epivalve convex, cylindrical with a high mantle,
diameter 7-22µm, transapical axis 10-70µm. The central part of
epivalve face protracted to form a hollow tube with a flat top.
Epivalve surface generally structured by four radial hyaline
ridges from the edge between the mantle and the valve face to
the elevated central top, hyaline between radial hyaline ridges.
Mantle distinct and hyaline. Hypovalve nearly flat and featureless (see pl. 55, figure 2 in Homann 1991), although frustule
was not observed in this study.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not given.
276
Comparison: This species is easily distinguished from Porotheca danica by its more slender valve and its possession of
hyaline ridges lacking knobs and spines. This species also resembles Pterotheca spada (= Pt. subulata) and Pseudopyxilla
capreolus in possessing a hollow tube on its epivalve, but is
identified from the former by its nearly flat hypovalve and from
the latter by lacking a dichotomous branching hyaline process at
the distal end of the hollow tube.
Stratigraphic and geographic distributions: This species occurs
from the late Cretaceous to the late Miocene (Text-figure 3).
This species was not observed in this study.
Remarks: This species is characterized by its hyaline cylindrical
to conical valve, therefore this species was transferred to the genus Pseudopyxilla in this study. When Fenner (1994) erected
the genus Porotheca, she mentioned that it is characterized by
cylindrical to conical valves with a central elevation with a
pore-like opening on top. It is unknown whether or not Ps.
carinifera possesses such a pore-like opening, however its
stratigraphic and geographic distributions resemble closely
those of Po. danica, therefore Ps. carinifera may belong to the
genus Porotheca and be a variety of Po. danica.
The specimens of Pterotheca carinifera in Harwood (1988, p.
86, fig. 18.6), Harwood and Bohaty (2000, p. 93, pl. 3, fig. t; pl.
9, fig. o) and McCollum (1975, p. 535, pl. 16, figs. 6, 7 nec pl.
10, fig. 4), and of Pyxilla? carinifera in Homann (1991, p. 139,
pl. 55, figs. 6, 8 nec figs. 1-5) are identified as Porotheca danica
because their large valves with hyaline ridges are covered with
knobs and spines. The specimen of Pterotheca carinifera in Lee
(1993, p. 42, pl. 3, fig. 10 nec pl. 1, fig. 19; pl. 2, fig. 17) is
Pterotheca subulata.
Etymology: The Latin carinifera means “coarse keel”.
Pseudopyxilla dubia (Grunow in Van Heurck) Forti 1909
Plate 8, figures 1-21
Pseudopyxilla dubia (Grunow) FORTI 1909, pl. 1, figs. 1-3. – HAJÓS
1968, p. 136, pl. 38, figs. 2, 3. – HANNA 1970, p. 191, figs. 66, 68. –
SCHRADER and FENNER 1976, pl. 44, figs. 13, 14. – FENNER
1978, p. 526, pl. 14, fig. 9; pl. 17, figs. 1-6. – GOMBOS and
CIESIELSKI 1983, p. 603. – GOMBOS 1984, p. 500, pl. 2, figs.
10-12. – FENNER 1994, p. 115, pl. 9, fig. 12. – HARWOOD and
BOHATY 2000, pl. 4, fig. d.
Pseudopyxilla dubia Grunow – PROSCHKINA-LAVRENKO 1949, p.
200, pl. 73, fig. 13; pl. 98, figs. 1a, b.
Pseudopyxilla dubia (Grunow in Van heurck) FORTI – BARRON
1975, p. 152, pl. 11, fig. 13. – HARWOOD 1988, p. 85, figs. 17.23, 24.
Basionym: Pyxilla? dubia Grunow in VAN HEURCK 1880-1885, pl.
83, figs. 7, 8.
References: Pyxilla dubia Grunow in VAN HEURCK 1880-1885, pl.
83, fig. 12. – HASEGAWA 1977, p. 87, pl. 21, fig. 4. – DESIKACHARY and SREELATHA 1989, p. 219, pl. 93, figs. 3-6, 15.
Pyxilla dubia Grunow – HANNA 1927a, p. 119, pl. 20, fig. 13.
Pyxilla (Rhizosolenia?) dubia Grunow in CLEVE-EULER 1951, Handl.
2: 1, p. 93, figs. VI-n.
Pyxilla (Pyxilla) dubia Grunow ex VAN HEURCK sensu KANAYA
1957, p. 114, pl. 8, fig. 10.
Rhizosolenia dubia (Grunow) HOMANN 1991, p. 69, figs. 1-8, 11-13.
Synonymy: Rhizosolenia americana Ehrenberg sensu EHRENBERG
1854, pl. 18, figs. 98a, h, i nec figs. 98b-g.
Pseudopyxilla americana (Ehrenberg) FORTI sensu HAJÓS and
STRADNER 1975, p. 933, pl. 12, fig. 3.
Pyxilla ? baltica Grunow in VAN HEURCK 1880-1885, pl. 83, figs. 1,
2.
Pyxilla baltica Grunow in VAN HEURCK 1880-1885, pl. 83 bis., fig. 4.
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 9
Generalized biostratigraphic ranges of diatom resting spore morpho-species from the early to middle Eocene cores in the central Arctic Ocean and their
allied species. Black and gray lines mean the occurrences from sediments in the Northern and Southern Hemispheres, respectively. Star symbols mean
that the specimens may be vegetative cells. Species enclosed with squares were not observed in the IODP Expedition 302 samples. The biostratigraphic
data of genera Goniothecium and Odontotropis are modified after Suto et al. (2008 and submitted).
Pseudopyxilla baltica (Grunow) FORTI 1909, pl. 1, figs. 8, 9. –
PROSCHKINA-LAVRENKO 1949, p. 201, pl. 98, figs. 6a-c. –
SCHRADER and FENNER 1976, p. 994, pl. 44, figs. 3, 6, 9.
Pseudopyxilla baltica (?)(Grunow) FORTI – HARWOOD and
MARUYAMA 1992, p. 705, pl. 2, figs. 9, 10.
Pyxilla russica PANTOCSEK 1905, Bd. 3, pl. 19, fig. 277. –
DESIKACHARY and SREELATHA 1989, p. 220, pl. 93, fig. 12.
Pseudopyxilla russica (Pantocsek) Forti sensu HANNA 1927b, p. 27,
pl. 4, fig. 4. – PROSCHKINA-LAVRENKO 1949, p. 200, pl. 97, fig.
7; pl. 75, fig. 3. – HAJÓS and STRADNER 1975, p. 933, pl. 12, figs.
1, 2; pl. 27, fig. 9. – FENNER 1994, p. 115. – NIKOLAEV et al. 2001,
p. 24, pl. 35, figs. 1, 2.
Pseudopyxilla rossica (Pantocsek) FORTI 1909, p. 14, pl. 1, fig. 13. –
SHESHUKOVA-PORETSKAYA 1967, p. 261, pl. 39, figs. 1a, b. –
STRELNIKOVA 1974, p. 111, pl. 56, figs. 6-8. – SCHRADER and
FENNER 1976, p. 994, pl. 12, figs. 19, 20; pl. 44, figs. 2, 4, nec pl. 44,
fig. 5. – HARWOOD 1988, p. 86, figs. 17.28, 29. – HOMANN 1991,
p. 134, pl. 54, fig. 12.
Pseudopyxilla rossica (?) – SCHRADER and FENNER 1976, p. 994, pl.
12, figs. 19, 20; pl. 44, figs. 2, 4 nec pl. 44, fig. 5.
Pyxilla hungarica PANTOCSEK 1905, Bd. 3, pl. 26, fig. 392.
Pseudopyxilla hungarica (Pantocsek) FORTI 1909, p. 14. – HARWOOD 1988, p. 85, figs. 17.26, 27.
Pyxilla vasta PANTOCSEK 1905, Bd. 3, pl. 40, fig. 551.
Pseudopyxilla tempereana FORTI 1909, p. 15, pl. 1, fig. 11. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 98, fig. 2. – GLEZER
et al. 1974, pl. 53, fig. 11. – FENNER 1991. p. 139, pl. 9, fig. 3. –
FENNER 1994, p. 115.
Pseudopyxilla peragallorum FORTI 1909, p. 16, pl. 1, fig. 10. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 97, fig. 6.
Pseudopyxilla obliquepileata FORTI 1909, p. 17, pl. 1, fig. 12. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 98, figs. 3a-b.
Pyxilla (Rhizosolenia?) antiqua CLEVE-EULER 1951, Handl. 2: 1, p.
93, figs. 167, VI-o.
Pseudopyxilla sp. of FENNER 1978, p. 526, pl. 17, fig. 7. – FENNER
1991, p. 139, pl. 9, fig. 4. – NIKOLAEV et al. 2001, p. 24, pl. 35, fig. 3.
277
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Rhizosolenia setigera Brightwell sensu HOMANN 1991, p. 71, pl. 35,
figs. 9, 10.
Description: Frustule heterovalvate. In valve view, valve circular, convex in the middle. Valve surface hyaline or covered with
numerous dense and minute puncta. In girdle view, valve convex, cylindrical with a high mantle, 5-70µm in diameter. Height
of valve is variable, nearly 1 to 7 times its diameter. Mantle distinct and all surface hyaline or hyaline near the top or bottom of
mantle with numerous puncta on lower area. Opposite valve
circular, convex in the middle, sometimes preserved with a delicate crown which are covered with dense and minute puncta.
Valve surface hyaline or covered with numerous dense and
minute puncta. In girdle view, valve convex, cylindrical with a
high mantle. Height of valve is variable, nearly 1 to 7 times its
diameter. Mantle distinct, entire surface hyaline or hyaline near
the top or bottom of mantle with numerous puncta on lower
area. It is unknown which of the valves is the epivalve or
hypovalve in this study.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not designated.
Comparison: This species is very similar to other Pseudopyxilla species like Ps. aculeata and Ps. directa in having cylindrical and conical valves, and Ps. americana, Ps. capreolus and
Ps. jouseae in having cylindrical valves, but is differentiated
from the former two species by its lower convex valve, and
from the latter three species by the absence of a branching process on the valve top.
Stratigraphic and geographic distributions: This species is cosmopolitan and a long-ranged species from the late Cretaceous
through to the Pliocene (Text-figure 4).
Remarks: Several species which possess highly cylindrical and
convex valves that are hyaline or covered with numerous dense
puncta have been described as Ps. baltica, Ps. dubia, Ps.
hungarica, Ps. obliquepileata, Ps. peragallorum, Ps. russica
(sometimes misspelled rossica) and Ps. tempereana. These species may be separated by the presence or absence of puncta on
the valve mantle and by differences in the height of the holotype
specimens. Another confusion may have been caused by the difficulty in identifying specimens which are preserved in the sediments as separated valves (such as only one valve or an opposite
valve with/without a crown). However several forms with/without puncta were observed in middle Eocene IODP Leg 302 samples (at one site) and most of the stratigraphic and geographic
distributions of these species are cosmopolitan and long-ranged
indicating little differences between them (Text-figure 4).
Therefore we assumed that these species belong to a single or
are varieties of one species.
According to Homann (1991), the resting spore type “Pseudopyxilla” belongs to species related to the genus Rhizosolenia,
because Homann (1991) found that the vegetative cells look like
Rhizosolenia and are very different from resting spores. Thus
most relationships between these different frustule types remain
unknown. Therefore the resting spore morpho-genus Pseudopyxilla is here maintained. The Rhizosolenia-like vegetative
valves are also illustrated in Proschkina-Lavrenko (1949).
Moreover, Marino et al. (1991) also hypothesized that the fossil
species Pyxilla dubia has a closer affinity to the genus
Chaetoceros than to the genus Rhizosolenia based on the origi-
PLATE 1
Anaulus arcticus sp. nov.
All figures are transmitted light micrographs (LM). Scale bar = 10µm, which applies to all figures.
1,2 Holotype. IODP Site 302-2A-61X-2, 2-3cm. Girdle
view of paired valves.
18,19 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
3,4 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
paired valves.
20,21 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
5,6 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
paired valves.
22,23 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
7,8 IODP Site 302-2A-55X-CC. Girdle view of paired
valves.
24,25 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
9,10 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
paired valves.
26,27 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
11,12
IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
paired valves.
28,29 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
frustule.
13-15 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
30,31 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule connected to hypovalve of opposite valve.
16,17 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
paired valves.
278
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 1
279
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
nal drawing of Forti (1909). Sometimes valves are preserved
with a delicate crown covered with dense puncta (see Van
Heurck 1880-1885, Desikachary and Sreelatha 1989). From
their illustrations, the crown on some spore valves may represent preserved vegetative cells.
Etymology: The Latin dubia means “uncertain”.
Pseudopyxilla jouseae Hajós in Hajós and Stradner 1975
Plate 8, figures 22-31
Pseudopyxilla jouseae HAJÓS in HAJÓS and STRADNER 1975, p.
933, pl. 12, figs. 4, 5.
Synonym: Pterotheca sp. (aff. carinifera Grunow) of JOUSÉ 1951, p.
59, pl. 4, fig. 4.
Emended description: Frustule heterovalvate. In valve view,
valve circular. Valve surface hyaline, covered with numerous
wrinkles and nearly straight ridges from the top of the conical
area to the mantle margin. In girdle view, valve 5-20µm in di-
ameter, cylindrical with a high mantle, conical at one end, and
extending into a long tapered spine. The tapered spine bifurcated at the end (see pl. 8, fig. 30). Height of valve is variable,
nearly 1 to 4 times its diameter not including the conical area
with long tapered spine. Mantle distinct, covered with numerous wrinkles. Opposite valve (perhaps hypovalve) circular, convex (see pl. 8, figs. 26, 27).
Type level and locality: Upper Cretaceous. DSDP Site 275 (lat.
50° 26.34’ S, 176° 18.99’ E) in 2,837 m water depth on the eastern edge of the Campbell Plateau to the southwest of the Bounty
Islands, South Pacific; in sample 1-1, 118-120cm.
Type specimen: Deposited in the collections of the Hungarian
Geological Survey, Budapest; holotype (figs. 4, 5), no. 2799/1.
Comparison: This species is characterized by a conical and cylindrical valve covered with wrinkles, and a long tapered and bifurcating spine.
PLATE 2
Anaulus arcticus sp. nov.
Figures 1-35 are LM and figs. 36-47 are SEM, respectively. The scale bar in fig. 1 is 10µm and it also applies to figs. 2-35.
The scale bars in figs. 36-47 are 10µm.
1 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
2,3 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
4-6 IODP Site 302-2A-59X-CC, 0-1cm. Frustule in valve
view.
7,8 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
9,10 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
11,12 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
13,14 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
15,16 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
17,18 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
19,20 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
37 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
38 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
39 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve.
40 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve.
41 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve
42 IODP Site 302-4A-5X-1, 2-3cm. Oblique valve view
of hypovalve.
43 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
21,22 IODP Site 302-4A-6X-2, 2-3cm. Valve view.
23,24 IODP Site 302-4A-7X-1, 2-3cm. Valve view.
25-27 IODP Site 302-4A-5X-1, 2-3cm. Valve view.
28,29 IODP Site 302-4A-5X-1, 2-3cm. Valve view.
30,31 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
32,33 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
34,35 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
36 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
280
44 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
hypovalve.
45 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
hypovalve.
46 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
paired valves.
47 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view
of frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 2
281
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Stratigraphic and geographic distributions: Hajós and Stradner
(1975) reported this species from the late Cretaceous cores of
DSDP Site 275 and this species was observed in middle Eocene
cores of IODP Leg 302 in this study (Text-figure 4).
Etymology: This species was named in honor of Dr. A. P. Jousé.
Pterotheca aculeifera Grunow in Van Heurck 1880-1885 (= Pterotheca crucifera Hanna 1927b)
Plate 9, figures 1-47
Basionym: Pterotheca (Pyxilla ??) aculeifera GRUNOW in VAN
HEURCK 1880-1885, pl. 83 bis, fig. 5.
References: Pterotheca aculeifera GRUNOW, VAN HEURCK 1896,
p. 430, fig. 151. |PROSCHKINA-LAVRENKO 1949, p. 202, pl. 75,
fig. 4b nec fig. 4a. – SHESHUKOVA-PORETSKAYA 1967, p. 266. –
GLEZER et al. 1974, pl. 12, fig. 5. – STRELNIKOVA 1974, p. 114,
pl. 57, figs. 1-16, 23-26 nec figs. 17-22 – GOMBOS 1977, p. 596, pl.
23, figs. 1, 2. – SCHRADER and FENNER 1976, p. 994, pl. 43, figs.
1-4. – FENNER 1978, p. 527, pl. 17, figs. 8-21. – DZINORIDZE et al.
1978, pl. 9, fig. 6. – GOMBOS 1983, p. 570. – GOMBOS and
CIESIELSKI 1983, p. 603. – GOMBOS 1984, p. 500. – SANFILIPPO
and FOURTANIER 2003, pl. 3, fig. 7. – TSOY 2003, pl. 1, fig. 7.
Pterotheca aculeifera Grunow in VAN HEURCK 1896, p. 430, fig. 151.
– HAJÓS 1976, p. 829, pl. 16, figs. 6-8. – SCHERER and KOÇ 1996,
p. 86, pl. 8, fig. 11. – TAPIA and HARWOOD 2002, p. 328.
Pterotheca aculeifera (Grunow) VAN HEURCK – BALDAUF 1985, p.
464, pl. 10, figs. 13, 14. – FENNER 1994, p. 116, pl. 4, fig. 8.
Pterotheca aculeifera (Grunow in VAN HEURCK) VAN HEURCK –
HARWOOD 1988, p. 86, figs. 18.3, 4. – DESIKACHARY and
SREELATHA 1989, p. 218, pl. 93, fig. 11.
Pterotheca aculeifera (Grunow) GRUNOW em. HOMANN 1991, p.
135, pl. 35, figs. 15-18. – HARWOOD and BOHATY 2000, p. 93, pl.
1, fig. l; pl. 9, fig. p.
PLATE 3
Figures 1-22, 24-36, 38, 39, 41-52 are LM and figs. 23, 37, 40 and 53 are SEM, respectively.
The scale bars in figs. 1 and 2, and 24 and 25 are 10µm and those also apply to figs. 3-22 and 41-52, and 26-33, respectively.
The scale bars in figs. 23, 37, 38 and 39, 40 and 53 are 10µm, respectively.
1-23. Resting spore sp. C.
1,2 IODP Site 302-2A-54X-CC. Girdle view of frustule.
3,4 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
5,6 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
7,8 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
9,10 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
11,12 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
13,14 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
15,16 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
17,18 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
19,20 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
21,22 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
23 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
24-37. Costopyxis trochlea (Hanna) Strelnikova in Glezer et al.
24,25 DSDP Leg 38, Site 338-29-1, 130-131cm. Girdle
view of frustule.
26,27 DSDP Leg 38, Site 338-29-1, 130-131cm. Girdle
view.
282
28 DSDP Leg 38, Site 338-29-1, 130-131cm. Valve
view.
29,30 IODP Site 302-2A-54X-CC. Girdle view.
31-33 IODP Site 302-2A-61X-2, 2-3cm. Girdle view.
34-36 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
37 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
38-40. Liradiscus ? sp. A.
38,39 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
40 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
41-53. Peripteropsis ? sp. A.
41,42 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
43,44 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
45,46 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
47,48 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
49,50 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
51,52 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
53 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view
of frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 3
283
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
2A and 4A of IODP Expedition 302 (Moran et al. 2006). In the
lower part of Unit 2, resting spores occurred abundantly with
other fossil diatoms.
In this paper, we have attempted to provide taxonomic notes on
the fossil resting spore taxa from middle Eocene Arctic core
materials, with a synonymy list, microscope observations and
several key references for each taxon. Our main goal is to identify the main diatoms and resting spore assemblages in order to
apply diatom biostratigraphy to the stratigraphic sequence of
the material from the central Arctic Ocean. The detailed stratigraphic data and paleoceanographic and paleoecological implications of the Eocene Arctic Ocean were presented by Stickley
et al. (2008) for Holes 2A and 4A. However, the taxonomy of
some of the other diatoms except for resting spore taxa from the
ACEX cores will be described in subsequent papers.
MATERIAL AND METHODS
IODP Expedition 302 (or ACEX), recently obtained Recent to
Cretaceous marine sedimentary records from Holes 2A and 4A
(~87°52.00’N; 136°10.64’E; 1288m water depth; Text-figure
1), on the Lomonosov Ridge in the central Arctic Ocean.
Biostratigraphy and magnetostratigraphy were used to construct an age model, with dinocysts providing the bulk of the
Neogene biostratigraphic data, and diatom, ebridian and
silicoflagellate data being used to date the Eocene (Backman et
al. 2005a).
The expanded late early to middle Eocene sediment sequences
of Holes 302-2A and 302-4A typically comprise abundant fossils of dinoflagellate and chrysophyte cysts, diatoms, ebridians,
and silicoflagellates. Biosilica is not present before the late
early Eocene interval (~320m) and above the interval (205m~).
In these Eocene sediments, a lot of fossil resting spore valves
were preserved with other diatom frustules.
In this study, samples of a nearly complete section of Tertiary
sediments of DSDP Leg 38 Site 338 (67° 47.11’ N, 05° 23.26’
E; water depth 400.8m; Text-figure 1) are also used to compare
some resting spore taxa in the Norwegian Sea with those in the
Arctic Ocean. These samples contain well-preserved diatoms of
middle Eocene, Oligocene and early to middle Miocene.
Processed strewn slides were prepared following the method of
Suto (2003). Diatom frustules were mounted in pleurax for LM
observations and coated with gold for SEM observation. Identification and photodocumentation of resting spores were made
at x400 using an Olympus BM40 light microscope and Olympus DP-12 digital camera. SEM examinations were carried out
using a JEOL JSM-5800 LV scanning electron microscope at
the National Science Museum of Japan.
RESULTS
Anaulus arcticus Suto, Jordan et Watanabe sp. nov.
Plate 1, figures 1-31; Plate 2, figures 1-47
Synonymy: Anaulus sibiricus STRELNIKOVA sensu BARRON 1985,
p. 141, pl. 10.2, fig. 10. – HARWOOD 1988, p. 79, figs. 9.12-14. –
DELL’AGNESE and CLARK 1994, fig. 3.3.
Anaulus sp. A in HARWOOD 1988, p. 79, figs. 9.16, 17.
Anaulus sp. in BARRON and MAHOOD 1993, p. 38, pl. 4, fig. 7.
Description: Frustule heterovalvate. Valve broadly linear with
large, cuneate, bluntly rounded apices, apical axis 10-35µm,
transapical axis 6-14µm. Valve divided into 3 or 5 equal parts
by 2 or 4 transverse internal septa. Epivalve rectangular,
260
vaulted with 3 or 5 slightly inflated undulations in girdle view.
Epivalve surface covered with randomly scattered fine pores.
Each end is slightly raised with one strong short curved spine.
One rimoportula near the center of the epivalve. Mantle of
epivalve distinct with rows of dense pores. Hypovalve rectangular with marginal ridge in girdle view. There are two types of
marginal ridge, one at the absolute margin between hypovalve
and mantle, the others close to the inner part of the margin. Internal marginal ridge area flat or slightly undulated. No
rimoportula on the hypovalve. Mantle of hypovalve distinct
with fine pores near the valve area, hyaline around opposite
part. Paired valves formed by two types of hypovalves completely connected by marginal ridges.
Type level and locality: Middle Eocene, IODP Expedition
302-4A, 11X-CC, Arctic Ocean.
Holotype here designated: Slide MPC-04958 (Micropaleontology Collection, National Science Museum, Tokyo,
England Finder N31-4; illustrated in Plate 1, Figs. 1, 2).
Comparison: It is difficult to distinguish our new species from
A. mediterraneus var. mediterraneus Grunow in Van Heurck
(1880-1885) and A. americanus Hustedt (1955), however, A
arcticus has random scattered pores on its epivalve. This species differs from A. mediterraneus var. intermedia Grunow in
Van Heurck (1880-1885) by its round apex, and from A.
minutus Grunow in Van Heurck (1880-1885) and A. sibiricus
Strelnikova (1974) by its rounded valve in girdle view.
Stratigraphic and geographic distributions: This species occurred abundantly in middle Eocene sediments from IODP Leg
302 Sites 2A and 4A in the central Arctic Ocean (Text-figure 2).
Barron (1985) and Dell’Agnese and Clark (1994) also reported
this species as A. sibiricus from the late Cretaceous Alpha
Ridge, Arctic Ocean. On the other hand, Harwood (1988) and
Barron and Mahood (1993) also reported this species as A.
sibiricus and A. sp A. from the early Paleocene to the late Cretaceous Antarctic Ocean, and as A. sp. from the early Oligocene
Antarctic Ocean, respectively. According to Hustedt (1930) and
Abbott and Andrews (1979), the similar species A. mediterraneus was a littoral form inhabiting warm waters, such as the
south coast of England and the Mediterranean, therefore our
new species may have lived in warm and littoral environments.
Remarks: Harwood (1988) mentioned that the occurrence of A
arcticus (= their specimens of A. sibiricus) and Hemiaulus
elegans in resting spore and vegetative cell diatom assemblages,
respectively, from the Arctic Ocean (Kitchell et al. 1986), and
suggests that A. arcticus is a resting spore of H. elegans.
Anaulus mediterraneus var. intermedia Grunow in Van Heurck
(1880-1885, pl. 102, fig. 9) and in Wornardt (1967, p. 68, fig.
134) is characterized by its constricted valve center and tapered
valve apex, but this variety illustrated in Hustedt (1930, p. 892,
fig. 535), Proschkina-Lavrenko (1949, p. 212, pl. 99, fig. 13)
and Abbott and Andrews (1979, p. 233, pl. 1, fig. 14) may be a
new variety of this species because their valves are not constricted and have a slightly lanceolated apex. Hustedt (1955) indicated that A. americanus differs from A. mediterraneus by its
smaller size and finer structure but A. americanus might be only
a variety of A. mediterraneus.
Etymology: The Latin word arcticus means “Arctic”.
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 1
Location map of Integrated Ocean Drilling Program (IODP) Expedition (or the Arctic Coring Expedition, ACEX) Leg 302 in the Arctic Ocean.
Costopyxis trochlea (Hanna) Strelnikova in Glezer et al. 1988
Plate 3, figures 24-37
Costopyxis trochlea (Hanna) STRELNIKOVA in GLEZER et al. 1988,
p. 51, pl. 32, figs. 17, 18. – SCHERER and KOÇ 1996, p. 86, pl. 8, figs.
8-10. – GLADENKOV 1998, pl. 1, figs. 11a, b. – TSOY 2003, pl. 2,
fig. 12.
Basionym: Trochosira trochlea HANNA 1927a, p. 123, pl. 21, figs. 8, 9.
Synonymy: Pterotheca sp. (1) of SCHRADER and FENNER 1976, p.
994, pl. 35, fig. 15.
Pterotheca sp. (3) of SCHRADER and FENNER 1976, p. 994, pl. 35,
figs. 17, 18.
Pterotheca sp. (4) of SCHRADER and FENNER 1976, p. 994, pl. 35,
fig. 19.
Trochosira trochlea HANNA sensu DZINORIDZE et al. 1978, pl. 4,
figs. 12, 13. – FENNER 1985, p. 741, fig. 12.10. – FENNER 1991, pl.
11, fig. 15.
Pterotheca gracillima FENNER 1978, p. 527, pl. 12, figs. 5, 6. –
BARRON et al. 1984, p. 156, pl. 8, fig. 11.
Pterotheca sp. of FENNER 1978, p. 527, pl. 12, fig. 3.
Pterotheca sp. 4 of FENNER 1978, p. 527, pl. 12, fig. 4.
Pterotheca sp. of BARRON et al. 1984, p. 156, pl. 8, fig. 12.
Trochosira aff. gracillima (Fenner) FENNER 1991, p. 141, pl. 11, figs.
22, 25.
Stephanopyxis ornata SCHULZ sensu HARWOOD and MARUYAMA
1992, p. 706, pl. 2, fig. 6.
Trochosira gracillima (Fenner) Fenner. – FENNER 1994, p. 122.
261
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Genus et species indet. C of HARWOOD and BOHATY 2000, p. 94, pl.
5, fig. p.
base of the mantle there is a ring of relatively large pedal “segments” (Fenner 1985).
Description: Frustule isovalvate, 4-8µm in diameter, pervalvar
axis 6-13µm without spine. Valves circular in valve view,
highly cylindrical with a convex upper part in girdle view. One
or sometimes two (Plate 3, figures 29, 30) long bifurcate spines
on top of the center. Valve face covered with very finely
punctate (20-22 puncta in 10µm) which are of constantly equal
size on the whole valve and are arranged in straight radial double- to triple-rows. A ring of short hyaline ridges at the transition between convex and cylindrical mantle of the valve. At the
Type level and locality: Lower Miocene, locality 894, Phoenix
Canyon, 7 miles north of Coalinga, Fresno County, California
(basionym species Trochosira trochlea Hanna 1927a). Middle
Eocene, planktonic foraminiferal zone P10/P11 (synonym species Pterotheca gracillima Fenner 1978).
Type specimen: Sample no. 3050, deposited in the Museum of
California Academy of Sciences (basionym species Trochosira
trochlea Hanna 1927a). Deposited in the sample collections of
TEXT-FIGURE 2 (opposite page)
Geographic and stratigraphic distribution of Anaulus arcticus Suto, Jordan et Watanabe,
Costopyxis trochlea (Hanna) Strelnikova in Glezer et al., Leptoscaphos punctatus (Grove et Sturt) Schrader and
Leptoscaphos levigatus (Sheshukova-Poretskaya) Suto, Jordan et Watanabe.
a-f. Anaulus arcticus
a IODP Site 302-2A and 4A (This study).
b-d. Reported as Anaulus sibiricus.
b Alpha Ridge, Arctic Ocean (Barron 1985);
c Seymour Island, Antarctic Peninsula (Harwood
1988);
d Alpha Ridge, Arctic Ocean (Dell’Agnese and Clark
1994).
e, f. Reported as Anaulus sp.
e Seymour Island, Antarctic Peninsula (Harwood
1988);
f ODP Hole 739C (Barron and Mahood 1993).
1-20. Costopyxis trochlea
1-4. Reported as Costopyxis trochlea.
1 Kamchatka, Russia (Glezer et al. 1988);
2 ODP Hole 913B (Scherer and Koç 1996);
3 Kamenka Formation, Bering Island (Gladenkov
1998);
4 IODP Site 302-2A and 4A (This study).
5-9. Reported as Trochosira trochlea.
5 the lower Miocene shales, north of Coalinga, California (Hanna 1927a);
6 DSDP Site 338 (Dzinoridze et al. 1978);
7 DSDP Site 340 (Dzinoridze et al. 1978);
8 Kellogg Shale, California (Fenner 1985);
9 DSDP Site 208 (Fenner 1991).
10-14. Reported as Pterotheca gracillima or Trochosira
gracillima.
10 DSDP Site 356 (Fenner 1978);
11 DSDP Site 338 (Fenner 1978);
12 Kellogg Shale, California (Barron et al. 1984);
13 DSDP Hole 700B (Fenner 1991);
14 Fur Formation, Denmark (Fenner 1994).
15-17. Reported as Pterotheca sp.
15 DSDP Site 338 (Schrader and Fenner 1976);
16 DSDP Site 356 (Fenner 1978);
17 Kellogg Shale, California (Barron et al. 1984).
18, 19. Reported as Stephanopyxis ornata.
18 ODP Hole 748B (Harwood and Maruyama 1992);
19 ODP Hole 749B (Harwood and Maruyama 1992).
20. Reported as Genus et species indet. C.
20 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
A-C. Leptoscaphos levigatus
A Rekinnik Inlet, eastern side of Penzhina Bay,
Kamchatka, Russia (Sheshukova-Poretskaya 1967);
B Anadyr River, Russia (Sheshukova-Poretskaya
1967);
C IODP Site 302-2A and 4A (This study).
D-F. Leptoscaphos punctatus
D Oamaru, New Zealand (Schrader 1969);
E Oamaru, New Zealand (Desikachary and Sreelatha
1989);
F IODP Site 302-2A and 4A (This study).
262
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 2
Legend on opposite page.
DSDP samples of Dr. H.-J. Schrader, School of Oceanography,
Oregon State University, Corvallis, Oregon (synonym species
Pterotheca gracillima Fenner 1978).
Comparison: The only similar form observed in the literature is
the upper Cretaceous Costopyxis schulzii (Steinecke) Glezer,
but this species is distinguished from C. trochlea by its much
larger size and coarser areolation with many small scattered
spines on the valve surface besides the two subcentral long
spines.
Stratigraphic and geographic distributions: The oldest occurrence of this species is from the early to late Paleocene sedi-
ments of ODP Hole 700B in the southwest Atlantic (Fenner
1991). This species mainly occurred from the early Eocene to
late Oligocene sediments all around the world (Text-figure 2).
Fenner (1978) described the species Pterotheca gracillima (p.
527, pl. 12, figs. 5, 6 in Fenner 1978) from the middle to late
Eocene cores of DSDP Site 356 at the southwestern edge of the
Sao Paulo Plateau, western South Atlantic. The youngest specimens are reported from early Miocene sediments in California
(Hanna 1927a).
Remarks: This species was formerly observed and named as
Pterotheca gracillima (e.g. Fenner 1978, Barron et al. 1984)
and Pt. sp. 1, 3 and 4 (Schrader and Fenner 1976), Stephano-
263
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
TEXT-FIGURE 3
(opposite page)
Geographic and stratigraphic distribution of Porotheca danica Grunow in Van Heurck and
Pseudopyxilla carinifera (Grunow in Van Heurck) Suto, Jordan et Watanabe.
1-28. Porotheca danica
1-2. Reported as Porotheca danica.
1 Fur Formation, Denmark (Fenner 1994);
2 IODP Site 302-2A and 4A (This study).
3-16. Reported as Pterotheca danica.
3 Mors Formation, Denmark (Van Heurck 1880-1881);
22. Reported as Stephanogonia novazealandica.
22 Oamaru, New Zealand (Desikachary and Sreelatha
1989).
23. Reported as Pterotheca cf. aculeifera.
23 DSDP Site 275 (Hajós and Stradner 1975).
24-26. Reported as Pterotheca carinifera.
24 DSDP Site 274 (McCollum 1975);
4 the early Miocene shales north of Coalinga, Fresno
County, California (Hanna 1927);
25 Seymour Island, Antarctic Peninsula (Harwood
1988);
5 DSDP Site 275 (Hajós and Stradner 1975);
26 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
6 DSDP Holes 280A, 281A and 283 (Hajós 1976);
7 DSDP Site 328 (Gombos 1977);
8 DSDP Hole 512 (Gombos 1983);
9 DSDP Site 511 (Gombos and Ciesielski 1983);
10 Kellogg Shale, northern California (Barron et al.
1984);
11 DSDP Hole 552A and Site 553 (Baldauf 1985);
12 Seymour Island, Antarctic Peninsula (Harwood
1988);
27. Reported as Pyxilla? carinifera.
27 Fur Formations, Denmark (Homann 1991).
28. Reported as Pterotheca spada.
28 DSDP Site 511 (Gombos and Ciesielski 1983).
a-l. Pseudopyxilla carinifera
a-f. Reported as Pterotheca carinifera.
a early Miocene shales north of Coalinga, California
(Hanna 1927a);
b DSDP Site 274 (McCollum 1975);
13 Oamaru, New Zealand (Desikachary and Sreelatha
1989);
c DSDP Site 338 (Schrader and Fenner 1976); d. DSDP
Site 348 (Schrader and Fenner 1976);
14 Yeonil Group in the Pohang Basin, Korea (Lee 1993);
e Oamaru, New Zealand (Desikachary and Sreelatha
1989);
15 Alpha Ridge, Arctic Ocean (Dell’Agnese and Clark
1994);
16 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
17-18. Reported as Pterotheca major.
17 eastern slope of Ural Mountains, USSR (Jousé 1955);
18 DSDP Hole 512 (Gombos 1983);
19 DSDP Site 511 (Gombos and Ciesielski 1983);
20 Seymour Island, Antarctic Peninsula (Harwood
1988).
21. Reported as Stephanogonia danica.
21 Fur Formations, Denmark (Homann 1991).
f Yeonil Group in the Pohang Basin, Korea (Lee 1993).
g, h. Reported as Pyxilla carinifera.
g Jutland, Denmark (Van Heurck 1880-1881);
h Fur and Mors Formations (Homann 1991).
i, j. Reported as Pterotheca carinifera var. curvirostris.
i eastern slope of Ural Mountains, USSR (Jousé 1955);
j Seymour Island, Antarctic Peninsula (Harwood
1988).
k, l. Reported as Pterotheca minor.
k Seymour Island, Antarctic Peninsula (Harwood
1988);
l McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
264
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 3
Legend on opposite page.
pyxis ornata (sensu Harwood and Maruyama 1992) and Genus
et species indet. C (Harwood and Bohaty 2000), but these taxa
all bear the same characteristics as C. trochlea. Specimens of
this species may not be resting spores, but actually vegetative
cells.
This species was described as a species of the genus Trochosira
by Hanna (1927a) because it possesses one long spine at the
valve center. Later, Trochosira trochlea was transferred to the
genus Costopyxis by Strelnikova in Glezer et al. (1988), because it has much coarser areolation with strong hyaline ridges
than other Trochosira species.
Etymology: The Latin costo-pyxis and trochlea means “box
with ribs” and “pulley”, respectively.
Dispinodiscus ? sp. A
Plate 4, figures 40-45
Description: Frustule heterovalvate, apical axis 8-10µm,
pervalvar axis 4-6µm without bristles. In girdle view, epivalve
hyaline, slightly vaulted with strong bristle near each apex and
its center, with distinct mantle. Mantle of epivalve hyaline.
Hypovalve vaulted in central area or nearly flat, with a strong
bristle at the center, with distinct mantle. Mantle of hypovalve
hyaline with a single ring of puncta at its base (see Plate 4, figure 40).
Comparison: This species is characterized by its hyaline epiand hypovalves with strong bristles at the valve center and near
each apex.
265
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
TEXT-FIGURE 4
Geographic and stratigraphic distribution of Pseudopyxilla dubia (Grunow in Van Heurck) Forti and
Pseudopyxilla jouseae Hajós in Hajós and Stradner.
1-44. Pseudopyxilla dubia
1-18. Reported as Pyxilla dubia and Pseudopyxilla dubia.
1 Jutland, Denmark (Van Heurck 1880-1881);
2 Deposit in Monterey, California (Van Heurck
1880-1881);
3 6 miles northwest of Newman, California (Hanna
1927a);
4 Mors Formation, Denmark (Cleve-Euler 1951);
5 Kellogg and “Sidney” shales, California (Kanaya
1957);
24 DSDP Site 338 (Schrader and Fenner 1976);
25 ODP Hole 747A (Harwood and Maruyama 1992).
26. Reported as Pseudopyxilla hungarica.
26 Seymour Island, Antarctic Peninsula (Harwood
1988).
27-37. Reported as Pyxilla russica (or P. rossica) and
Pseudopyxilla russica (or Ps. rossica).
27 Moreno Gulch, California (Hanna 1927b);
6 Szurdokpüspöki diatomite stop, Hungary (Hajós
1968);
28 North and South Sakhalin, Russia (SheshukovaPoretskaya 1967); 29. Western Siberia (Strelnikova
1974);
7 St. Paul Island, Bering Sea, Alaska (Hanna 1970);
30 DSDP Site 275 (Hajós and Stradner 1975);
8 Sisquoc Formation, California (Barron 1975);
31 DSDP Site 338 (Schrader and Fenner 1976);
9 DSDP Site 338 (Schrader and Fenner 1976);
32 DSDP Site 348 (Schrader and Fenner 1976);
10 Nakayama Formation, Sado Island, Japan (Hasegawa
1977);
33 Seymour Island, Antarctic Peninsula (Harwood
1988);
11 DSDP Site 356 (Fenner 1978);
12 DSDP Hole 511 (Gombos and Ciesielski 1983);
34 Oamaru, New Zealand (Desikachary and Sreelatha
1989);
13 DSDP Hole 524 (Gombos 1984);
35 Fur Formation, Denmark (Homann 1991);
14 Seymour Island, Antarctic Peninsula (Harwood
1988);
36 Fur Formation, Denmark (Fenner 1994);
37 Moreno Gulch, California (Nikolaev et al. 2001).
15 Oamaru, New Zealand (Desikachary and Sreelatha
1989);
38. Reported as Rhizosolenia setigera.
38 Mors Formation, Denmark (Homann 1991).
16 Fur Formation, Denmark (Fenner 1994);
39-41. Reported as Pseudopyxilla tempereana.
39 Western Siberia (Glezer et al. 1974);
17 McMurdo Sound, Antarctica (Harwood and Bohaty
2000);
18 IODP Site 302-2A and 4A (This study).
19. Reported as Rhizosolenia dubia.
19 Mors and Fur Formations, Denmark (Homann 1991).
20, 21. Reported as Rhizosolenia americana and Pseudopyxilla
americana.
20 Richmond, Virginia, USA (Ehrenberg 1854);
21 DSDP Site 275 (Hajós and Stradner 1975).
22. Reported as Pyxilla (Rhizosolenia?) antiqua.
22 Mors Formation, Denmark (Cleve-Euler 1951).
266
23-25. Reported as Pyxilla baltica and Pseudopyxilla baltica.
23 Mors Formation, Denmark (Van Heurck 1880-1881);
40 ODP Hole 700B (Fenner 1991);
41 Fur Formation, Denmark (Fenner 1994).
42-44. Reported as Pseudopyxilla sp.
42 DSDP Site 356 (Fenner 1978);
43 ODP Hole 700B (Fenner 1991);
44 Moreno Gulch, California (Nikolaev et al. 2001).
a, b. Pseudopyxilla jouseae
a DSDP Site 275 (Hajós and Stradner 1975);
b IODP Site 302-2A and 4A (This study).
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 4
Legend on opposite page.
Stratigraphic and geographic distributions: This species occurred rarely in middle Eocene sediments only from IODP Leg
302 Site 4A-6X-2, 2-3cm in the central Arctic Ocean.
Stratigraphic occurrence: This species was recognized abundantly in middle Eocene sediments from the Lomonosov Ridge,
Arctic Ocean in this study.
Remarks: This species may belong to the fossil resting spore
morpho-genus Dispinodiscus of extant Chaetoceros because of
the presence of a ring of puncta on the hypovalve margin. This
species looks like a Dispinodiscus species (see Suto 2004b), but
is distinguished from them by its central bristles on the epi- and
hypovalves.
Goniothecium decoratum Brun
Goniothecium danicum Grunow in Cleve et Möller emend. Suto in
Suto, Jordan et Watanabe 2008
Goniothecium rogersii Ehrenberg
Emended description: See Suto, Jordan and Watanabe (2008).
Emended description: See Suto, Jordan and Watanabe (2008).
Stratigraphic occurrence: This species was not observed in the
IODP Leg 302 samples.
Emended description: See Sims and Mahood (1998) and Suto,
Jordan and Watanabe (2008).
267
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Stratigraphic occurrence: This species was not observed in the
Arctic Coring Expedition sediments.
lowly truncated. Valve surface covered with numerous scattered fine puncta. Mantle distinct with scattered fine puncta.
Leptoscaphos levigatus (Sheshukova-Poretskaya) Suto, Jordan et
Watanabe comb. nov.
Type level and locality: the upper Middle Miocene to lower Upper Miocene, Etolon suite, Rekinnik Inlet, Kamchatka, Russia.
Plate 5, figures 1-28
Basionym: Biddulphia levigata SHESHUKOVA-PORETSKAYA
1967, p. 218, pl. 35, figs. 4a, b ; pl. 36, figs. 3a, b.
Type specimen: Deposited in the collection of the Chair of
Lower Plants, St.-Petersburg University, St.-Petersburg, Russia,
exhibit no. 1154.
Description: Frustule heterovalvate, apical axis 25-70µm,
pervalvar axis 7-10µm. Valve elongate, narrowly elliptical, or
narrowly lanceolate with rounded corners, sides subuniformly
curved. One valve slightly convex, the other nearly flat and
Comparison: This species resembles L. punctatus in valve
shape but is differentiated from the latter by its nearly hyaline
valve. Sheshukova-Poretskaya (1967) mentioned that this species is similar to spores of modern Antarctic neritic Biddulphia
TEXT-FIGURE 5 (opposite page)
Geographic and stratigraphic distribution of Pterotheca aculeifera (Grunow) Forti.
1-35. Pterotheca aculeifera
19 Fur Formation, Denmark (Fenner 1994);
1-27. Reported as Pterotheca aculeifera.
1 Jutland and Mors, Denmark (Van Heurck 18801881);
20 ODP Hole 913B (Scherer and Koç 1996);
2 Mors, Denmark (Van Heurck 1896);
3 Kellogg and “Sidney” shales, California (Kanaya
1957);
4 Lower course of the Anadyr River, Russia
(Sheshukova-Poretskaya 1967);
5 Western Siberia (Glezer et al. 1974);
6 Western Siberia (Strelnikova 1974);
7 DSDP Site 328 (Gombos 1977);
8 DSDP Site 283 (Hajós 1976);
9 DSDP Site 338 (Schrader and Fenner 1976);
21 McMurdo Sound, Antarctica (Harwood and Bohaty
2000);
22 Slidre Fjord Section, Canada (Tapia and Harwood
2002);
23 Horton River Section, Canada (Tapia and Harwood
2002)
24 ODP Hole 1128C (Sanfilippo and Fourtanier 2003);
25 Kronotskii Bay, east Kamchatka, Russia (Tsoy 2003);
26 DSDP Site 338 (This study);
27 IODP Site 302-2A and 4A (This study).
28-31. Reported as Pterotheca crucifera.
28 Moreno Gulch, California (Hanna 1927);
10 DSDP Site 356 (Fenner 1978);
29 DSDP Site 275 (Hajós and Stradner 1975);
11 DSDP Site 340 (Dzinoridze et al. 1978);
30 Seymour Island, Antarctic Peninsula (Harwood
1988);
12 DSDP Holes 512 and 512A (Gombos 1983);
31 Moreno Gulch, California (Nikolaev et al. 2001).
13 DSDP Site 511 (Gombos and Ciesielski 1983);
14 DSDP Site 524 (Gombos 1984);
15 DSDP Hole 553A (Baldauf 1985);
33 ODP Hole 700B (Fenner 1991);
16 Seymour Island, Antarctic Peninsula (Harwood
1988);
34 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
17 Oamaru, New Zealand (Desikachary and Sreelatha
1989);
35. Reported as Pseudopyxilla americana.
35 Alpha Ridge, Arctic Ocean (Dell’Agnese and Clark
1994).
18 Mors and Fur Formations, Denmark (Homann 1991);
268
32-34. Reported as Pterotheca sp.
32 DSDP Hole 327A and Site 328 (Gombos 1977);
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 5
Legend on opposite page.
striata Karsten, but differs from it by the asymmetry of the
frustule, narrower valves, and random distribution of the
areolae.
Stratigraphic and geographic distributions: SheshukovaPoretskaya (1967) observed this species from the lower course
of the Anadyr River, the late Eocene to Oligocene opoka silt
stones, and from Etolon suite Rekinnik Inlet, Kamchatka, Russia. According to the last Russian Stratigraphic Schemes for the
Cenozoic of Kamchatka and Sakhalin, the age of the Etolon
suite is the late middle Miocene to early late Miocene. This species was observed abundantly in middle Eocene sediments from
IODP Leg 302 Sites 2A and 4A in the central Arctic Ocean in
this study (Text-figure 2).
Remarks: Specimens of this species may be resting spores of L.
punctatus or a related species because of the similarities in
valve size and shape, and the possession of much less puncta on
the valve surface.
Etymology: The Latin word levigatus means “smooth”.
Leptoscaphos punctatus (Grove et Sturt) Schrader 1969
Plate 6, figures 1-33
Leptoscaphos punctatus (GROVE et STURT) SCHRADER 1969, p. 15,
pl. 9, figs. 4a-b. – DESIKACHARY and SREELATHA 1989, p. 110,
pl. 75, figs. 9, 10.
Basionym: Stoschia (?) punctata GROVE et STURT 1887, p. 145, pl.
14, fig. 52.
269
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Description: Chain-forming (Plate 6, Figs. 32, 33). Frustule
isovalvate, apical axis 25-52µm, pervalvar axis 5-13µm. Valve
elongate, narrowly elliptical, or narrowly lanceolate with
rounded corners, sides subuniformly curved. Valve surface
slightly convex, with numerous scattered coarse puncta, some
interrupted by widely transverse hyaline unequal interspaces irregularly arranged. Rimoportula near the edge of mantle on the
valve central area. Mantle distinct with scattered equally spaced
and clearly separated puncta.
Comparison: This species bears a close resemblance to L.
levigatus but differs from it by having a valve covered with
coarser puncta.
Stratigraphic and geographic distributions: Schrader (1969)
collected this species from the late Eocene Totara Limestone,
Oamaru, New Zealand. This species was observed abundantly
in middle Eocene sediments from IODP Leg 302 Sites 2A and
4A in the central Arctic Ocean in this study (Text-figure 2).
Type level and locality: Not designated.
Remarks: Specimens of this species may be vegetative cells of
L. levigatus.
Type specimen: Depository not designated.
Etymology: The Latin word punctatus means “punctate”.
TEXT-FIGURE 6
Geographic and stratigraphic distribution of Pterotheca evermanii Hanna, Pterotheca harrensis (Fenner) Suto, Jordan et Watanabe,
Pterotheca kittoniana Grunow in Van Heurck, Pt. kittoniana var. minuta Fenner, Pt. kittoniana var. kamtschatica Gaponov,
Pt. minuta (Fenner) Suto, Jordan et Watanabe and Pt. reticulata Sheshukova-Poretskaya.
1-9. Pterotheca evermanii
1 upper Moreno Shale, California (Hanna 1927);
2 Western Siberia (Glezer et al. 1974);
3 Western Siberia (Strelnikova 1974);
4 Seymour Island, Antarctic Peninsula (Harwood
1988);
5 ODP Hole 700B (Fenner 1991);
6 Mors and Fur Formations, Denmark (Homann 1991);
7 Fur Formation, Denmark (Fenner 1994);
8 Moreno Gulch, California (Nikolaev et al. 2001);
9 IODP Site 302-2A and 4A (This study).
10, 11. Pterotheca harrensis
10 IODP Site 302-2A and 4A (This study).
11 Reported as Pseudopyxilla harrensis. Fur Formation,
Denmark (Fenner 1994).
a, b. Pterotheca kittoniana var. kamtschatica
a Kronotsk area, Kamchatka, Russia (SheshukovaPoretskaya 1967);
b Western Siberia (Glezer et al. 1974).
c-j. Pterotheca kittoniana var. kittoniana
c-g. Reported as Pterotheca kittoniana.
c Jutland and Mors, Denmark (Van Heurck 18801881);
d Seymour Island, Antarctic Peninsula (Harwood
1988);
e ODP Hole 702B (Fenner 1991);
270
f
DSDP Site 214 (Fenner 1991);
g DSDP Hole 524A (Fenner 1991);
h Mors and Fur Formations, Denmark (Homann 1991);
i Fur Formation, Denmark (Fenner 1994).
j. Reported as Pterotheca aculeifera.
j Western Siberia (Strelnikova 1974).
k. Pterotheca kittoniana var. minuta
k Fur Formation, Denmark (Fenner 1994).
A-D. Pterotheca minuta
A Reported as Pterotheca minuta. A. IODP Site 302-2A
and 4A (This study).
B Reported as Pseudopyxilla minuta. B. Fur Formation,
Denmark (Fenner 1994).
C Reported as Hemiaulus kittonii. C. Mors, Denmark
(Van Heurck 1880-1881).
D Reported as Pterotheca tuffata. D. Fur Formation,
Denmark (Fenner 1994).
E-I. Pterotheca reticulata
E Rekinniki Bay, eastern side of Penzhina Bay,
Kamchatka, Russia and Nituy, Gurovka, and Gornaya
rivers, South Sakhalin, Russia (SheshukovaPoretskaya 1967);
F DSDP Site 348 (Schrader and Fenner 1976);
G DSDP Site 348 (Dzinoridze et al. 1978);
H Szurdokpüspöki diatomite stop, Hungary (Hajós
1986);
I DSDP Site 338 (This study).
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 6
Legend on opposite page.
Liradiscus ? sp. A
Plate 3, figures 38-40
Description: Frustule not observed. Valve elliptical to oval in
valve view, apical axis 20-28µm, pervalvar axis 8-9µm. Valve
hyaline, nearly flat, entire surface covered with net-like veins.
Remarks: It is unknown whether or not this species belongs to
the fossil resting spore morpho-genus Liradiscus of extant
Chaetoceros because its frustule was not observed and we could
not confirm the presence or absence of a single ring of puncta on
the hypovalve.
Odontotropis arctica sp. A
Comparison: This species is similar to Liradiscus species, especially L. pacificus (Suto 2004a) in possessing net-like veins, but
differs from L. pacificus by having a nearly flat valve.
Stratigraphic and geographic distributions: This species was
observed in middle Eocene sediments only from IODP Leg 302
Site 2A-59X-2, 122-123 in the central Arctic Ocean in this
study.
Description: See Suto, Watanabe and Jordan (submitted).
Type level and locality: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species is preserved abundantly
in middle Eocene sediments from the Lomonosov Ridge.
271
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Odontotropis arctica sp. A var. 1 Suto in Suto, Watanabe et Jordan
submitted
Description: See Suto, Watanabe and Jordan (submitted).
Description: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species did not occur in
Lomonosov Ridge sediments.
Type level and locality: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species occurred abundantly in
middle Eocene sediments from the Lomonosov Ridge.
Odontotropis? carinata Grunow 1884
Basionym: Odontotropis ? carinata GRUNOW 1884, p. 59 (with no illustration).
Odontotropis danicus Debes in Hustedt 1930
Description: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species was preserved abundantly in middle Eocene sediments from the central Arctic
Ocean in this study.
Odontotropis galeonis Hanna 1927b
Description: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: In this study, this species was preserved abundantly in middle Eocene sediments from the
Lomonosov Ridge.
Stratigraphic occurrence: This species was not observed in this
study.
Odontotropis cristata Grunow 1884
Odontotropis birostrata Pantocsek 1903
Basionym: Biddulphia ? cristata GRUNOW in VAN HEURCK 18801885, pl. 102, fig. 4.
Basionym: Odontotropis birostrata PANTOCSEK 1903, Bd. 2, pl. 17,
fig. 286, Bd. 3, pl. 14, fig. 214.
TEXT-FIGURE 7 (opposite page)
Geographic and stratigraphic distribution of Trochosira coronata Schrader and Fenner, Trochosira mirabilis Kitton and
Trochosira polychaeta (Strelnikova) Sims.
1-9. Trochosira coronata
1-6. Reported as Trochosira coronata.
1 DSDP Site 338 (Schrader and Fenner 1976);
g ODP Hole 698A (Fenner 1991);
2 DSDP Site 339 (Schrader and Fenner 1976);
h ODP Hole 700B (Fenner 1991);
3 DSDP Site 340 (Schrader and Fenner 1976);
i ODP Hole 702B (Fenner 1991).
4 DSDP Site 338 (Sims 1988);
A-H. Trochosira polychaeta
5 Fur Formation, Denmark (Fenner 1994);
A, B. Reported as Trochosira polychaeta.
A Alpha Ridge, Arctic Ocean (Sims 1988);
6 IODP Site 302-2A and 4A (This study).
7-9. Reported as Trochosira mirabilis
7 DSDP Site 338 (Dzinoridze et al. 1978);
8 DSDP Site 339 (Dzinoridze et al. 1978);
9 DSDP Site 340 (Dzinoridze et al. 1978).
a-i. Trochosira mirabilis
a-e. Reported as Trochosira mirabilis.
a Mors, Denmark (Kitton 1871);
b Mors Formation, Denmark (Van Heurck 1880-1885);
c ‘Kamishev’, eastern slopes of the Ural mountains,
USSR (Sims 1988);
d Mors and Fur Formations, Denmark (Homann 1991);
e Fur Formation, Denmark (Fenner 1994).
272
f-i. Reported as Trochosira cf. or aff. mirabilis.
f Mors and Fur Formations, Denmark (Homann 1991);
B IODP Site 302-2A and 4A (This study).
C-E. Reported as Sceletonema polychaetum.
C Western Siberia (Strelnikova 1971);
D Western Siberia (Strelnikova 1974);
E Alpha Ridge, Arctic Ocean (Barron 1985).
F. Reported as Pyrgodiscus triangulatus.
F DSDP Site 275 (Hajós and Stradner 1975).
G, H. Reported as Trochosiropsis polychaeta.
G Slidre Fjord Section, Canada (Tapia and Harwood
2002);
H Horton River Section, Canada (Tapia and Harwood
2002).
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 7
Legend on opposite page.
Description: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species occurred in middle
Eocene sediments from the Lomonosov Ridge in this study.
Odontotropis hyalina Witt 1886 (= Odontotropis klavsenii Debes)
Description: See Suto, Watanabe and Jordan (submitted).
Stratigraphic occurrence: This species occurred in middle
Eocene sediments from the Lomonosov Ridge in this study.
Peripteropsis ? sp. A
Plate 3, figures 41-52
Description: Frustule isovalvate, apical axis 10-32µm,
transapical axis 5-12µm not including the thin and wide processes. Valve narrowly to broadly elliptical in valve view.
Epivalve hyaline, slightly convex in the center, with numerous
thin and wide processes, with distinct valve mantle. Epivalve
mantle hyaline, high. Hypovalve hyaline, vaulted with one
hump, with numerous thin and wide processes, with distinct
valve mantle. Mantle of hypovalve hyaline. The thin and wide
processes hyaline, flat around the margins of the epi- and
hypovalves, slender processes becoming at their tips and curved
near their apices.
Comparison: This species is characterized by its numerous thin
and wide processes around the margins of the epi- and
hypovalves, slender processes becoming at their tips. This spe-
273
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
cies is separated from Peripteropsis norwegica Suto (2005b) by
lacking branched thin and wide processes.
Stratigraphic and geographic distributions: This species occurred in middle Eocene sediments from IODP Leg 302 Sites
2A and 4A in the central Arctic Ocean.
Remarks: This species does not appear to belong to the fossil
resting spore morpho-genus Peripteropsis of extant
Chaetoceros because of the absence of a ring of puncta on the
hypovalve margin.
Porotheca danica (Grunow) Fenner 1994
Plate 7, figures 1-28
Porotheca danica (Grunow) FENNER 1994, p. 114, pl. 4, figs. 16, 17;
pl. 15, figs. 1-6.
Basionym: Stephanogonia (Pterotheca?) danica GRUNOW in VAN
HEURCK 1880-1885, pl. 83 bis., figs. 7, 8.
References: Stephanogonia danica GRUNOW 1866, p. 146. – CLEVEEULER 1951, Handl. 2: 1, p. 110, figs. 232a, b. – HOMANN 1991, p.
141, pl. 55, figs. 7, 9-16.
Synonymy: Pyxilla carinifera var. russica PANTOCSEK 1905, Bd. 3,
pl. 35, fig. 491; Bd. 3, pl. 29, fig. 423.
Pterotheca danica GRUNOW, HANNA 1927a, p. 119, pl. 20, fig. 11. –
PROSCHKINA-LAVRENKO 1949, p. 203, pl. 75, fig. 9. – HAJÓS
1976, p. 829, pl. 16, figs. 12-15. – GOMBOS 1977, p. 596, pl. 23, fig.
5. – LEE 1993, p. 42, pl. 3, fig. 4. – DELL’AGNESE and CLARK
1994, fig. 9.11.
Pterotheca cf. aculeifera Grunow sensu HAJÓS and STRADNER 1975,
p. 933, pl. 28, figs. 1, 2 nec pl. 12, fig. 6.
Pterotheca carinifera Grunow in VAN HEURCK sensu MCCOLLUM
1975, p. 535, pl. 10, fig. 4 nec pl. 16, figs. 6, 7.
Pterotheca danica (Grunow) FORTI 1909, p. 13. – GOMBOS 1983, p.
570, pl. 3, fig. 9. – GOMBOS and CIESIELSKI 1983, p. 603, pl. 13,
figs. 1-3, 9. – BARRON et al. 1984, p. 156, pl. 8, fig. 10. – BALDAUF
1985, p. 464, pl. 12, figs. 8, 9. – HARWOOD 1988, p. 86, fig. 18.12. –
DESIKACHARY and SREELATHA 1989, p. 218, pl. 100, figs. 1, 2,
5.
Pterotheca major JOUSÉ 1955, p. 101, text-fig. 1; pl. 6, fig. 2. –
GOMBOS 1983, p. 570. – GOMBOS and CIESIELSKI 1983, p. 603,
pl. 13, figs. 6-8. – HARWOOD 1988, p. 86, fig. 18.16.
Pterotheca spada TEMPÈRE et BRUN sensu GOMBOS and
CIESIELSKI 1983, p. 603, pl. 13, figs. 4, 5.
Pterotheca (Grunow) FORTI sensu HARGRAVES 1984, p. 71, figs.
14-16.
Pterotheca carinifera (Grunow in Van Heurck) FORTI sensu HARWOOD 1988, p. 86, fig. 18.6.
Stephanogonia novazelandica Grunow sensu DESIKACHARY and
SREELATHA 1989, p. 228, pl. 100, figs. 3, 4.
Pyxilla? carinifera Grunow sensu HOMANN 1991, p. 139, pl. 55, fig. 6
nec figs. 1-5, 8.
Pterotheca carinifera Grunow sensu HARWOOD and BOHATY 2000,
p. 93, pl. 3, fig. t; pl. 9, fig. o.
Emended description: Epivalve convex, cylindrical with a high
mantle, diameter 13-45µm, transapical axis 30-65µm. The central part of epivalve face protracted forming a hollow tube with
a flat top. Epivalve surface generally structured by seven to
TEXT-FIGURE 8
Geographic and stratigraphic distribution of Trochosira spinosa Kitton.
1-25. Trochosira spinosa
15 Fur Formation, Denmark (Fenner 1994);
1-17. Reported as Trochosira spinosa.
1 Mors, Denmark (Kitton 1871);
16 ODP Hole 908A (Scherer and Koç1996);
2 Mors Formation, Denmark (Van Heurck 1880-1885);
3 Lower course of the Anadyr River, Russia (Sheshukova-Poretskaya 1967);
4 DSDP Site 173 (Schrader 1973a);
5 west Kazakhstan (Glezer et al. 1974);
6 DSDP Site 337 (Schrader and Fenner 1976);
7 DSDP Site 338 (Schrader and Fenner 1976);
8 DSDP Site 339 (Schrader and Fenner 1976)
9 DSDP Site 343 (Schrader and Fenner 1976);
10 DSDP Site 338 (Dzinoridze et al. 1978);
11 DSDP Site 339 (Dzinoridze et al. 1978);
12 DSDP Site 340 (Dzinoridze et al. 1978);
13 Hawthorn Formation, South Carolina (Abbott and
Andrews 1979);
14 Mors and Fur Formations, Denmark (Homann 1991);
274
17 DSDP Site 338 (This study).
18, 19. Reported as Trochosira spinosus.
18 Jutland, Denmark (Sims 1988);
19 Cape Roberts Project, Antarctica (Scherer et al.
2000).
20. Reported as Trochosira spinosa?
20 McMurdo Sound, Antarctica (Harwood and Bohaty
2000).
21, 22. Reported as Trochosira ornata.
21 Jutland, Denmark (Van Heurck 1880-1885);
22 Fur Formation, Denmark (Fenner 1994).
23. Reported as Sceletonema ornatum.
23 eastern slopes of Ural Mountains, USSR (Jousé
1955).
24. Reported as Sceletonema spinosum.
24 eastern slopes of Ural Mountains, USSR (Jousé
1955).
25. Reported as Trochosira coronata.
25 ODP Hole 913B (Scherer and Koç 1996).
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 8
Legend on opposite page.
eight radial hyaline ridges from the edge between the mantle
and the valve face to the elevated central top. Radial hyaline
ridges with arranged knobs and short spines on it, and smaller
anastomosing hyaline ridges present between these ridges.
Mantle hyaline, perforated by small pores and small hyaline
anastomosing ribs. The pore which is present on the top of the
central raised platform (Fenner 1994) was not observed in this
study. Hypovalve is featureless, with a raised rim and concave
central area, occasionally with a slightly central elevation (see
figure 14 in Hargraves 1984), although frustule was not observed in this study.
Type level and locality: Lower Eocene, Mors Formation in
Jutland, Denmark (Grunow in Van Heurck 1880-1885).
Type specimen: Depository not designated.
Comparison: This species is very similar to Kentrodiscus
blandus Long, Fuge et Smith (1946) of Nikolaev et al. (2001, p.
25, pl. 36, figs. 1-5), which was found in late Cretaceous marine
deposits in the Marca Shale Member, California. Both species
have a cylindrical highly vaulted valve shape with a flat top possessing a slit in the central part. In Nikolaev et al. (2001), the
specimens are illustrated with a nearly flat hypovalve covered
with numerous short strong spines. The genus Kentrodiscus
Pantocsek (1903), which contains some species from the late
Cretaceous, for example, K. fossilis Pantocsek (1903), K.
aculeatus Hanna (1927b), K. andersoni Hanna (1927b) and K.
armatus Hajós in Hajós and Stradner (1975), is characterized by
having valves protracted to form a hollow tube with a flat top
with numerous strong spines on the epi- and hypovalve faces.
Kentrodiscus blandus lacks spines on the epivalve surface, but
has radially arranged hyaline ridges which run from the edge
275
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
between the mantle, therefore K. blandus may belong to the genus Porotheca although the hypovalve structure of Po. danica
is unknown.
This species is also similar to Pseudopyxilla carinifera in that
the valve shape forms a hollow tube with radially arranged
hyaline ridges running from the flat top to mantle edge, but it
differs from the latter by its larger valve size and the possession
of hyaline ridges with knobs and spines on it. Pterotheca
pokrovskajae Jousé sensu Harwood (1988, p. 86, figs. 12.9-10,
18.19-23) may be distinguished from Po. danica by the lack of
abundant pores on its valve.
Stratigraphic and geographic distributions: This species was
frequently found in late Cretaceous to early Miocene sediments
(Text-figure 3). This species was found in late Cretaceous and
early Paleocene sediments from Seymour Island, Antarctic
Peninsula (Harwood 1988), from late Cretaceous DSDP Site
275 sediments at the southeast margin of Campbell Plateau near
New Zealand (Hajós and Stradner 1975), and from the Alpha
Ridge, Arctic Ocean (Dell’Agnese and Sreelatha 1989). With
regards to Eocene sediments, this species has been reported
from all parts of the world including the IODP Expedition 302,
central Arctic Ocean, however it was also found in the Southern
Hemisphere in Oligocene sediments and from the high latitude
Pacific Ocean in early Miocene deposits.
Etymology: Not designated. – but presumably refers to Denmark.
Pseudopyxilla carinifera (Grunow in Van Heurck) Suto, Jordan et
Watanabe comb. nov.
Basionym: Pyxilla ? carinifera GRUNOW in VAN HEURCK
1880-1885, pl. 83, fig. 5, 6. – HOMANN 1991, p. 139, pl. 55, figs. 1-5,
nec figs. 6, 8.
Synonymy: Pterotheca carinifera (GRUNOW in VAN HEURCK)
FORTI 1909, p. 13. – DESIKACHARY and SREELATHA 1989, p.
218, pl. 142, fig. 10.
Pterotheca carinifera GRUNOW, HANNA 1927a, p. 119, pl. 20, figs.
9, 10. – PROSCHKINA-LAVRENKO 1949, p. 203, pl. 75, figs. 7a, b;
pl. 77, fig. 1; pl. 98, fig. 8. – SHESHUKOVA-PORETSKAYA 1967,
p. 270. – GOMBOS 1976, p. 596, pl. 23, figs. 1, 2.
Pyxilla (Rhizosolenia?) carinifera Grunow sensu CLEVE-EULER
1951, Handl. 2: 1, p. 93, fig. VI-p.
Pterotheca carinifera var. curvirostris JOUSÉ 1955, p. 99, pl. 2, fig. 7. –
HARWOOD 1988, p. 86, fig. 18.7.
Pterotheca carinifera GRUNOW in VAN HEURCK – MCCOLLUM
1975, p. 535, pl. 16, figs. 6, 7 nec pl. 10, fig. 4.
Pterotheca carinifera (Grunow) FORTI – SCHRADER and FENNER
1976, p. 994, pl. 9, fig. 6; pl. 43, fig. 12. – LEE 1993, p. 42, pl. 1, fig.
19; pl. 2, fig. 17 nec pl. 3, fig. 10. – FENNER 1994, p. 116.
Pterotheca minor HARWOOD 1988, p. 86, figs. 12.12, 13. – HARWOOD and BOHATY 2000, p. 93, pl. 3, figs. r, s.
Description: Epivalve convex, cylindrical with a high mantle,
diameter 7-22µm, transapical axis 10-70µm. The central part of
epivalve face protracted to form a hollow tube with a flat top.
Epivalve surface generally structured by four radial hyaline
ridges from the edge between the mantle and the valve face to
the elevated central top, hyaline between radial hyaline ridges.
Mantle distinct and hyaline. Hypovalve nearly flat and featureless (see pl. 55, figure 2 in Homann 1991), although frustule
was not observed in this study.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not given.
276
Comparison: This species is easily distinguished from Porotheca danica by its more slender valve and its possession of
hyaline ridges lacking knobs and spines. This species also resembles Pterotheca spada (= Pt. subulata) and Pseudopyxilla
capreolus in possessing a hollow tube on its epivalve, but is
identified from the former by its nearly flat hypovalve and from
the latter by lacking a dichotomous branching hyaline process at
the distal end of the hollow tube.
Stratigraphic and geographic distributions: This species occurs
from the late Cretaceous to the late Miocene (Text-figure 3).
This species was not observed in this study.
Remarks: This species is characterized by its hyaline cylindrical
to conical valve, therefore this species was transferred to the genus Pseudopyxilla in this study. When Fenner (1994) erected
the genus Porotheca, she mentioned that it is characterized by
cylindrical to conical valves with a central elevation with a
pore-like opening on top. It is unknown whether or not Ps.
carinifera possesses such a pore-like opening, however its
stratigraphic and geographic distributions resemble closely
those of Po. danica, therefore Ps. carinifera may belong to the
genus Porotheca and be a variety of Po. danica.
The specimens of Pterotheca carinifera in Harwood (1988, p.
86, fig. 18.6), Harwood and Bohaty (2000, p. 93, pl. 3, fig. t; pl.
9, fig. o) and McCollum (1975, p. 535, pl. 16, figs. 6, 7 nec pl.
10, fig. 4), and of Pyxilla? carinifera in Homann (1991, p. 139,
pl. 55, figs. 6, 8 nec figs. 1-5) are identified as Porotheca danica
because their large valves with hyaline ridges are covered with
knobs and spines. The specimen of Pterotheca carinifera in Lee
(1993, p. 42, pl. 3, fig. 10 nec pl. 1, fig. 19; pl. 2, fig. 17) is
Pterotheca subulata.
Etymology: The Latin carinifera means “coarse keel”.
Pseudopyxilla dubia (Grunow in Van Heurck) Forti 1909
Plate 8, figures 1-21
Pseudopyxilla dubia (Grunow) FORTI 1909, pl. 1, figs. 1-3. – HAJÓS
1968, p. 136, pl. 38, figs. 2, 3. – HANNA 1970, p. 191, figs. 66, 68. –
SCHRADER and FENNER 1976, pl. 44, figs. 13, 14. – FENNER
1978, p. 526, pl. 14, fig. 9; pl. 17, figs. 1-6. – GOMBOS and
CIESIELSKI 1983, p. 603. – GOMBOS 1984, p. 500, pl. 2, figs.
10-12. – FENNER 1994, p. 115, pl. 9, fig. 12. – HARWOOD and
BOHATY 2000, pl. 4, fig. d.
Pseudopyxilla dubia Grunow – PROSCHKINA-LAVRENKO 1949, p.
200, pl. 73, fig. 13; pl. 98, figs. 1a, b.
Pseudopyxilla dubia (Grunow in Van heurck) FORTI – BARRON
1975, p. 152, pl. 11, fig. 13. – HARWOOD 1988, p. 85, figs. 17.23, 24.
Basionym: Pyxilla? dubia Grunow in VAN HEURCK 1880-1885, pl.
83, figs. 7, 8.
References: Pyxilla dubia Grunow in VAN HEURCK 1880-1885, pl.
83, fig. 12. – HASEGAWA 1977, p. 87, pl. 21, fig. 4. – DESIKACHARY and SREELATHA 1989, p. 219, pl. 93, figs. 3-6, 15.
Pyxilla dubia Grunow – HANNA 1927a, p. 119, pl. 20, fig. 13.
Pyxilla (Rhizosolenia?) dubia Grunow in CLEVE-EULER 1951, Handl.
2: 1, p. 93, figs. VI-n.
Pyxilla (Pyxilla) dubia Grunow ex VAN HEURCK sensu KANAYA
1957, p. 114, pl. 8, fig. 10.
Rhizosolenia dubia (Grunow) HOMANN 1991, p. 69, figs. 1-8, 11-13.
Synonymy: Rhizosolenia americana Ehrenberg sensu EHRENBERG
1854, pl. 18, figs. 98a, h, i nec figs. 98b-g.
Pseudopyxilla americana (Ehrenberg) FORTI sensu HAJÓS and
STRADNER 1975, p. 933, pl. 12, fig. 3.
Pyxilla ? baltica Grunow in VAN HEURCK 1880-1885, pl. 83, figs. 1,
2.
Pyxilla baltica Grunow in VAN HEURCK 1880-1885, pl. 83 bis., fig. 4.
Micropaleontology, vol. 55, nos. 2-3, 2009
TEXT-FIGURE 9
Generalized biostratigraphic ranges of diatom resting spore morpho-species from the early to middle Eocene cores in the central Arctic Ocean and their
allied species. Black and gray lines mean the occurrences from sediments in the Northern and Southern Hemispheres, respectively. Star symbols mean
that the specimens may be vegetative cells. Species enclosed with squares were not observed in the IODP Expedition 302 samples. The biostratigraphic
data of genera Goniothecium and Odontotropis are modified after Suto et al. (2008 and submitted).
Pseudopyxilla baltica (Grunow) FORTI 1909, pl. 1, figs. 8, 9. –
PROSCHKINA-LAVRENKO 1949, p. 201, pl. 98, figs. 6a-c. –
SCHRADER and FENNER 1976, p. 994, pl. 44, figs. 3, 6, 9.
Pseudopyxilla baltica (?)(Grunow) FORTI – HARWOOD and
MARUYAMA 1992, p. 705, pl. 2, figs. 9, 10.
Pyxilla russica PANTOCSEK 1905, Bd. 3, pl. 19, fig. 277. –
DESIKACHARY and SREELATHA 1989, p. 220, pl. 93, fig. 12.
Pseudopyxilla russica (Pantocsek) Forti sensu HANNA 1927b, p. 27,
pl. 4, fig. 4. – PROSCHKINA-LAVRENKO 1949, p. 200, pl. 97, fig.
7; pl. 75, fig. 3. – HAJÓS and STRADNER 1975, p. 933, pl. 12, figs.
1, 2; pl. 27, fig. 9. – FENNER 1994, p. 115. – NIKOLAEV et al. 2001,
p. 24, pl. 35, figs. 1, 2.
Pseudopyxilla rossica (Pantocsek) FORTI 1909, p. 14, pl. 1, fig. 13. –
SHESHUKOVA-PORETSKAYA 1967, p. 261, pl. 39, figs. 1a, b. –
STRELNIKOVA 1974, p. 111, pl. 56, figs. 6-8. – SCHRADER and
FENNER 1976, p. 994, pl. 12, figs. 19, 20; pl. 44, figs. 2, 4, nec pl. 44,
fig. 5. – HARWOOD 1988, p. 86, figs. 17.28, 29. – HOMANN 1991,
p. 134, pl. 54, fig. 12.
Pseudopyxilla rossica (?) – SCHRADER and FENNER 1976, p. 994, pl.
12, figs. 19, 20; pl. 44, figs. 2, 4 nec pl. 44, fig. 5.
Pyxilla hungarica PANTOCSEK 1905, Bd. 3, pl. 26, fig. 392.
Pseudopyxilla hungarica (Pantocsek) FORTI 1909, p. 14. – HARWOOD 1988, p. 85, figs. 17.26, 27.
Pyxilla vasta PANTOCSEK 1905, Bd. 3, pl. 40, fig. 551.
Pseudopyxilla tempereana FORTI 1909, p. 15, pl. 1, fig. 11. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 98, fig. 2. – GLEZER
et al. 1974, pl. 53, fig. 11. – FENNER 1991. p. 139, pl. 9, fig. 3. –
FENNER 1994, p. 115.
Pseudopyxilla peragallorum FORTI 1909, p. 16, pl. 1, fig. 10. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 97, fig. 6.
Pseudopyxilla obliquepileata FORTI 1909, p. 17, pl. 1, fig. 12. –
PROSCHKINA-LAVRENKO 1949, p. 200, pl. 98, figs. 3a-b.
Pyxilla (Rhizosolenia?) antiqua CLEVE-EULER 1951, Handl. 2: 1, p.
93, figs. 167, VI-o.
Pseudopyxilla sp. of FENNER 1978, p. 526, pl. 17, fig. 7. – FENNER
1991, p. 139, pl. 9, fig. 4. – NIKOLAEV et al. 2001, p. 24, pl. 35, fig. 3.
277
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Rhizosolenia setigera Brightwell sensu HOMANN 1991, p. 71, pl. 35,
figs. 9, 10.
Description: Frustule heterovalvate. In valve view, valve circular, convex in the middle. Valve surface hyaline or covered with
numerous dense and minute puncta. In girdle view, valve convex, cylindrical with a high mantle, 5-70µm in diameter. Height
of valve is variable, nearly 1 to 7 times its diameter. Mantle distinct and all surface hyaline or hyaline near the top or bottom of
mantle with numerous puncta on lower area. Opposite valve
circular, convex in the middle, sometimes preserved with a delicate crown which are covered with dense and minute puncta.
Valve surface hyaline or covered with numerous dense and
minute puncta. In girdle view, valve convex, cylindrical with a
high mantle. Height of valve is variable, nearly 1 to 7 times its
diameter. Mantle distinct, entire surface hyaline or hyaline near
the top or bottom of mantle with numerous puncta on lower
area. It is unknown which of the valves is the epivalve or
hypovalve in this study.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not designated.
Comparison: This species is very similar to other Pseudopyxilla species like Ps. aculeata and Ps. directa in having cylindrical and conical valves, and Ps. americana, Ps. capreolus and
Ps. jouseae in having cylindrical valves, but is differentiated
from the former two species by its lower convex valve, and
from the latter three species by the absence of a branching process on the valve top.
Stratigraphic and geographic distributions: This species is cosmopolitan and a long-ranged species from the late Cretaceous
through to the Pliocene (Text-figure 4).
Remarks: Several species which possess highly cylindrical and
convex valves that are hyaline or covered with numerous dense
puncta have been described as Ps. baltica, Ps. dubia, Ps.
hungarica, Ps. obliquepileata, Ps. peragallorum, Ps. russica
(sometimes misspelled rossica) and Ps. tempereana. These species may be separated by the presence or absence of puncta on
the valve mantle and by differences in the height of the holotype
specimens. Another confusion may have been caused by the difficulty in identifying specimens which are preserved in the sediments as separated valves (such as only one valve or an opposite
valve with/without a crown). However several forms with/without puncta were observed in middle Eocene IODP Leg 302 samples (at one site) and most of the stratigraphic and geographic
distributions of these species are cosmopolitan and long-ranged
indicating little differences between them (Text-figure 4).
Therefore we assumed that these species belong to a single or
are varieties of one species.
According to Homann (1991), the resting spore type “Pseudopyxilla” belongs to species related to the genus Rhizosolenia,
because Homann (1991) found that the vegetative cells look like
Rhizosolenia and are very different from resting spores. Thus
most relationships between these different frustule types remain
unknown. Therefore the resting spore morpho-genus Pseudopyxilla is here maintained. The Rhizosolenia-like vegetative
valves are also illustrated in Proschkina-Lavrenko (1949).
Moreover, Marino et al. (1991) also hypothesized that the fossil
species Pyxilla dubia has a closer affinity to the genus
Chaetoceros than to the genus Rhizosolenia based on the origi-
PLATE 1
Anaulus arcticus sp. nov.
All figures are transmitted light micrographs (LM). Scale bar = 10µm, which applies to all figures.
1,2 Holotype. IODP Site 302-2A-61X-2, 2-3cm. Girdle
view of paired valves.
18,19 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
3,4 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
paired valves.
20,21 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
5,6 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
paired valves.
22,23 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
7,8 IODP Site 302-2A-55X-CC. Girdle view of paired
valves.
24,25 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
paired valves.
9,10 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
paired valves.
26,27 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
11,12
IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
paired valves.
28,29 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
frustule.
13-15 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
30,31 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule connected to hypovalve of opposite valve.
16,17 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
paired valves.
278
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 1
279
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
nal drawing of Forti (1909). Sometimes valves are preserved
with a delicate crown covered with dense puncta (see Van
Heurck 1880-1885, Desikachary and Sreelatha 1989). From
their illustrations, the crown on some spore valves may represent preserved vegetative cells.
Etymology: The Latin dubia means “uncertain”.
Pseudopyxilla jouseae Hajós in Hajós and Stradner 1975
Plate 8, figures 22-31
Pseudopyxilla jouseae HAJÓS in HAJÓS and STRADNER 1975, p.
933, pl. 12, figs. 4, 5.
Synonym: Pterotheca sp. (aff. carinifera Grunow) of JOUSÉ 1951, p.
59, pl. 4, fig. 4.
Emended description: Frustule heterovalvate. In valve view,
valve circular. Valve surface hyaline, covered with numerous
wrinkles and nearly straight ridges from the top of the conical
area to the mantle margin. In girdle view, valve 5-20µm in di-
ameter, cylindrical with a high mantle, conical at one end, and
extending into a long tapered spine. The tapered spine bifurcated at the end (see pl. 8, fig. 30). Height of valve is variable,
nearly 1 to 4 times its diameter not including the conical area
with long tapered spine. Mantle distinct, covered with numerous wrinkles. Opposite valve (perhaps hypovalve) circular, convex (see pl. 8, figs. 26, 27).
Type level and locality: Upper Cretaceous. DSDP Site 275 (lat.
50° 26.34’ S, 176° 18.99’ E) in 2,837 m water depth on the eastern edge of the Campbell Plateau to the southwest of the Bounty
Islands, South Pacific; in sample 1-1, 118-120cm.
Type specimen: Deposited in the collections of the Hungarian
Geological Survey, Budapest; holotype (figs. 4, 5), no. 2799/1.
Comparison: This species is characterized by a conical and cylindrical valve covered with wrinkles, and a long tapered and bifurcating spine.
PLATE 2
Anaulus arcticus sp. nov.
Figures 1-35 are LM and figs. 36-47 are SEM, respectively. The scale bar in fig. 1 is 10µm and it also applies to figs. 2-35.
The scale bars in figs. 36-47 are 10µm.
1 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
2,3 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
4-6 IODP Site 302-2A-59X-CC, 0-1cm. Frustule in valve
view.
7,8 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
9,10 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
11,12 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
13,14 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
15,16 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
17,18 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
19,20 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
37 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
38 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
39 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve.
40 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve.
41 IODP Site 302-4A-5X-1, 2-3cm. Inner valve view of
epivalve
42 IODP Site 302-4A-5X-1, 2-3cm. Oblique valve view
of hypovalve.
43 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
21,22 IODP Site 302-4A-6X-2, 2-3cm. Valve view.
23,24 IODP Site 302-4A-7X-1, 2-3cm. Valve view.
25-27 IODP Site 302-4A-5X-1, 2-3cm. Valve view.
28,29 IODP Site 302-4A-5X-1, 2-3cm. Valve view.
30,31 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
32,33 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
34,35 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
36 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
280
44 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
hypovalve.
45 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
hypovalve.
46 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
paired valves.
47 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view
of frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 2
281
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Stratigraphic and geographic distributions: Hajós and Stradner
(1975) reported this species from the late Cretaceous cores of
DSDP Site 275 and this species was observed in middle Eocene
cores of IODP Leg 302 in this study (Text-figure 4).
Etymology: This species was named in honor of Dr. A. P. Jousé.
Pterotheca aculeifera Grunow in Van Heurck 1880-1885 (= Pterotheca crucifera Hanna 1927b)
Plate 9, figures 1-47
Basionym: Pterotheca (Pyxilla ??) aculeifera GRUNOW in VAN
HEURCK 1880-1885, pl. 83 bis, fig. 5.
References: Pterotheca aculeifera GRUNOW, VAN HEURCK 1896,
p. 430, fig. 151. |PROSCHKINA-LAVRENKO 1949, p. 202, pl. 75,
fig. 4b nec fig. 4a. – SHESHUKOVA-PORETSKAYA 1967, p. 266. –
GLEZER et al. 1974, pl. 12, fig. 5. – STRELNIKOVA 1974, p. 114,
pl. 57, figs. 1-16, 23-26 nec figs. 17-22 – GOMBOS 1977, p. 596, pl.
23, figs. 1, 2. – SCHRADER and FENNER 1976, p. 994, pl. 43, figs.
1-4. – FENNER 1978, p. 527, pl. 17, figs. 8-21. – DZINORIDZE et al.
1978, pl. 9, fig. 6. – GOMBOS 1983, p. 570. – GOMBOS and
CIESIELSKI 1983, p. 603. – GOMBOS 1984, p. 500. – SANFILIPPO
and FOURTANIER 2003, pl. 3, fig. 7. – TSOY 2003, pl. 1, fig. 7.
Pterotheca aculeifera Grunow in VAN HEURCK 1896, p. 430, fig. 151.
– HAJÓS 1976, p. 829, pl. 16, figs. 6-8. – SCHERER and KOÇ 1996,
p. 86, pl. 8, fig. 11. – TAPIA and HARWOOD 2002, p. 328.
Pterotheca aculeifera (Grunow) VAN HEURCK – BALDAUF 1985, p.
464, pl. 10, figs. 13, 14. – FENNER 1994, p. 116, pl. 4, fig. 8.
Pterotheca aculeifera (Grunow in VAN HEURCK) VAN HEURCK –
HARWOOD 1988, p. 86, figs. 18.3, 4. – DESIKACHARY and
SREELATHA 1989, p. 218, pl. 93, fig. 11.
Pterotheca aculeifera (Grunow) GRUNOW em. HOMANN 1991, p.
135, pl. 35, figs. 15-18. – HARWOOD and BOHATY 2000, p. 93, pl.
1, fig. l; pl. 9, fig. p.
PLATE 3
Figures 1-22, 24-36, 38, 39, 41-52 are LM and figs. 23, 37, 40 and 53 are SEM, respectively.
The scale bars in figs. 1 and 2, and 24 and 25 are 10µm and those also apply to figs. 3-22 and 41-52, and 26-33, respectively.
The scale bars in figs. 23, 37, 38 and 39, 40 and 53 are 10µm, respectively.
1-23. Resting spore sp. C.
1,2 IODP Site 302-2A-54X-CC. Girdle view of frustule.
3,4 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
5,6 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
7,8 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
9,10 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
11,12 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
13,14 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
15,16 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
17,18 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
19,20 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
21,22 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
23 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
24-37. Costopyxis trochlea (Hanna) Strelnikova in Glezer et al.
24,25 DSDP Leg 38, Site 338-29-1, 130-131cm. Girdle
view of frustule.
26,27 DSDP Leg 38, Site 338-29-1, 130-131cm. Girdle
view.
282
28 DSDP Leg 38, Site 338-29-1, 130-131cm. Valve
view.
29,30 IODP Site 302-2A-54X-CC. Girdle view.
31-33 IODP Site 302-2A-61X-2, 2-3cm. Girdle view.
34-36 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
37 IODP Site 302-4A-5X-1, 2-3cm. Girdle view.
38-40. Liradiscus ? sp. A.
38,39 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
40 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
41-53. Peripteropsis ? sp. A.
41,42 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
43,44 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
45,46 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
47,48 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
49,50 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
51,52 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
53 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view
of frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 3
283
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Synonymy: Pyxilla ?? aculeifera Grunow in VAN HEURCK
1880-1885, pl. 83, figs. 13, 14.
Pterotheca crucifera HANNA 1927b, p. 30, pl. 4, fig. 5. –
PROSCHKINA-LAVRENKO 1949, p. 202, pl. 98, fig. 7. – HAJÓS
and STRADNER 1975, p. 934, pl. 12, figs. 8, 9, 22; pl. 27, fig. 7; pl.
28, fig. 3. – HARWOOD 1988, p. 86, fig. 18.5. – NIKOLAEV et al.
2001, p. 26, pl. 39, figs. 8, 9.
Pyxilla (Rhizosolenia?) aculeifera Grunow sensu CLEVE-EULER
1951, Handl. 2: 1, p. 93, figs. 168a-d, VI-r.
Pyxilla (Pterotheca) aculeifera (Grunow ex Van Heurck) sensu
KANAYA 1957, p. 109, pl. 8, figs. 1, 2.
Pterotheca uralica JOUSÉ sensu STRELNIKOVA 1974, p. 115, pl. 57,
figs. 27-30a, b. – FENNER 1978, p. 527, pl. 17, fig. 22.
Pterotheca sp. 2 in MCCOLLUM 1975, p. 535, pl. 10, fig. 10.
Pterotheca sp. A in GOMBOS 1977, p. 526, pl. 23, figs. 3, 4. – HARWOOD and BOHATY 2000, p. 93, pl. 9, figs. l-n.
Pterotheca sp. 1 in FENNER 1991, p. 139, pl. 2, fig. 10.
Pseudopyxilla americana sensu DELL’AGNESE and CLARK 1994,
fig. 4.6.
Description: Frustule heterovalvate, apical axis 4-15µm,
pervalvar axis of epivalve 8-17µm not including the spine. In
valve view, valve shape circular. In girdle view, epivalve
strongly convex or inflated with about 10 coarse, weak or
strong siliceous ridges extending from the margin to the apex,
interspaces hyaline, sometimes these ridges not developed
(Simple type; see Plate 9, Figs. 44-47). Apex crowned with a
huge spine (sometimes two, double spiny type; see Plate 9, Figs.
41-43) apparently square in shape and with sharp keels on each
corner. Keels extending down over the conical portion for a
short distance, two heavy sides, wing-like projections are developed near the top of the spine and connected with each other.
Mantle of epivalve distinct and hyaline. Hypovalve slightly
convex and hyaline. Mantle of hypovalve distinct and hyaline.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not designated.
Comparison: This species is very similar to Pt. kittoniana by
having siliceous ridges extending from the margin to the apex
but is distinguished from the latter by its huge spines with
wing-like projections on the valve apex. This species also resembles Pt. evermanii as both possess a branching process on
their valve tops, but can easily be separated from the latter by its
strongly inflated rather than conical valve shape and its valve
surface with siliceous ridges.
Stratigraphic and geographic distributions: The first occurrence of this species is unknown, but the oldest is known from
PLATE 4
Figures 1-38, 40-45 are LM and fig. 39 is SEM, respectively.
The scale bars in figs. 1 and 2 is 10µm and it also applies to figures 3-38 and 40-45. The scale bar in fig. 39 is 10µm.
1-39. Resting spore sp. D
1,2 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
3,4 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
5,6 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
7,8 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
9,10 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
11,12 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of frustule.
13,14 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
epivalve.
15,16 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
284
23,24 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
25,26 IODP Site 302-2A-54X-CC. Girdle view of frustule.
27,28 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
hypovalve.
29,30 ODP Site 302-2A-52X-2, 2-3cm. Valve view of
hypovalve.
31,32 IODP Site 302-4A-7X-1, 2-3cm. Valve view of
hypovalve.
33,34 IODP Site 302-2A-52X-2, 2-3cm. Valve view of
hypovalve.
35,36 IODP Site 302-2A-54X-CC. Epivalve view of
frustule.
37,38 IODP Site 302-4A-6X-2, 2-3cm. Hypovalve view of
frustule. 39. IODP Site 302-4A-5X-1, 2-3cm. Girdle
view of frustule.
17,18 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
40-45. Dispinodiscus ? sp. A
40,41 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
19,20 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
42,43 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
21,22 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
44,45 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 4
285
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
the late Cretaceous (Text-figure 6). The reported last occurrences of this species are in the early Oligocene from sediments
of DSDP Site 511 (Gombos and Ciesielski 1983) and ODP hole
1128C (Sanfilippo and Fourtanier 2003).
Remarks: The fossil closest in appearance to this diatom was
described by Hanna (1927b, p. 30, pl. 4, fig. 5) from the
Moreno Shale in California, upper Cretaceous, as Pterotheca
crucifera Hanna. He discriminated the species from Pt.
aculeifera because it has a “shorter valve” and “much heavier
radiating ridges”. However, Pt. crucifera is identified as Pt.
aculeifera in this study, because their valve shapes and sizes are
dependent on the capacities of their vegetative valves.
Pterotheca aculeifera in Proschkina-Lavrenko (1949, p. 202,
pl. 75, fig. 4a), Jousé (1963, figs. 111, 114) and Strelnikova
(1974, p. 114, pl. 57, figs. 17-22) belong to Pt. kittoniana because they lack a branching process on their valve tops and siliceous ridges on their valve surfaces. Pterotheca cf. aculeifera
in Hajós and Stradner (1975, p. 933, pl. 12, fig. 6) and
Pterotheca sp. cf. P. crucifera in Harwood (1988, p. 86, figs.
12.14, 15) look like a species in the genus Monocladia Suto, but
the first occurrence of the genus Monocladia is reported from
latest Oligocene in the Atlantic Ocean (Suto 2005c). Therefore,
these specimens might be Pterotheca spp. Other specimens of
Pterotheca cf. aculeifera in Hajós and Stradner (1975, p. 933,
pl. 28, figs. 1, 2) are identical to Porotheca danica because of
their valve shapes.
Etymology: The Latin aculeifera means “rough spines”
Pterotheca evermanii Hanna 1927b
Plate 8, figures 32-50
Pterotheca evermanii HANNA 1927b, p. 31, pl. 4, fig. 6. –
PROSCHKINA-LAVRENKO 1949, p. 203, pl. 98, fig. 9. – GLEZER
et al. 1974, pl. 12, fig. 4. – STRELNIKOVA 1974, p. 112, pl. 56, figs.
12-15. – HARWOOD 1988, p. 86, fig. 18.13, 14. – FENNER 1991, p.
139, pl. 2, fig. 13. – HOMANN 1991, p. 137, pl. 53, figs. 21-23. –
FENNER 1994, p. 116, pl. 4, fig. 9. – NIKOLAEV et al. 2001, p. 26, pl.
39, figs. 6, 7.
Synonymy: Pterotheca sp. in JOUSÉ 1963, fig. 113.
Pseudopyxilla sp. in HARWOOD 1988, p.86, fig. 17.25.
Description: Frustule heterovalvate, diameter 5-20µm, transapical axis of epivalve 6-20µm excluding the spines. In valve
view, valve shape circular. In girdle view, epivalve highly cylindrical, hyaline. Epivalve surface thick and heavy with one or
two huge spines on the top, at the upper end of which there are
several irregular branches. Length of each valve varies considerably in proportion to diameter and the arrangement of the
branched spine is not uniform, although in all the specimens observed so far the branching portion is about the same distance
from the tip of the spine; the spine is bent slightly away from the
axis. Mantle of epivalve distinct, high and hyaline. Hypovalve
slightly convex or nearly flat and hyaline. Mantle of hypovalve
not distinct and hyaline. Diameter of holotype, 20µm.
Type level and locality: Upper Cretaceous (Maastrichtian), upper Moreno Shale in the upper half of a 200 foot thick
diatomaceous shale near the top of the formation in Moreno
Gulch, Panoche Hills, northwestern Fresno County, California.
Type specimen: Deposited in the collections of the Museum of
the California Academy of Sciences, San Francisco, California;
holotype (Fig. 6 of Hanna 1927b), no. 2031.
Comparison: This species closely resembles Pt. aculeifera by
possessing a branching process on the valve top, but can be easily identified from the latter by its conical rather than inflated
valve shape and its valve surface which lacks siliceous ridges.
Stratigraphic and geographic distributions: The occurrence reports of this species are few, however the oldest ones are reported from the late Cretaceous sediments in the Moreno Shale,
California (Hanna 1927b) and in West Siberia (Strelnikova
1974) (Text-figure 6). The youngest one is from the middle
Eocene core of IODP Expedition 302.
PLATE 5
Leptoscaphos levigatus (Sheshukova-Poretskaya) Suto, Jordan et Watanabe
Figures 1-18 are LM and figs. 19-28 are SEM. The scale bar in fig. 1 is 10µm and it also applies to figs. 2-18.
The scale bars in figs. 19-28 are 10µm.
1,2 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
3-5 IODP Site 302-2A-59X-2, 122-123cm. Valve view of
frustule.
6-8 IODP Site 302-4A-6X-2, 2-3cm. Valve view of
frustule.
9,10 IODP Site 302-2A-59X-2, 122-123cm.Valve view.
11,12 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
13,14. IODP Site 302-2A-59X-2, 122-123cm. Valve view.
15,16 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of frustule.
286
17,18 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
19 Enlargement of Fig. 20.
20 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of frustule.
21 IODP Site 302-2A-59X-2, 122-123cm. Inner valve
view.
22-24 Enlargement of Fig. 21.
25 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
26-28 Enlargement of Fig. 25.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 5
287
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Pterotheca harrensis (Fenner) Suto, Jordan et Watanabe comb.
nov.
Plate 8, figures 51, 52
Basionym: Pseudopyxilla harrensis FENNER 1994, p. 115, pl. 4, figs.
1-3.
Original description: The small valves are highly convex with a
basal incision. In this furrow, small oval depressions form a
basal circle. The two valves are connected by a hyaline,
structureless high mantle.
Type level and locality: Lower Eocene, the Fur Formation recovered from the Harre borehole.
Type specimen: Deposited in the collections of the Hustedt Collection, Bremerhaven; holotype (pl. 4, fig. 3 of Fenner (1994)),
sample K 134, 200.31 - 200.40m.
Comparison: This species differs in its shape from all other
Pterotheca species.
Stratigraphic and geographic distributions: This species was
reported from the early Eocene sediments of the Fur Formation,
Denmark (Text-figure 6). Only one specimen was observed in
the middle Eocene cores of IODP Leg 302-4A-4X-1, 0-3cm in
this study.
Remarks: The valve of this species is not cylindrical which
characterizes Pseudopyxilla, and lacks a single ring of puncta at
the base of its hypovalve which characterizes fossil Chaetoceros resting spore morpho-species. This species is characterized by its round valve shape and therefore Pseudopyxilla
harrensis is transferred to Pterotheca harrensis in this study.
Etymology: This species is named after the Harre borehole,
Denmark.
Pterotheca kittoniana Grunow in Van Heurck 1880-1885 var.
kittoniana
Pterotheca (Pyxilla ??) kittoniana Grunow in VAN HEURCK
1880-1885, pl. 83 bis., figs. 9-11.
Pterotheca kittoniana Grunow in Van Heurck – HARWOOD 1988, p.
86, figs. 18.1, 2. – FENNER 1991, p. 139, pl. 8, fig. 7. – FENNER
1994, p. 116, pl. 11, figs. 3-6.
Synonymy: Pyxilla ?? kittoniana Grunow in VAN HEURCK 1880-1885,
pl. 83, figs. 10, 11.
Pterotheca kittoniana (Grunow) GRUNOW – HOMANN 1991, p. 138,
pl. 53, figs. 19, 20, 26, 27.
Pterotheca kittoniana var. kamtschatica GAPONOV, PROSCHKINALAVRENKO 1949, p. 202, pl. 75, figs. 5a, b.
Pterotheca aculeifera GRUNOW, PROSCHKINA-LAVRENKO 1949,
p. 202, pl. 75, fig. 4a nec fig. 4b. – JOUSÉ 1963, figs. 111, 114. –
STRELNIKOVA 1974, p. 114, pl. 57, figs. 17-22 nec figs. 1-16,
23-26.
Description: Frustule heterovalvate, apical axis 6-32µm,
pervalvar axis of epivalve 8-30µm. In valve view, valve shape
circular. In girdle view, epivalve strongly convex or inflated
with coarse, strong siliceous ridges extending from the margin
to the apex as connecting spines, interspaces hyaline and with
one long central spine. Mantle of epivalve distinct and hyaline.
Hypovalve slightly convex and hyaline with one long central
spine and marginal spines. In valve view, spines rise from the
center and there are hyaline bifurcating ribs that radiate somewhat irregularly from the center towards the margin. Mantle of
hypovalve distinct and hyaline. Two frustules connected by siliceous ridges and central spines of each epivalve.
Type level and locality: Lower Eocene, Jutland, Denmark.
Type specimen: Depository not designated.
PLATE 6
Leptoscaphos punctatus (Grove et Sturt) Schrader
Figures 1-25 are LM and figs. 26-33 are SEM, respectively.
The scale bar in fig. 1 is 10µm and it also applies to figs. 2-25. The scale bars in figs. 26-33 are 10µm.
1,2 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
22,23 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
3,4 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
24,25 IODP Site 302-2A-54X-CC. Valve view.
5,6 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
7,8 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
9,10 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
11-13 IODP Site 302-4A-6X-2, 2-3cm. Valve view of
frustule.
14,15 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
16,17 IODP Site 302-2A-53X-CC. Valve view.
18,19 IODP Site 302-2A-53X-CC. Valve view.
20,21 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
288
26 IODP Site 302-2A-59X-2, 122-123cm. Valve view.
27,28 Enlargement of Fig. 26.
29 IODP Site 302-2A-59X-2, 122-123cm. Inner valve
view.
30,31 Enlargement of Fig. 29.
32 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of frustule.
33 Enlargement of Fig. 32.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 6
289
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Comparison: This species is very similar to Pt. aculeifera by
having siliceous ridges extending from the margin to the apex
but is distinguished by lacking huge spines with wing-like projections on the valve apex. This species is distinguished from
the variety Pt. kittoniana var. minuta Fenner by its larger size.
Stratigraphic and geographic distributions: This species has
been reported from Cretaceous sediments in western Siberia
(Strelnikova 1974), from Paleocene sediments in the Seymour
Island, Antarctic and from early Eocene deposits in Denmark,
but was not recognized in IODP Expedition 302 sediments in
this study (Text-figure 6).
Remarks: Pterotheca kittoniana (Grunow) Forti sensu Hajós
(1986, pl. 48, figs. 11-13), collected from the Miocene sediments of the Szurdokpüspöki diatomite stop in Hungary, belongs to Syndendrium akibae Suto because of its strongly
domed valve with several repeated, dichotomous, branching
hyaline processes (Suto 2003).
Fenner (1994) mentioned that epi- and hypovalves have been
assigned even to different genera Cladogramma Ehrenberg and
Pterotheca Grunow, because these two valves are so different
and the hypovalve possesses hyaline bifurcating ribs that radiate somewhat irregularly from the center towards the margin.
Therefore, Fenner (1994) also indicated that C. simplex Hajós
in Hajós and Stradner (1975, p. 928, pl. 4, figs. 7, 8, pl. 28, fig.
5) is a synonym of Pt. kittoniana. The genus Cladogramma was
erected by Ehrenberg (1854) and several species have been described such as C. californicum Ehrenberg (1854), C. conicum
Greville (1865), C. jordanii Hanna (1927b), C. morenoensis
Long, Fuge et Smith (1946), C. dubium Lohman (1948), C.
ellipticum Lohman (1948), C. pacificum Kolbe (1954) and C.
simplex Hajós in Hajós and Stradner (1975). All of these species
possess hyaline bifurcating ribs on their valve surface, but most
of them possess distinct mantles and vaulted valves except for
C. jordanii and C. simplex. Since the hypovalve of Pt.
kittoniana is nearly flat, Pt. kittoniana is separated from the genus Cladogramma. C. jordanii and C. simplex may belong to
the genus Pterotheca as mentioned by Fenner (1994), but it is
still not clear.
Etymology: This species is named in honor of Dr. F. Kitton.
Pterotheca kittoniana var. kamtschatica Gapanov 1927
Pterotheca kittoniana var. kamtschatica GAPANOV 1927 sensu
SHESHUKOVA-PORETSKAYA 1967, p. 268, pl. 39, figs 3a-f. –
GLEZER et al. 1974, pl. 47, figs. 9a-c.
Remarks: Pterotheca kittoniana var. kamtschatica Gaponov
sensu Proschkina-Lavrenko (1949, p. 202, pl. 75, figs. 5a, b)
and Fenner (1978, p. 527, pl. 9, figs. 2, 5), and Pt. kittoniana
Grunow sensu Jousé (1977, pl. 33, fig. 13) may belong to
Pterotheca reticulata because these specimens possess
anastomosing hyaline rims on their valve surface, but it is un-
PLATE 7
Porotheca danica (Grunow) Fenner
Figures 1-21 are LM and figs. 22-27 are SEM. The scale bar in figs. 1 and 2 is 10µm and it also applies to figs. 3-21.
The scale bars in figs. 22, 27 and 28 are 10µm and the scale bar in fig. 22 applies to figs. 23-26.
1,2 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
20,21 IODP Site 302-2A-59X-CC, 0-1cm. Valve view of
epivalve.
3,4 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
22 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
5,6 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
23 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
7-9 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
24 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
10,11 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
25 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
12,13 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
26 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
14,15 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve. T
27 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
16,17 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
28 IODP Site 302-2A-59X-CC, 0-1cm. Valve view of
epivalve.
18,19 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
epivalve.
290
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 7
291
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
known whether or not these specimens belong to Pt. reticulata
due to the difference of their stratigraphic ranges between the
holotype and typical Pt. reticulata (see Remarks on Pt.
reticulata). Moreover, this variety found by Baldauf and Barron
(1987, p. 7, pl. 10, fig. 14) in late Oligocene dredge samples
from the Navarine Basin Province, Bering Sea may be identical
with Pterotheca spp. or Syndendrium spp., but it is not yet clear
whether or not this specimen belongs to one of these genera.
Pterotheca kittoniana var. minuta Fenner 1994
Pterotheca kittoniana var. minuta FENNER 1994, p. 117, pl. 11, fig. 13.
Original description: The frustule is heterovalvar. One valve is
slightly convex. It has marginal spines and one long central
spine. The other valve has a high mantle with a basal incision
and four spines rising from the border between valve face and
mantle.
PLATE 8
Figures 1-19, 22-29, 32-48, 51 and 52 are LM and figs. 20, 21, 30, 31, 49 and 50 are SEM.
The scale bars in figs. 1 and 2, 32 and 33 are 10µm and it also applies to figs. 3-19 and 22-29, and 34-48.
The scale bars in figs. 20, 21, 30, 31, 49-52 are 10µm.
1-21. Pseudopyxilla dubia (Grunow) Forti
1-3 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
4,5 ODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
6,7 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
8,9 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
10,11 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
12,13 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
14,15 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
31 IODP Site 302-4A-5X-1, 2-3cm. Pseudopyxilla
jouseae ? or Porotheca danica ?. Girdle view of
epivalve.
32-50. Pterotheca evermanni Hanna
32,33 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
34,35 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
36 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
epivalve.
37,38 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of frustule.
39,40 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
16,17 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
41,42 IODP Site 302-2A-55X-CC. Girdle view of epivalve.
18,19 IODP Site 302-2A-57X-CC, 0-1cm. Girdle view of
epivalve.
43,44 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
20 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
45,46 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
21 Enlargement of Fig. 20.
47,48 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
22-31. Pseudopyxilla jouseae Hajós
22,23 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
epivalve.
49 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
24,25 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
epivalve.
50 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
26,27 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
51, 52. Pterotheca harrensis (Fenner) Suto, Jordan et Watanabe
51,52 IODP Site 302-4A-4X-1, 0-3cm. Girdle view.
28,29 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
292
30 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 8
293
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Type level and locality: Lowest Eocene, the Moler of Fur Formation, Denmark.
Type specimen: Deposited in the Grunow Collection in the
Naturhistorisches Museum, Wien. Slide no. NHW 3004 d.
Comparison: This variety differs from P. kittoniana var.
kittoniana by its smaller size and different shape (Fenner 1994).
Stratigraphic and geographic distributions: The holotype of
this variety is recognized from the earliest Eocene, but was not
observed in this study (Text-figure 6) therefore its stratigraphic
range and distribution are unknown.
Etymology: The Latin minuta means “small”
Pterotheca minuta (Fenner) Suto, Jordan et Watanabe comb. nov.
Plate 10, figures 1-30
Basionym: Pseudopyxilla minuta FENNER 1994, p. 115, pl. 4, figs. 5-7.
Synonymy: Hemiaulus kittonii Grunow in VAN HEURCK 1880-1885,
pl. 106, figs. 6-9 (6-8. spore in vegetative cell; 9. vegetative cell). –
CLEVE-EULER 1951, Handl. 2: 1, p. 123, figs. 266a-d (a. vegetative
cell; b. spore in vegetative cell; c, d: resting spores).
Pterotheca tuffata FENNER 1994, p. 117, pl. 4, figs. 11, 12.
Emended description: Frustule isovalvate, diameter 3-7µm,
transapical axis 5-14µm. Valves circular in valve view. Both
valves slightly convex in girdle view. Valve faces covered with
small knobs and short and long spines. Mantle of valve hyaline,
high and curved inward in its basal part.
Type level and locality: Lower Eocene, the Moler of Fur Formation, Denmark.
Type specimen: Deposited in the Grunow Collection in the
Naturhistorisches Museum, Wien. Slide NHW 3004 d.
PLATE 9
Figures 1-38 and 41, 42, 44-47 are LM and figs. 39, 40 and 43 are SEM, respectively.
The scale bar in figs. 1 and 2 is 10µm and it also applies to figs. 3-38, 41, 42, 46 and 47.
The scale bars in figs. 39, 40, 43, and 44 and 45 are 10µm.
1-40. Pterotheca aculeifera Grunow
1,2 IODP Site 302-4A-9X-CC. Girdle view of frustule.
3,4 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
5,6 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
frustule.
7,8 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
9,10 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
11,12 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
13,14 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
15,16 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
29,30 IODP Site 302-4A-8X-CC. Girdle view of frustule.
31,32 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
33,34 DSDP Leg 38, Site 338-26-5, 80-81cm. Girdle view
of epivalve.
35,36 DSDP Leg 38, Site 338-27-2, 50-51cm. Girdle view
of frustule.
37,38 DSDP Leg 38, Site 338-26-5, 80-81cm. Girdle view
of epivalve.
39 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
40 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view
of frustule.
17,18 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule.
41-43. Pterotheca aculeifera (Double spiny type)
41,42 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
epivalve.
19,20 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
43 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
21,22 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
44-47. Pterotheca aculeifera (Simple type)
44,45 DSDP Leg 38, Site 338-27-2, 50-51cm. Girdle view
of epivalve.
23,24 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
25,26 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
294
27,28 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
epivalve.
46,47 DSDP Leg 38, Site 338-27-2, 50-51cm. Girdle view
of epivalve.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 9
295
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Comparison: This species bears a close resemblance with the
fossil Chaetoceros resting spore morpho-genus Xanthiopyxis in
possessing numerous knobs and spines on its valve surface (see
Suto 2005e), but is distinguished from the latter by lacking a
single ring of puncta at the base of the hypovalve mantle.
Stratigraphic and geographic distributions: This species occurred in the early Eocene sediment of the Fur Formation, Denmark (Van Heurck 1880-1885, Fenner 1994) and in middle
Eocene cores from the central Arctic Ocean in this study
(Text-figure 6).
Remarks: The valve of this species is not cylindrical which
characterizes Pseudopyxilla, and lacks a single ring of puncta at
the base of its hypovalve which characterizes fossil Chaetoceros resting spore morpho-species. This species is characterized by its round valve shape and therefore Pseudopyxilla
minuta is transferred to Pterotheca minuta in this study.
Pterotheca tuffata Fenner (1994) is identical to Ps. minuta because the specimens had well-preserved long spines. Van
Heurck (1880-1885) also illustrated this resting spore with
well-preserved long spines on the valve surfaces in
Hemiaulus-like vegetative cells therefore this spore must possess short and long spines on the valve and so the genus
Pterotheca including this species may belong to the genus
Hemiaulus.
Etymology: The Latin minuta means “small”.
Pterotheca reticulata Sheshukova-Poretskaya 1967
Plate 10, figures 31-40
Pterotheca reticulata SHESHUKOVA-PORETSKAYA 1967, p. 229,
pl. 36, figs. 6a-c; pl. 8, figs. 4a-c. – SCHRADER and FENNER 1976,
p. 994, pl. 12, fig. 2 nec pl. 12, figs. 1, 11; pl. 38, figs. 10-12, 14-16; pl.
45, fig. 6. – DZINORIDZE et al. 1978, pl. 20, fig. 15. – HAJÓS 1986,
pl. 16, fig. 11; pl. 48, fig. 10.
PLATE 10
All figures are transmitted light micrographs (LM). Scale bar = 10µm, which applies to all figures.
1-30. Pseudopyxilla minuta Fenner
1,2 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
3,4 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
29,30 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule.
5,6 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
31-40. Pterotheca reticulata Sheshukova-Poretskaya
31,32 DSDP Leg 38, Site 338-8-1, 140-141cm. Girdle view
of epivalve.
7,8 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
33,34 DSDP Leg 38, Site 338-19-4, 10-11cm. Girdle view
of epivalve.
9,10 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
35,36 DSDP Leg 38, Site 338-21-1, 32-33cm. Girdle view
of epivalve.
11,12 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
37,38 DSDP Leg 38, Site 338-8-3, 10-11cm. Girdle view of
epivalve.
13,14 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule.
39,40 DSDP Leg 38, Site 338-9-1, 50-51cm. Girdle view of
epivalve.
15,16 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
41-44. Resting spore sp. A
41,42 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
frustule.
17,18 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
43,44 IODP Site 302-2A-53X-CC. Girdle view of frustule.
19,20 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule.
45-50. Resting spore sp. B
45,46 IODP Site 302-2A-54X-CC. Girdle view of frustule.
21,22 IODP Site 302-2A-54X-CC. Girdle view of frustule.
47,48 IODP Site 302-2A-54X-CC. Girdle view of frustule.
23,24 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
49,50 IODP Site 302-2A-54X-CC. Girdle view of frustule.
25,26 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
frustule.
296
27,28 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 10
297
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Description: Frustule heterovalvate, diameter 7-18µm,
transapical axis 18-30µm. In valve view, epivalve inflated and
cap-shaped, 7-18µm in height, neck developed with a height of
2-4µm. Hypovalve vaulted or cap-shaped or in the form of a
convex lid 3-5µm high with the same kind of neck as the
epivalve. Structure of both valves consists of anastomosing
ridges forming a well developed network on the mantle and
valve face. Neck hyaline or with fine striae, parallel to central
axis, 24-26 striae in 10µm. Around the valve face are quite long
and coarse processes, surrounded by a hyaline covering which
extends to the valve mantle.
Type level and locality: the upper Middle Miocene to lower Upper Miocene, Etolon suite sediments in the Rekinniki Bay, eastern side of Penzhina Bay, Kamchatka
Type specimen: Deposited in the collection of the Chair of
Lower Plants, St.-Petersburg University, St.-Petersburg, Russia, no. 1151-2.
Comparison: This species closely resembles Syndendrium
rugosum Suto in possessing long spines on its valve, but differs
from the latter by possessing a network of anastomosing ridges.
Stratigraphic and geographic distributions: The holotype was
collected from the late middle Miocene to early late Miocene
sediments from the Etolon suite in the Rekinniki Bay, eastern
side of Penzhina Bay, Kamchatka and was also found in late
Miocene to Pliocene sediments from the Maruyama suite along
the Nituy, Gurovka and Gornaya Rivers, South Sakhalin
(Sheshukova-Poretskaya 1967) (text-figure 6). The typical
specimens of Pt. reticulata occurred in the middle Miocene core
deposit of DSDP Site 348 (Schrader and Fenner 1976) and in
Miocene sediments of the Szurdokpüspöki diatomite stop in
Hungary (Hajós 1986). This species also occurred sporadically
in the latest Oligocene to middle Miocene sediments of DSDP
Leg 38, Site 338 in the Norwegian Sea, although it was not observed from IODP Leg 302.
Remarks: Specimens of Pterotheca reticulata found by
Schrader and Fenner (1976, p. 994, pl. 12, figs. 1, 11; pl. 38,
figs. 10-12, 14-16; pl. 45, fig. 6 nec pl. 12, fig. 2), Harwood
(1986, p. 86, pl. 6, figs. 20-23) and Scherer et al. (2000, p. 436,
pl. 5, figs. 4, 13) are identical to Syndendrium rugosum because
they possess the hyaline valve face with some wrinkles and no
anastomosing ridges, and with several repeated, dichotomous,
branching hyaline processes on the strongly convex or inflated
epivalve (Suto 2005c).
Specimens of Pterotheca kittoniana var. kamtschatica Gaponov
illustrated by Proschkina-Lavrenko and Sheshukova-Poretskaya (1967, p. 268, pl. 39, figs. 3a-f), Glezer et al. (1974, pl.
47, 9a-c) and Fenner (1978, p. 527, pl. 9, figs. 2, 5), Pt.
kittoniana in Jousé (1977, pl. 33, fig. 13) and Pt. sp. in Fenner
(1994, pl. 12, fig. 8) may belong to Pt. reticulata because of
their anastomosing ridges on the valve face, however they may
belong to other taxa because they possess some long spines on
the valve top. The holotype and typical specimens of Pt.
PLATE 11
Figures 1-35 are LM and figs. 36-38 are SEM, respectively.
The scale bar in figs. 1 and 2 is 10µm and it also applies to figs. 3-35. The scale bars in figs. 36-38 are 10µm.
1-38. Stephanogonia sp. A
1,2 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
3,4 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
5,6 IODP Site 302-2A-58X-CC. Girdle view of epivalve.
7,8 IODP Site 302-2A-58X-CC. Girdle view of epivalve.
9,10 IODP Site 302-2A-57X-CC. Girdle view of epivalve.
11,12 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
13,14 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
15,16 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
29,30 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
17,18 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
298
19-21 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
22-24 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
25,26 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
epivalve.
27,28 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
31,32 IODP Site 302-4A-6X-2, 2-3cm. Girdle view of
epivalve.
33-35 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
36 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of epivalve.
37 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
38 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
epivalve.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 11
299
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
reticulata occurred in Miocene deposits (see Text-figure 6)
however, the specimens shown here were all collected from
Eocene deposits. Therefore, they may be separate species.
with inflated plane, divided into 2 equal parts by 1 transverse internal septum. Mantle of epivalve distinct, slightly compressed
near the top of internal septum. Hypovalve nearly flat to slightly
convex in the center in girdle view.
Etymology: The Latin reticulata means “netlike”.
Plate 10, figures 41-44
Comparison: This species is similar to Anaulus arcticus in possessing transverse internal septa, but differs from it by having
only one septum.
Description: Frustule heterovalvate, apical axis 23-25µm,
pervalvar axis 8-10µm. Epivalve hyaline, vaulted in the center,
or undulated with five inflations in girdle view. Mantle of
epivalve hyaline. Hypovalve hyaline, undulated with five inflations in girdle view.
Stratigraphic and geographic distributions: Not reported from
fossil material. This species occurred rarely in middle Eocene
sediments from IODP Leg 302 Sites 2A and 4A in the central
Arctic Ocean.
Resting spore sp. A
Comparison: Not reported from fossil material.
Stratigraphic and geographic distributions: This species occurred rarely middle Eocene sediments from IODP Leg 302
Sites 2A and 4A in the central Arctic Ocean.
Remarks: This species was not observed in valve view in this
study.
Resting spore sp. B
Plate 10, figures 45-50
Description: Frustule heterovalvate. Valve square to rectangular in girdle view, apical axis 12-14µm, pervalvar axis
14-17µm. Epivalve hyaline, rectangular in girdle view, vaulted
Remarks: This species not observed in valve view in this study
however this species may be a variety of A. arcticus which possesses one septum because of the similarities in valve structures.
Resting spore sp. C
Plate 3, figures 1-23
Description: Frustule heterovalvate. Valve elliptical in valve
view, apical axis 13-35µm, transapical axis 5-15µm without
sheath. In girdle view, epivalve face vaulted, hyaline, surrounded by a sheath, with distinct mantle. Mantle of epivalve
hyaline. Sheath of epivalve ornamented with dense rows of simple pores. Hypovalve face slightly vaulted or nearly flat,
hyaline, with distinct mantle. Mantle of hypovalve hyaline.
PLATE 12
Figures 1-10, 14-31 and 33-35 are LM and figs. 11-13, 32 and 36 are SEM, respectively.
The scale bar in figs. 1 and 2, and 14 and 15 are 10µm and those also apply to figs. 3-10, and 16-31 and 33-35, respectively.
The scale bars in figs. 11-13 and 36, and 32 are 10µm and 5µm, respectively.
1-12. Stephanogonia sp. B
1,2 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of
epivalve.
3,4 IODP Site 302-4A-4X-1, 0-3cm. Girdle view of
epivalve.
5,6 IODP Site 302-2A-53X-CC. Valve view of epivalve.
7-10 IODP Site 302-2A-61X-2, 2-3cm. Valve view of
epivalve.
11
IODP Site 302-4A-5X-1, 2-3cm. Valve view of
epivalve.
20,21 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
22, 23. Trochosira spinosa Kitton
22,23 DSDP Leg 38, Site 338-14-3, 20-21cm. Girdle view
of chained frustules.
24, 25. Vallodiscus ? sp. A
24,25 IODP Site 302-2A-53X-CC. Valve view.
26-32. Xanthiopyxis type A (knobbly type)
26,27 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
28,29 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
12 IODP Site 302-4A-5X-1, 2-3cm. Oblique girdle view.
13-21. Trochosira coronata ? Schrader et Fenner
13 IODP Site 302-2A-59X-2, 122-123cm. Oblique valve
view.
14,15 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
16,17 IODP Site 302-2A-52X-2, 2-3cm. Valve view.
18,19 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
300
30,31 IODP Site 302-2A-52X-2, 2-3cm. Girdle view of
frustule.
32 IODP Site 302-4A-5X-1, 2-3cm. Oblique valve view.
33-36. Xanthiopyxis sp. B (short spiny type)
33-35 IODP Site 302-4A-5X-1, 2-3cm. Valve view.
36 IODP Site 302-4A-5X-1, 2-3cm. Girdle view of
frustule.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 12
301
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
Comparison: This taxon is characterized by its sheath around
the margin of the epivalve with dense rows of simple pores.
This taxon is very similar to Coronodiscus collarius Suto
(2004c) in possessing a sheath with dense rows of simple pores
but is distinguished from the latter by the absence of a single
ring of puncta and sheath on the hypovalve.
Stratigraphic and geographic distributions: This taxon occurred in middle Eocene sediments from IODP Leg 302 Sites
2A and 4A in the central Arctic Ocean.
Remarks: This taxon does not appear to belong to the fossil
resting spore morpho-genus Coronodiscus of extant
Chaetoceros because of the absence of a ring of puncta on the
hypovalve margin.
Resting spore sp. D
Plate 4, figures 1-39
Description: Frustule heterovalvate. Valve narrowly elliptical
in valve view, apical axis 6-18µm, transapical axis 4-12µm,
pervalvar axis 8-18µm without bristles. In girdle view, epivalve
vaulted with two humps, covered with numerous straight veins
and knobs, with distinct mantle. Mantle of epivalve distinct,
hyaline. Hypovalve vaulted in central area or nearly flat, with a
strong bristle near each apex, with distinct mantle. Mantle of
hypovalve hyaline with few scattered areolae.
Comparison: This taxon is characterized by having an epivalve
with two humps covered with numerous straight veins and
knobs, and a hypovalve with two strong bristles. This taxon is
very similar to the resting spore of extant Chaetoceros debilis
and fossil morpho-species genus Dispinodiscus species (Suto
2004b), but is clearly separated from them by its absence of a
ring of puncta on the hypovalve margin.
Stratigraphic and geographic distributions: This taxon occurred abundantly in middle Eocene sediments from IODP Leg
302 Sites 2A and 4A in the central Arctic Ocean.
Remarks: This taxon does not belong to the fossil resting spore
morpho-genus of Chaetoceros because of the absence of a ring
of puncta on the hypovalve margin. This taxon looks like
Hemiaulus tumidicornis (Strelnikova 1971, 1974), but differs
from the latter by its valve covered with knobs. Hemiaulus
tumidicornis sensu Barron (1985) and Dell’Agnese and Clark
(1994) from late Cretaceous sediments of the Alpha Ridge, central Arctic Ocean are also similar to this species due to the
pore-less valve surface, but resting spore sp. D is distinguished
from these specimens by its hypovalve with one hump. These
PLATE 13
Figures 1-33, 36-41 and 43-48 are LM and figs. 34, 35 and 42 are SEM.
The scale bar in figs. 1 and 2, and 36 and 37 are 10µm and those also apply to figs. 3-33 and 43-48, and 38-41.
The scale bars in figs. 34, 35 and 42 are 10µm.
1-35. Trochosira polychaeta (Strelnikova) Sims
1-3 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
4,5 IODP Site 302-2A-53X-CC. Valve view.
6,7 IODP Site 302-2A-53X-CC. Valve view.
8-10 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
11,12 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
13,14 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
15-17 IODP Site 302-2A-61X-2, 2-3cm. Valve view.
18,19 IODP Site 302-2A-59X-CC, 0-1cm. Valve view.
20,21 IODP Site 302-4A-4X-1, 0-3cm. Valve view.
22,23 IODP Site 302-2A-53X-CC. Valve view.
24,25 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
frustule.
302
32,33 IODP Site 302-2A-55X-CC, 0-1cm. Girdle view of
frustule connected to opposite valve.
34 IODP Site 302-2A-59X-2, 122-123cm. Girdle view
of connected valves.
35 IODP Site 302-2A-59X-2, 122-123cm. Oblique valve
view of frustule.
36-42. Chaetoceros hypovalve (hyaline type)
36,37 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
hypovalve.
38,39 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
hypovalve.
40,41 IODP Site 302-4A-7X-1, 2-3cm. Valve view of
hypovalve.
42 IODP Site 302-4A-5X-1, 2-3cm. Valve view of
hypovalve.
26,27 IODP Site 302-2A-61X-2, 2-3cm. Girdle view of connected valves.
43-48. Chaetoceros hypovalve (wrinkled type)
43,44 IODP Site 302-4A-8X-CC, bottom. Valve view of
hypovalve.
28,29 IODP Site 302-4A-7X-1, 2-3cm. Girdle view of
frustule.
45,46 IODP Site 302-4A-4X-1, 0-3cm. Valve view of
hypovalve.
30,31 IODP Site 302-2A-59X-CC, 0-1cm. Girdle view of
frustule.
47,48 IODP Site 302-4A-4X-1, 0-3cm. Valve view of
hypovalve.
Itsuki Suto, Richard W. Jordan and Mahito Watanabe
micropaleontology, vol. 55, nos. 2-3, 2009
Plate 13
303
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
specimens of Hemiaulus taxa may represent vegetative cells
and resting spores because of the similarities of their valve
shapes. Moreover, resting spore sp. D may be the descendant of
Hemiaulus tumidicornis sensu Barron (1985) and Dell’Agnese
and Clark (1994).
Stephanogonia sp. A
Plate 11, figures 1-38
Description: Valve truncated pyramidal with flat top, swollen
in the middle, and with a wide flat circular brim at the base,
turning up shortly at its edge, valve widest at the base, 12-14µm
in diameter. Valve surface covererd with numerous siliceous
ridges extending from the margin of valve and mantle to base of
valve top margin and running off to long bristles, interspace
hyaline with a row of puncta near the base of the ridge (see pl.
11, figs. 36-38). Mantle distinct with puncta equally spaced and
clearly separated (see Pl. 11, fig. 36). Frustule not observed.
Comparison: This taxon is very similar to Stephanogonia
hanzawae Kanaya (1959, p. 118, pl. 11, figs. 3-7) by its truncated pyramidal valve with flat top, but is distinguished from
the latter by its long and strong bristles on the valve top.
Stratigraphic and geographic distributions: This species occurred abundantly in middle Eocene sediments from IODP Leg
302 in the central Arctic Ocean.
Remarks: This taxon does not belong to the fossil resting spore
morpho-genus of Chaetoceros because of the absence of a ring
of puncta on the hypovalve margin and presence of numerous
areolae on the valve surface and the mantle (see Plate 11, fig.
36).
Stephanogonia sp. B
Plate 12, figures 1-12
Description: Frustule heterovalvate. In valve view, epivalve
circular, 13-38µm in diameter, covered with radial siliceous
ridges from the center to margin, interspace of ridges hyaline.
In girdle view, epivalve high to low cylindrical with vaulted
top, slightly swollen at the middle. Epivalve surface covered
with numerous siliceous ridges extending from the valve top to
base and some strong bristles running off from the ridges near
the vaulted area. Mantle of epivalve distinct with puncta
equally spaced and clearly separated (see Pl. 12, fig. 12). In
valve view, hypovalve circular and concave inside the frustule
(see Pl. 12, fig. 12) with sparsely concave areas. In girdle view,
hypovalve nearly flat.
Stratigraphic and geographic distributions: This species occurred abundantly in middle Eocene sediments from IODP Leg
302 in the central Arctic Ocean.
Trochosira coronata ? Schrader and Fenner 1976
Plate 11, figures 13-21
Trochosira coronata SCHRADER and FENNER 1976, p. 1003, pl. 29,
figs. 9-11; pl. 35, figs. 7-13, 20, 21. – SIMS 1988, p. 250, figs. 11-14,
27, 28. – FENNER 1994, p. 122.
Synonym: Trochosira mirabilis sensu DZINORIDZE et al. 1978, pl. 4,
fig. 14.
Emended description: See Sims (1988).
Type level and locality: Upper Eocene, DSDP Site
338-28-28-2, 48-50cm, the Norwegian Sea.
Type specimen: Depository not designated.
304
Comparison: This species differs from T. mirabilis by possessing three or four circular central spines.
Stratigraphic and geographic distributions: This species occurred in Eocene DSDP Sites 338-340 cores in the Norwegian
Sea (Schrader and Fenner 1976, Dzinoridze et al. 1978, Sims
1988) and from the Fur Formation in Denmark (Fenner 1994)
(Text-figure 7). The specimens considered to belong to this species occur in IODP Leg 302 sediments.
Remarks: The specimens from IODP Leg 302 in this study may
be dissolved valves of this species with eroded linking spines or
separation valves lacking linking spines of T. spinosa (and/or T.
polychaeta) as mentioned by Sims (1988). The specimen of
Trochosira coronata in Scherer and Koç (1996) is identified as
T. spinosa because it links by a ring of solid spines in the valve
central area.
Etymology: The Latin coronata means “crowned”.
Trochosira mirabilis Kitton 1871
Trochosira mirabilis KITTON 1871, p. 170, pl. 14, figs. 8, 9. – VAN
HEURCK 1880-1885, pl. 83 bis, fig. 13. – SCHMIDT 1874-1959, pl.
176, fig. 55; pl. 180, fig. 48. – CLEVE-EULER 1951, Handl. 2: 1, p.
110, fig. 234a. – SIMS 1988, p. 247, figs. 1-6, 25. – HOMANN 1991,
p. 65, pl. 44, figs. 5, 9-13. – FENNER 1994, p. 122, pl. 2, figs. 2-4.
Synonymy: Trochosira cf. mirabilis Kitton – HOMANN 1991, p. 66, pl.
44, figs. 7, 8.
Trochosira aff. mirabilis Kitton – FENNER 1991, p. 141, pl. 11, figs.
19, 20.
Emended description: See Sims (1988).
Type level and locality: Lower Eocene, Fur Formation, Denmark.
Type specimen: Depository not designated.
Comparison: This species is very similar to T. polychaeta as
they possess three-faceted rods on the valve center linking the
opposite valves, but this species is easily separated from the latter by its longer rod up to two times the length of each frustule
and by the presence of numerous long flattened spines at the
valve margin. This species is also distinguished from T.
coronata which is connected by several (2-5) circular central
linking spines (see Schrader and Fenner 1976, Sims 1988).
Stratigraphic and geographic distributions: This species occurred in Paleocene sediments of ODP Holes 698A, 700B and
702B in the sub-Antarctic southwest Atlantic Ocean (Fenner
1991), in early to middle Eocene Mors and Fur Formations,
Denmark (Kitton 1871, Van Heurck 1880-1885, Homann 1991,
Fenner 1994) and in late Eocene sediments from the eastern
slopes of the Ural Mountains (Sims 1988) (Text-figure 7).
Remarks: The occurrences of this species changed from the
Southwestern Atlantic Ocean in the Paleocene to the North Atlantic in the Eocene, but the cause of this migration from south
in the Paleocene to north in the Eocene is unknown.
Etymology: The Latin mirabilis means “curious”.
Trochosira polychaeta (Strelnikova) Sims 1988
Plate 13, figures 1-35
Trochosira polychaeta (Strelnikova) SIMS 1988, p. 251, figs. 15-21,
29-34.
Micropaleontology, vol. 55, nos. 2-3, 2009
Basionym: Sceletonema polychaetum STRELNIKOVA 1971, p. 42, pl.
1, figs. 3-5. – STRELNIKOVA 1974, p. 54, pl. 3, figs. 3-7. –
BARRON 1985, p. 141, pl. 10.1, figs. 2-4.
Synonymy: Pyrgodiscus triangulatus HAJÓS and STRADNER 1975, p.
928, figs. 11a, b; pl. 18, figs. 5, 6.
Trochosiropsis polychaeta (STRELNIKOVA) TAPIA in TAPIA and
HARWOOD 2002, p. 330, pl. 8, figs. 3, 4.
Comparison: This species differs from others by lacking marginal spines and by possessing numerous subcentral interdigitating spines.
Type level and locality: Upper Cretaceous (Campanian), Western Siberia.
Stratigraphic and geographic distributions: The occurrences
from Eocene to the Oligocene are reported from numerous areas, especially the North Atlantic Ocean (Text-figure 8). This
species also occurred in DSDP Site173 sediments, estimated to
be middle to late Miocene in age (Schrader 1973) and from the
middle Miocene Hawthorn Formation (Abbott and Andrews
1979).
Type specimen: Depository not designated.
Etymology: The Latin spinosa means “spiny”.
Emended description: See Sims (1988).
Comparison: This species is very similar to T. mirabilis as it
possesses three-faceted rods in the valve center linking the opposite valve, but this species is easily separated from the latter
by its shorter rod and by the absence of long flattened spines at
the valve margin.
Stratigraphic and geographic distributions: The occurrences of
this species in the late Cretaceous are reported from Western Siberia (Strelnikova 1971, 1974), Alpha Ridge in the Arctic
Ocean (Barron 1985, Sims 1988), Slidre Fjord and Horton
River Sections in Canada (Tapia and Harwood 2002) and
DSDP Site 275 in the South Pacific near New Zealand (Hajós
and Stradner 1975)(Text-figure 7). This study is the first to report its occurrence in the middle Eocene.
Remarks: On eroded valves, the central linking mechanism is
often missing, with little evidence to show that it had ever been
present, apart from a few missing cribra (see Plate 13, Figs. 4, 5,
22, 23, 35).
Etymology: The Latin poly-chaeta means “many bristles”.
Trochosira spinosa Kitton 1871
Plate 12, figures 22-23
Trochosira spinosa KITTON 1871, p. 170, pl. 14, figs. 6, 7. – VAN
HEURCK (1880-1885), pl. 83 bis, figs. 14, 15. – CLEVE-EULER
1951, Handl. 2: 1, p. 110, figs. 234b, c. – SHESHUKOVA-PORETSKAYA 1967, p. 137, pl. 11, figs. 6a, b; pl. 13, figs. 4a, b. –
SCHRADER 1973, p. 713, pl. 12, figs. 18, 19. – GLEZER et al. 1974,
pl. 31, figs. 5a, b; pl. 53, fig. 9. – SCHRADER and FENNER 1976, p.
1003, pl. 12, fig. 18. – DZINORIDZE et al. 1978, pl. 4, fig. 15. –
ABBOTT and ANDREWS 1979, p. 255, pl. 6, fig. 19. – HOMANN
1991, p. 67, pl. 17, figs. 6-13. – FENNER 1994, p. 123, pl. 3, fig. 9. –
SCHERER and KOÇ 1996, p. 89, pl. 4, figs. 18-20.
Trochosira spinosus Kitton sensu SIMS 1988, p. 248, figs. 7-10, 26. –
SCHERER et al. 2000, p. 440, pl. 2, figs. 4-6.
Trochosira spinosa ? Kitton sensu HARWOOD and BOHATY 2000, p.
94, pl. 4, fig. j.
Synonymy: Trochosira ornata GRUNOW in VAN HEURCK
(1880-1885), pl. 83, fig. 15. – FENNER 1994, p. 123, pl. 3, figs. 1, 2,
4.
Sceletonema ornatum Grunow sensu JOUSÉ 1955, p. 83, pl. 1, fig. 2.
Sceletonema spinosum (Kitton) JOUSÉ 1955, p. 85, pl. 1, figs. 3, 4.
Trochosira coronata Schrader and Fenner sensu SCHERER and KOÇ
1996, p. 89, pl. 4, figs. 22, 25.
Emended description: See Sims (1988).
Type level and locality: Lower Eocene. Mors, Jutland, Denmark.
Type specimen: Depository not designated.
Vallodiscus ? sp. A
Plate 12, figures 24, 25
Description: Frustule not observed. Valve elliptic in valve
view, apical axis 36µm, pervalvar axis 10µm. Valve hyaline,
convex, with a single ring of straight veins along the valve margin, extending normal to the plane of the valve. Center of
epivalve face hyaline.
Comparison: This species is similar to Vallodiscus species
(Suto 2005a) in possessing a single ring of straight veins along
the valve margin, but differs from other Vallodiscus species by
its elliptic valve shape.
Stratigraphic and geographic distributions: Only one specimen
was observed in middle Eocene sediments from IODP Leg 302
Site 2A-59X-2, 122-123 in the central Arctic Ocean in this
study.
Remarks: It is unknown whether or not this species belongs to
the fossil resting spore morpho-genus Vallodiscus of extant
Chaetoceros because its frustule was not observed and we could
not confirm the presence or absence of a single ring of puncta on
the hypovalve.
Xanthiopyxis type A (knobbly type) of Suto 2004e
Plate 12, figures 26-32
Description: Frustule heterovalvate. Valve oval to narrowly or
broadly elliptical in valve view. In girdle view, epivalve face
vaulted, with numerous knobs and short veins. Mantle of
epivalve hyaline. Hypovalve slightly vaulted or flat, or vaulted
in the center, hyaline or with knobs. Mantle of hypovalve
hyaline, with a single ring of puncta at its base.
Comparison: This taxon is characterized by knobs and veins on
the epivalve and the hyaline mantle of the epivalve.
Stratigraphic and geographic distributions: This taxon was observed rarely in middle Eocene sediments from IODP Leg 302
Sites 2A and 4A in the central Arctic Ocean in this study.
Remarks: The valves of these specimens belong to several
Xanthiopyxis species, but it is very difficult to determine which
one, when their frustules are not observed. Therefore, these
valves must be counted as “Xanthiopyxis type A (knobbly
type)”, when only an epivalve or hypovalve is observed during
the counting process (Suto 2004e).
Xanthiopyxis type B (short spiny type) of Suto 2004e
Plate 12, figures 33-36
Description: Frustule heterovalvate. Valve oval to narrowly or
broadly elliptical in valve view. In girdle view, epivalve face
305
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
vaulted, with numerous short strong spines. Mantle of epivalve
hyaline. Hypovalve slightly vaulted or flat, or vaulted in the
center, hyaline or with numerous strong spines. Mantle of
hypovalve hyaline, with a single ring of puncta at its base.
genera. Here, it is not possible to determine the nature of the
resting spores in Hemiaulus and/or Pyxilla, and the proposal
that Pterotheca represents such resting spores must be considered highly speculative.
Comparison: These specimens are characterized by short
strong spines.
At first, Costopyxis trochlea was introduced as a taxon in the
vegetative cell genus Trochosira (Hanna 1927b), but was then
moved to the resting spore genus Pterotheca (Fenner 1978) and
finally moved to Costopyxis (Glezer et al. 1988). Costopyxis
and Trochosira may be vegetative cells because their valves
possess numerous areolae, although their valves are heavily silicified. Anaulus arcticus looks like a resting spore because this
species possesses strong silicified valves and forms paired
valves as seen in Goniothecium and Gemellodiscus, but many
scattered pores cover the valve surface and a rimoportula occurs
at the valve center in SEM. Therefore it is not clear whether this
species may be a vegetative cell or resting spore. Leptoscaphos
levigatus may be the resting spore of L. punctatus or a related
species, because of the similarities in valve size and shape, and
possessing much fewer puncta on the valve surface. The taxonomic implications of Goniothecium and Odontotropis are indicated in Suto et al. (2008 and submitted), and these two genera
do not belong to Chaetoceros resting spores because their large
apical axis (2-3 times that of the largest Chaetoceros) are unlike
any known recent and fossil Chaetoceros spores.
Stratigraphic and geographic distributions: This taxon was observed rarely in middle Eocene sediments from IODP Leg 302
Sites 2A and 4A in the central Arctic Ocean in this study.
Remarks: These specimens occur abundantly in all of the cores
and onland sections studied. The valves of this taxon are those
of several Xanthiopyxis species, but these valves are difficult or
impossible to classify correctly when their frustules are not observed. Therefore these valves must be counted as
“Xanthiopyxis type B (short spiny type)”, when only the
epivalve or hypovalve is observed during the counting process
(Suto 2004e).
Hypovalves of fossil resting spores of Chaetoceros
Plate 13, figures 36-42 (hyaline type); Plate 13, figures 43-48
(wrinkled type)
Description: Hypovalve oval to narrowly or broadly elliptical
in valve view. In girdle view, valve face slightly vaulted or flat,
or vaulted in the center, hyaline or covered with numerous
knobs and short veins. Mantle hyaline. Mantle of hypovalve
hyaline, with a single ring of puncta at its base.
Remarks: The hypovalves of fossil resting spores of Chaetoceros can be separated into three types; hyaline, knobbly and
spiny types. The hyaline type hypovalve lacks processes. The
valve surface of the knobbly type one is covered with numerous
knobs and short spines. The spiny type is covered with lot of
short and long spines. It is impossible to identify which species
the hypovalve belongs to, because many species possess similar
hypovalves. Therefore we used these three types when isolated
hypovalves were preserved.
These three types may belong to Dispinodiscus ? sp. A,
Xanthiopyxis sp. A and sp. B., and perhaps to Liradiscus ? sp. A
and Vallodiscus ? sp. A if they are the fossil resting spores of
Chaetoceros.
DISCUSSION
The detailed stratigraphic data and paleoceanographic and
paleoecological implications of the Eocene Arctic Ocean were
presented by Stickley et al. (2008) for Holes 2A and 4A. In this
study, we present some strategic implications from the resting
spore taxonomic data and indicate the taxonomic problems of
some taxa.
Resting spore or vegetative cell?
It has been suggested that Pterotheca represents resting spores
of Pyxilla (e.g. Van Heurck 1896), but in terms of valve structure, circular cross-section and the tubed apex, there is a close
relationship to the spore of Rhizosolenia setigera Brightwell
(Hargraves 1976). Pterotheca species probably are the spores
of some extinct genus of the Centrales. They may be the spores
of species of the genus Hemiaulus Ehrenberg (Jousé 1963).
Gombos and Ciesielski (1983) also indicated that it is possible
that Pterotheca represents the resting spores of Pyxilla and this
speculation is based on the similarity in valve morphology of
the two genera, and the parallel stratigraphic range of the two
306
Stephanogonia sp. A and B may be resting spores, but their vegetative cells are unknown. Resting spore sp. C and sp. D,
Liradiscus ? sp. A, Peripteropsis ? sp. A and Vallodiscus ? sp. A
may not be Chaetoceros resting spores, because they lack a single ring of puncta on the hypovalve mantle. On the other hand,
Dispinodiscus ? sp. A, Xanthiopyxis type A and type B which
possess this character are fossil resting spores of Chaetoceros.
These resting spore taxa are not named in this study, because the
genera to which they belong are not yet clear so far. More detailed taxonomic data of these taxa from other oceans and ages
are needed for future taxonomic and biostratigraphic studies.
The possible changes of resting spore strategies before and
after the Eocene/Oligocene boundary
Forty-one diatom taxa including 30 taxa of fossil diatom resting
spores from Eocene Arctic sediments and 11 of their allied taxa
have been described in Suto et al. (2008 and submitted) and in
this study. Twenty-five out of these 30 taxa are resting spores,
while the remaining five taxa may be vegetative cells as indicated above. Text-figure 9 indicates the biostratigraphic ranges
of these species reported from the northern/southern Hemispheres and described in this study. Although their occurrence
data from the Paleocene are few, 10 resting spore species which
occurred in the ACEX samples had already appeared from the
late Cretaceous, while the others appeared in the Eocene. 21 out
of 25 (84%) resting spore taxa became extinct during the middle
Eocene to early Oligocene.
Suto (2006) indicated that a major event (named the EO Event)
that was characterized by the explosive diversification of
Chaetoceros resting spores at both the morpho-generic and specific levels, an increase in their abundance, and a decrease in
their valve size (from 40 to 20µm in average apical axis) occurred across the Eocene/Oligocene (EO) boundary in the Norwegian Sea. He also indicated that Chaetoceros might have
established itself as the main primary producer in the Oligocene
Norwegian Sea, replacing dinoflagellates and/or nannoplankton
which were the main producers till the late Eocene, because
their diversities decreased across the boundary (Falkowski et al.
Micropaleontology, vol. 55, nos. 2-3, 2009
2004). Suto (2006a) mentioned that the possible causes for the
decreased diversities of dinoflagellates and nannoplankton and
increased diversity of diatoms, especially Chaetoceros, were
associated with changes in coastal conditions from stable to unstable, associated with a regular seasonal environmental
change, such as depletion and sporadic supply of nutrients, to
which Chaetoceros resting spores might be adapted better than
dinoflagellate cysts.
Most taxa described in this study do not belong to Chaetoceros
because they lack a single ring of puncta on the hypovalve mantle that characterizes the resting spores of Chaetoceros, and became extinct before the Oligocene, therefore it is clear that
Chaetoceros did not flourish in the middle Eocene in the Arctic
Ocean. Other diatom genera that produced resting spores such
as Pterotheca and Pseudopyxilla, might have prospered before
the E/O boundary, although their vegetative cells are still unknown. Since some Chaetoceros resting spore taxa are recognized in this study, most coastal regions experienced a regular
seasonal environmental change, which benefited genera such as
Pterotheca, Pseudopyxilla and Odontotropis, but also there
might have been some patchy coastal upwelling regions with
nutrient depletion and sporadic supplies where Chaetoceros
could have survived and evolved. The abundant dinoflagellate
cysts preserved in the middle Eocene ACEX core (Moran et al.
2006) are evidence of the stable conditions before the E/O
boundary. When the abundance and species richness changes of
resting spores and dinoflagellate cysts in other cores across the
Eocene/Oligocene boundary are studied and it is shown that
resting spore taxa except Chaetoceros decreased contemporaneously with dinoflagellate cysts before the boundary, it will be
clarified that the resting spore ecology of most resting spore
taxa before the Eocene may have been similar to that of
dinoflagellate cysts rather than Chaetoceros resting spores after
the Oligocene, or there may be a southward “retreat” of calcareous microorganisms due to a prominent world-wide cooling
that occurred near the Eocene/Oligocene boundary.
Problems identifying Pterotheca, Pseudopyxilla and Porotheca
The distinction between fossil resting spore genera
Pseudopyxilla Forti, Pterotheca (Grunow) Forti and Porotheca
Fenner is currently vague.
The name Pseudopyxilla was introduced with a Latin description in Forti (1909). This name may have been provisional, and
therefore invalidly published (see ICBN 2000 Art. 34.1.b of
Greuter et al. 2000). Several species are also included in Forti’s
paper, but no generic type was designated. Since this genus was
erected, many species have been described including those
mentioned in this study such as Ps. aculeata Jousé, Ps.
americana (Ehrenberg) Forti, Ps. baltica Forti, Ps. capreolus
Forti and Ps. directa Pantocsek.
The name Pterotheca was first introduced by Grunow in Van
Heurck (1880-1885) (pl. 83, figs. 5, 6, 9-11), however the name
was also not validly published, as no description was provided
for the genus, although several species were described (P.
aculeifera, P. subulata, P. kittoniana and Stephanogonia
(Pterotheca?) danica). After this genus was introduced, Pt.
alata Strelnikova, Pt. clavata Strelnikova, Pt. costata Schibkova, Pt. cretacea Hajós et Stradner, Pt. infundibulum Krotov,
Pt. parvula (Hanna) Hajós et Stradner, Pt. pokroskajae Jousé,
Pt. reticulata Sheshukova-Poretskaya, Pt. sacculifera Fenner,
Pt. simplex Strelnikova, Pt. simplex Fenner, Pt. spada Tempère
TABLE 1
List of species that occurred in IODP Leg 302 sediments (*) and allied
species from other core materials.
*Anaulus articus Suto, Jordan et Watanabe sp. nov.
*Costopyxis trochlea (Hanna) Strelnikova in Glezer et al.
1988
*Dispinodiscus ? sp. A
*Goniothecium danicum Grunow in Cleve et Möller emend.
Suto in Suto, Jordan et Watanabe submitted
Goniothecium decoratum Brun
Goniothecium rogersii Ehrenberg
*Leptoscaphos levigatus (Sheshukova-Poretskaya) Suto, Jordan et Watanabe comb. nov.
*Leptoscaphos punctatus (Grove et Sturt) Schrader 1969
*Liradiscus ? sp. A
*Odontotropis sp. A
*Odontotropis sp. B
Odontotropis cristata Grunow 1884
*Odontotropis sp. C
*Odontotropis danicus Debes in Hustedt 1930
Odontotropis galeonis Hanna 1927b
*Odontotropis sp. C
*Odontotropis hyalina Witt 1886 (= Odontotropis klavsenii
Debes)
*Peripteropsis ? sp. A
*Porotheca danica (Grunow) Fenner 1994
Pseudopyxilla carinifera (Grunow in Van Heurck) Suto, Jordan et Watanabe comb. nov.
*Pseudopyxilla dubia (Grunow in Van Heurck) Forti 1909
*Pseudopyxilla jouseae Hajós in Hajós and Stradner 1975
*Pterotheca aculeifera Grunow in Van Heurck 1880 (=
Pterotheca crucifera Hanna 1927b)
*Pterotheca evermanii Hanna 1927b
*Pterotheca harrensis (Fenner) Suto, Jordan et Watanabe
comb. nov.
Pterotheca kittoniana Grunow in Van Heurck 1880-1885 var.
kittoniana
Pterotheca kittoniana var. kamtschatica Gapanov 1927
Pterotheca kittoniana var. minuta Fenner 1994
*Pterotheca minuta (Fenner) Suto, Jordan et Watanabe comb.
nov.
Pterotheca reticulata Sheshukova-Poretskaya 1967
*Resting spore sp. A
*Resting spore sp. B
*Resting spore sp. C
*Resting spore sp. D
*Stephanogonia sp. A
*Stephanogonia sp. B (Pterotheca sp. A)
*Trochosira coronata ? Schrader and Fenner 1976
Trochosira mirabilis Kitton 1871
*Trochosira polychaeta (Strelnikova) Sims 1988
Trochosira spinosa Kitton 1871
*Vallodiscus ? sp. A
*Xanthiopyxis type A (knobbly type) of Suto 2004e
*Xanthiopyxis type B (short spiny type) of Suto 2004e
*Hypovalve of fossil resting spore of Chaetoceros
307
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
et Brun, Pt. spinosa Jousé, Pt. subulata Grunow in Van Heurck,
Pt. trojana Harwood and Pt. uralica Jousé were added.
Later, Fenner (1994) separated the genus Porotheca from
Pterotheca danica because of its cylindrical valve with a central
elevation with a pore-like opening on top.
The fossil resting spore genus Pterotheca has been tabulated together with the genus Pseudopyxilla as mentioned above, because these have been no observations of their vegetative valves
as they usually dissolve in the sediments. The distinct differences between these genera have not been clarified from these
papers. Moreover, the vegetative cells of Pterotheca and
Pseudopyxilla are still unknown, therefore their generic names
must be regarded as morpho-genera for fossil resting spores according to Articles 3.3 and 3.4 of the International Code of Botanical Nomenclature (ICBN; Greuter et al. 2000), as with
fossil Chaetoceros resting spores (Suto 2003). We propose that
the differences between these two genera are a vaulted epivalve
in Pterotheca and a cylindrical one in Pseudopyxilla. As the result, Pterotheca minuta and Pt. harrensis are transferred from
Pseudopyxilla in this study. Moreover, Pterotheca carinifera
may belong to Pseudopyxilla or Porotheca because of its cylindrical valve, but it did not occur in this study and so the existence of the pore-like opening on top could not be clarified.
We redefine these three genera Porotheca, Pseudopyxilla and
Pterotheca as below.
Porotheca Fenner 1994
This genus is characterized by having a cylindrical to conical
valve and a central elevation with a pore-like opening on top. It
differs from Proboscia by the lack of a slit-shaped opening at
the top and from Rhizosolenia in that the apical rimoportula – if
present – has no external part. Species of this genus have resting
spores (Fenner 1994).
Pseudopyxilla Forti 1909
This genus is characterized by having a cylindrical to conical
valve. Frustule heterovalvate. Epivalve cylindrical to conical.
Epivalve surface hyaline or covered with numerous wrinkles or
strong and long process on the top, with no or few areolae.
Mantle of epivalve distinct, hyaline with no or numerous puncta
and areolae. Hypovalve convex or nearly flat. Hypovalve surface hyaline with no or few areolae. Mantle of hypovalve not
distinct, hyaline with no puncta and areolae.
Pterotheca (Grunow) Forti 1909
This genus is characterized by having a highly vaulted epivalve.
Epivalve surface hyaline, with no or few areolae, covered with
numerous strongly siliceous straight or anastomosing ridges,
and/or several spines. Mantle of epivalve distinct, hyaline with
no puncta and areolae. Hypovalve convex, less than the height
of the epivalve. Hypovalve surface hyaline or covered with numerous spines, with no or few areolae. Mantle of hypovalve
distinct, hyaline with no puncta and areolae.
ACKNOWLEDGMENTS
We thank the co-chief scientists Dr. Jan Backman (Stockholm
University) and Dr. Kathryn Moran (University of Rhode Island), and the scientific party of IODP Leg 302 ACEX as well
as the captain and crew who provided the opportunity for us to
sample the sediments on board R/V Oden. We wish to thank Dr.
Kota Katsuki (Kochi University), Dr. Nalân Koç and Dr.
Catherine E. Stickley (Norwegian Polar Institute) for invalu-
308
able discussions. Special thanks are given to Professor Kozo
Takahashi (Kyushu University) and Dr. Jonaotaro Onodera
(Kochi University) who provided sieved samples and gave numerous suggestions. We also thanks Dr. Andrey Yu. Gladenkov
(Geological Institute, Russian Academy of Sciences) and Mr.
Fumio Akiba (Diatom Minilab Akiba, Ltd.) for their invaluable
discussions and their careful pre-reviews. We also thank Dr.
Yoshihiro Tanimura (National Science Museum, Tokyo), who
kindly curated the type specimens described in this paper. This
research used samples and data provided by the Integrated
Ocean Drilling Program (IODP). IODP is sponsored by the U.S.
National Science Foundation (NSF) and participating countries
under the management of the Joint Oceanographic Institutions
(JOI) Inc.
REFERENCES
ABBOTT, W. H. and ANDREWS, G. W., 1979. Middle Miocene marine diatoms from the Hawthorn Formation within the Ridgeland
Trough, South Carolina and Georgia. Micropaleontology, 25:
225-271.
BACKMAN, J., MORAN, K., McINROY, D. B. et al., 2005a. IODP Expedition 302, Arctic Coring Expedition (ACEX): A first look at the
Cenozoic Paleoceanography of the central Arctic Ocean. Scientific
Drilling, 1: 12-17.
———, 2005b. Proceedings of the Integrated Ocean Drilling Program
302. College Station TX: Integrated Ocean Drilling Program Management International, Inc.
BALDAUF, J. G., 1985. Cenozoic diatom biostratigraphy and
paleoceanography of the Rockall Plateau region, North Atlantic,
Deep Sea Drilling Project Leg 81. In: Roberts, D. G., Schnitker, D. et
al., Initial Reports of the Deep Sea Drilling Project 81, 439-478.
Washington DC: US Government Printing Office.
BALDAUF, J. G. and BARRON, J. A., 1987. Oligocene marine diatoms
recovered in dredge samples from the Navarin Basin Province, Bering Sea. Washington, DC: U. S. Geological Survey. Bulletin 1765,
17 pp.
BARRON, J. A., 1975. Late Miocene-early Pliocene marine diatoms
from southern California. Paleontographica B, 151: 97-170.
———, 1985. Diatom biostratigraphy of the CESAR 6 core, Alpha
Ridge. In: Jackson, H. R., Mudie, P. J. and Blasco, S. M., Eds., Initial
Geological Report on Cesar: The Canadian Expedition to Study the
Alpha Ridge, Arctic Ocean, 137-148. Ottawa: Geological Survey of
Canada. Paper 84-22:
BARRON, J. A. and MAHOOD, A. D., 1993. Exceptionally well-preserved early Oligocene diatoms from glacial sediments of Prydz Bay,
East Antarctica. Micropaleontology, 39: 29-45.
BARRON, J. A., BUKRY, D. and POORE, R. Z., 1984. Correlation of
the middle Eocene Kellogg Shale of northern California.
Micropaleontology, 30: 138-170.
CLEVE-EULER, A., 1951. Die diatomeen von Schweden und Finnland.
Teil 1. Stockholm: Kungl. Svenska Vetenskapsalademiens.
Handlingar no. 2, 163 pp.
DELL’AGNESE, D. J. and CLARK, D. L., 1994. Siliceous microfossils
from the warm late Cretaceous and early Cenozoic Arctic Ocean.
Journal of Paleontology, 68: 31-47.
DESIKACHARY, T. V. and SREELATHA, P. M., 1989. Oamaru Diatoms. Berlin - Stuttgart,: J. Cramer - Gerbruder Borntraeger
Verlagsbuchhandlung. Bibliotheca Diatomologica, Band 19. 330 pp.
Micropaleontology, vol. 55, nos. 2-3, 2009
DZINORIDZE, R. N., JOUSÉ, A. P., KOROLEVA-GOLIKOVA, G.
S., KOZLOVA, G. E., NAGAEVA, G. S., PETRUSHEVSKAYA,
M. G. and STRELNIKOVA, N. I., 1978. Diatom and radiolarian Cenozoic stratigraphy, Norwegian Basin; DSDP LEG 38. In: Supko, P.
R., Perch-Nielsen, K. et al., Initial Reports of the Deep Sea Drilling
Project, supplements to volume 38, 39, 40 and 41, 289-385. Washington DC: US Government Printing Office.
ject 73: 495-511. Washington, DC: U.S. Government Printing
Office.
GOMBOS, A. M., JR. and CIESIELSKI, P. F., 1983. Late Eocene to
early Miocene diatoms from the southwest Atlantic. In: Ludwig, W.
J., Krasheninnikov, V. A. et al., Initial Reports of the Deep Sea Drilling Project, 71: 583-634. Washington, DC: U.S. Government Printing Office.
EHRENBERG, C. G., 1854. Mikrogeologie. Das Erden und felsen
schaffende Wirken des unsichtbar kleinen selbständigen Lebens auf
der Erde. Leipzig: Leopold Voss, 374 pp.
GRAN, H. H., 1912. Pelagic plant life. In: Murray, J. and Hjort, J., Eds.,
The Depths of the Ocean, 307-386. London: Macmillan and Co., Ltd.
FALKOWSKI, P. G., KATZ, M. E., KNOLL, A. H., QUIGG, A., RAVEN, J. A., SCHOFIELD, O. and TAYLOR, F. J. R., 2004. The evolution of modern eukaryotic phytoplankton. Science, 305: 354-360.
GREUTER, W., MCNEILL, J., BARRIE, R. et al., 2000. International
Code of Botanical Nomenclature (Saint Louis Code) adopted by the
Sixteenth International Botanical Congress, St. Louis, Missouri.
Regnum Vegetabile 138, 474 pp.
FENNER, J., 1978. Cenozoic diatom biostratigraphy of the equatorial
and Southern Atlantic Ocean. In: Supko, P. R., Perch-Nielsen, K. et
al., Initial Reports of the Deep Sea Drilling Project, supplement to
volume 38, 39, 40 and 41, 491-623. Washington DC: U.S Government Printing Office.
———, 1985. Late Cretaceous to Oligocene planktic diatoms. In: Bolli,
H.M., Saunders, J.B. and Perch-Nielsen, K., Eds., Plankton stratigraphy, 713-762. Cambridge: Cambridge University Press.
———, 1991. Taxonomy, stratigraphy, and paleoceanographic implications of Paleocene diatoms. In: Ciesielski, P. F., Kristoffersen, Y.
et al., Proceedings of the Ocean Drilling Program, Scientific Results
114, 123-154. College Station, TX: Ocean Drilling Program.
———, 1994. Diatoms of the Fur Formation, their taxonomy and
biostratigraphic interpretation. – Results from the Harre borehole,
Denmark. Aarhus Geoscience, 1: 99-163.
GREVILLE, R.K., 1865. Descriptions of new and rare diatoms, Series
XVII. Transactions of the Microscopical Society of London, New Series, 13: 97-105.
GROVE, E. and STURT, G., 1887. On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Part IV, appendix. Journal
of the Quekett Microscopical Club, series 2, 3: 131-148.
GRUNOW, A., 1866. Molèr aus Jütland eingesandt von Th. Jensen,
analisiert von A. Grunow. Hedwigia, 5: 145-146.
———, 1884. Die Diatomeen von Franz Josefs-Land. Kaiserliche
Akademie der Wissenschaften, Denkschriften, MathematischNaturwissen-schaftliche Classe, Vienna, 48: 53-112.
HAJÓS, M., 1968. Die Diatomeen der miozänen Ablagerungen des
Matravorlandes. Geologica Hungarica, 37: 1-401.
FORTI, A., 1909. Studi per una monografia del genere Pyxilla
(Diatomeae) e dei generi affini 20, XII, 1908. Nuova Notarisia, series 20, Padova, 24: 5-24.
———, 1976. Upper Eocene and lower Oligocene Diatomaceae,
Archaeomonadaceae, and Silicoflagellatae in Southwestern Pacific
sediments, DSDP Leg 29. In: Hollister, C. D., Craddock, C. et al., Initial Reports of the Deep Sea Drilling Project 35, 817-883. Washington, DC: U.S. Government Printing Office.
GAPANOV, Y. A., 1927. Isokopaemie diatomovie vodorosli p.o.
Kamchatki (Die fossilen Diatomeen der Halbinsel Kamschatka).
Materialy po geologiceskij i polesn. iskop. Daln. Vost., 49: 5-28,
Vladivostok.
———, 1986. Stratigraphy of Hungary’s Miocene diatomaceous earth
deposits. Geologica Hungarica, 49: 1-339.
GLADENKOV, A. Y., 1998 Oligocene and lower Miocene diatom
zonation in the North Pacific. Stratigraphy and Geological Correlation, 6: 150-163.
GLESER, S.I., JOUSÉ, A.P., MAKAROVA, I.V., PROSCHKINALAVRENKO, A.I. and SHESHUKOVA-PORETSKAYA, V.S.,
Eds., 1974. The diatoms of the USSR (fossil and recent), Vol. I: Leningrad: Publishing House “Nauka”, Leningrad Branch, 403 pp.
GLESER, S.I., MAKAROVA, I.V., MOISSEEVA, A.I. and
NIKOLAEV, V.A., Eds., 1988. The diatoms of the USSR (fossil and
recent), Vol. II, Fasc. 1: Leningrad: Publishing House “Nauka”, Leningrad Branch, 116 pp.
GOMBOS, A. M., JR., 1977. Paleogene and Neogene diatoms from the
Falkland Plateau and Malvinas Outer Basin. Leg 36, Deep Sea Drilling Project. In: Barker, P., Dalziel, I. W. D. et al., Initial Reports of
the Deep Sea Drilling Project, 36, 575-687. Washington, DC: U.S.
Government Printing Office.
———, 1983. Middle Eocene diatoms from the South Atlantic. In: Ludwig, W. J., Krasheninnikov, V. A. et al., Initial Reports of the Deep
Sea Drilling Project 71, 565-581. Washington, DC: U.S. Government Printing Office.
———, 1984. Late Paleocene diatoms in the Cape Basin. In: Hsu, K. J.,
LaBrecque, J. L. et al., Initial Reports of the Deep Sea Drilling Pro-
HAJÓS, M. and STRADNER, H., 1975. Late Cretaceous Archaeomonadaceae, Diatomaceae, and Silicoflagellatae from the South Pacific Ocean, Deep Sea Drilling Project, Leg 29, Site 275. In: Kennett,
J. P., Houtz, R. E. et al., Initial Reports of the Deep Sea Drilling Project 29, 913-1009. Washington, DC: U.S. Government Printing Office.
HANNA, G. D., 1927a. The lowest known Tertiary diatoms in California. Journal of Paleontology, 1: 103-126.
——— 1927b. Cretaceous diatoms from California. Occasional Papers
of the California Academy of Sciences, 13: 5-49.
———, 1970. Fossil diatoms from the Pribilof Islands, Bering Sea,
Alaska. Proceedings of the California Academy of Sciences, 37:
167-234.
HARGRAVES, P. E., 1976. Studies on marine plankton diatoms. II.
Resting spore morphology. Journal of Phycology, 12: 118-128.
———, 1984. The relationship of some fossil diatom genera to resting
spores. In: Richard, M., Ed., 8th Diatom Symposium, 1984, 67-80.
Koenigstein: Koeltz Scientific Books.
HARWOOD, D. M., 1988. Upper Cretaceous and lower Paleocene diatom and silicoflagellate biostratigraphy of Seymour Island, eastern
Antarctic Peninsula. In: Woodburne, M. O. and Feldmann, R. M.,
Eds., The Geology and paleontology of Seymour Island, 55-130.
Boulder, CO: Geological Society of America. Memoir 169.
309
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
HARWOOD, D. M. and BOHATY, S. M., 2000. Marine diatom assemblages from Eocene and younger erratics, McMurdo Sound,
Antarctica. In: Stilwell, J. D. and Feldmann, R. M., Eds.,
Paleobiology and paleoenvironments of Eocene rocks, McMurdo
Sound, East Antarctica, 73-98. Washington DC: American Geophysical Union. Antarctic Research Series, no. 76.
HARWOOD, D. M. and MARUYAMA, T., 1992. Middle Eocene to
Pleistocene diatom biostratigraphy of Southern Ocean sediments
from the Kerguelen Plateau, Leg 120. In: Wise, S.W.Jr., Schlich, R.
et al., Proceedings of the Ocean Drilling Program. Scientific Results
120, : 683-733. College Station, TX: Ocean Drilling Program.
HASEGAWA, Y., 1977. Late Miocene diatoms from the Nakayama
Formation in the Sado Island, Niigata Prefecture, Japan. Publications from the Sado Museum, 7: 77-101 (in Japanese with English abstract).
HOMANN, M., 1991. Die Diatomeen der Fur-Formation (Alttertiär)
aus dem Limfjord-Gebiet, Nordjütland/Dänemark. Geologisches
Jahrbuch, A: 1-170.
HUSTEDT, F., 1930. Die Kieselalgen Deutschlands, Österreichs und
der Schweiz. In: Rabenhorst, L., Ed., Kryptogamen-Flora von
Deutschland, Österreich und der Schweiz, Band VII, 1 Teil, 920 pp.
Reprint 1977, Koenigstein: Otto Koeltz Science Publishers.
———, 1955. Marine littoral diatoms of Beaufort, North Carolina. Marine Station Bulletin of Duke University, Durham, 6: 1-67.
JOUSÉ, A.P., 1951. Diatomeae et silicoflagellatae aetatis Cretae
Superne e Montibus Uralensibus Septentrionalibus. Botanicheskie
Materialy Otdela Sporovykh Rastenii, Botanicheskii Institute
Akademii Nauk SSSR, 7: 42-65.
———, 1955. Species novae diatomacearum aetatis Paleogenae.
Botanicheskie Materialy Otdela Sporovykh Rastenii, Botanicheskii
Institute Akademii Nauk SSSR, 10: 81-103.
———, 1963. Type Bacillariophyta. Diatom algae. In: V.A.
Vakhrameev, G.P. Radchenko and A.L. Takhtadzhan, Eds., The
foundations of paleontology. Guide for paleontologists and geologists of the USSR 14, 55-124. Moscow: Academy of Sciences Press .
———, Editor, 1977. Atlas of microorganisms in bottom sediments of
the oceans (diatoms, radiolarians, silicoflagellates, coccolits). Moscow: Publishing House “Nauka”, 196 pp. (in Russian).
KANAYA, T., 1957. Eocene diatom assemblages from the Kellogg and
“Sidney” Shales, Mt. Diablo area, California. Science Reports of the
Tohoku University, Second Series (Geology), 28: 27-124.
———, 1959. Miocene diatom assemblages from the Onnagawa Formation and their distribution in the correlative formation in Northeast Japan. Science Reports of the Tohoku University, Second Series
(Geology), 30: 1-130.
KATSUKI, K., SUTO, I., TAKAHASHI, K., ONODERA, J., JORDAN, R. W., STICKLEY, C. E. and KOÇ, N., submitted. The
Eocene paleoenvironment in the central Arctic Ocean based on the
IODP 302 M0004A diatom assemblages. Paleoceanography.
KITCHELL, J. A., CLARK, D. and GOMBOS, A. M., JR., 1986. Biological selectivity of extinction: A link between background and
mass extinction. Palaios, 1: 504-511.
KITTON, F., 1871. On diatomaceous deposits from Jutland. Journal of
the Quekett Microscopical Club, 2: 99-102, 168-171.
310
KOLBE, R. W., 1954. Diatoms from equatorial Pacific cores. Report of
the Swedish Deep-Sea Expedition. Göteborgs kugl. Vetenskaps-och
Vitterhets-Samhälle, 6: 1-49.
KUWATA, A., HAMA, T. and TAKAHASHI, M., 1993. Ecophysiological characterization of two life forms, resting spores and resting
cells, of a marine planktonic diatom, Chaetoceros pseudocurvisetus,
formed under nutrient depletion. Marine Ecology Progress Series,
102: 245-255.
LEE, Y.G., 1993. The marine diatom genus Chaetoceros Ehrenberg
flora and some resting spores of the Neogene Yeonil Group in the
Pohang Basin, Korea. Journal of Paleontological Society of Korea,
9: 24-52.
LEVENTER, A., 1991. Sediment trap diatom assemblages from the
northern Antarctic Peninsula region. Deep-Sea Research, 38:
1127-1143.
LOHMAN, K. E., 1948. Middle Miocene diatoms from the Hammond
Well: Cretaceous and Tertiary subsurface geology. Maryland Dept.
Geology, Mines, and Water Resources Bull., 2: 151-187.
LONG, J. A., FUGE, D. P. and SMITH, J., 1946. Diatoms of the Moreno
Shale. Journal of Paleontology, 20: 89-118.
MARINO, D., GIUFFRE, G., MONTRESOR, M. and ZINGONE, A.,
1991. An electron microscope investigation on Chaetoceros minimus
(Levander) comb. nov. and new obsevations on Chaetoceros
throndsenii (Marino, Montresor and Zingone) comb. nov. Diatom
Research, 6: 317-326.
MCCOLLUM, D. W., 1975. Diatom stratigraphy of the Southern Ocean.
In: Hayes, D. E., Frakes, L. A. et al., Initial Reports of the Deep Sea
Drilling Project 28, 515-571. Washington, DC: U.S. Government
Printing Office.
MCQUOID, M. R. and HOBSON, L. A., 1996. Diatom resting stages.
Journal of Phycology, 32: 889-902.
MEDLIN, L.M. and PRIDDLE, J., Eds., 1990. Polar marine diatoms.
Cambridge: British Antarctic Survey, 214 pp.
MORAN, K., BACKMAN, J., BRINKHUIS, H. et al., 2006. The Cenozoic palaeoenvironment of the Arctic Ocean. Nature, 441: 601-605.
NIKOLAEV, V. A., KOCIOLEK, J. P., FOURTANIER, E., BARRON,
J. A. and HARWOOD, D. M., 2001. Late Cretaceous diatoms
(Bacillariophyceae) from the Marca Shale Member of the Moreno
Formation, California. San Francisco: California Academy of Sciences. Occasional Papers, no. 152, 119 pp.
OKU, O. and KAMATANI, A., 1995. Resting spore formation and
phosphorus composition of the marine diatom Chaetoceros
pseudocurvisetus under various nutrient conditions. Marine Biology,
123: 393-399.
———, 1997. Resting spore formation of the marine planktonic diatom
Chaetoceros anastomosans induced by high salinity and nitrogen depletion. Marine Biology, 127: 515-520.
———, 1999. Resting spore formation and biochemical composition of
the marine planktonic diatom Chaetoceros pseudocurvicetus in culture: ecological significance of decreased nucleotide content and activation of the xanthophylls cycle by resting spore formation. Marine
Biology, 135: 425-436.
PANTOCSEK, J., 1903-1905. Beiträge zur Kenntnis der Fossilen
Bacillarien Ungarns. Berlin – Paszony. Volume 1 (1903), 77 pp;
Volume 2 (1903), 123 pp; Volume 3 (1905), 118 pp.
Micropaleontology, vol. 55, nos. 2-3, 2009
PROSHKINA-LAVRENKO, A. I., Ed., 1949. Diatom Analysis. Book 2.
Identifier of fossil and recent diatom algae. Orders Centrales and
Mediales. Leningrad: State Publishing House of Geological Literature, 444 pp. (in Russian).
ROSS, R. and SIMS, P.A., 1974. Observations on family and generic
limits in the centrales. Beihefte zur Nova Hedwigia, 45: 97-121, 7 pls.
SANFILIPPO, A. and FOURTANIER, E., 2003. Oligocene radiolarians, diatoms, and ebridians from the Great Australian Bight (ODP
Leg 182, Site 1128). In: Hine, A. C., Feary, D. A., Malone, M. J., et
al., Proceedings of the Ocean Drilling Program. Scientific Results
182, 1-24. College Station, TX: Ocean Drilling Program.
SCHERER, R. and KOÇ, N., 1996. Late Paleogene diatom
biostratigraphy and paleoenvironments of the northern Norwegian-Greenland Sea. In: Thiede, J., Myhre, A.M. et al., Proceedings
of the Ocean Drilling Program. Scientific Results 151, 75-99. College Station, TX: Ocean Drilling Program.
SCHERER, R. P., BOHATY, S. M. and HARWOOD, D.M., 2000.
Oligocene and lower Miocene siliceous microfossil biostratigraphy
of Cape Roberts Project Core CRP-2/2A, Victoria Land Basin,
Antarctica. Terra Antarctica, 7: 417-442.
SCHMIDT, A., 1874-1959. Atlas der Diatomaceen-Kunde. Begründet
von A. Schmidt, fortgesetzt von M. Schmidt, Fr. Fricke, O. Müller, H.
Heiden und F. Hustedt. 481 pls. Leipzig, Berlin: Aschersleben,
———, 1974. Diatoms of the Late Cretaceous (Western Siberia). Moscow, Publishing House “Nauka”, 203 pp. (in Russian)
SUTO, I., 2003. Taxonomy of the marine diatom resting spore genera
Dicladia Ehrenberg, Monocladia gen. nov. and Syndendrium
Ehrenberg and their stratigraphic significance in Miocene strata. Diatom Research, 18: 331-356.
———, 2004a. Taxonomy of the diatom resting spore form genus
Liradiscus Greville and its stratigraphic significance. Micropaleontology, 50: 59-79.
———, 2004b. Dispinodiscus gen. nov., a new diatom resting spore genus from the North Pacific and Norwegian Sea. Diatom (The Japanese Journal of Diatomology), 20: 79-94.
———, 2004c. Coronodiscus gen. nov., a new diatom resting spore genus from the North Pacific and Norwegian Sea. Diatom (The Japanese Journal of Diatomology), 20: 95-104.
———, 2004d. Fossil marine diatom resting spore morpho-genus
Gemellodiscus gen. nov. in the North Pacific and Norwegian Sea.
Paleontological Research, 8: 255-282.
———, 2004e. Fossil marine diatom resting spore morpho-genus
Xanthiopyxis Ehrenberg in the North Pacific and Norwegian Sea.
Paleontological Research, 8: 283-310.
SCHRADER, H. J., 1969. Die Pennaten Diatomeen aus dem Obereozan
von Oamaru, Neuseeland. Beihefte zur Nova Hedwigia, 28: 1-163.
———., 2005a. Vallodiscus gen. nov., a new fossil resting spore
morpho-genus related to the marine diatom genus Chaetoceros
(Bacillariophyceae). Phycological Research, 53: 11-29
———, 1973. Cenozoic diatoms from the Northeast Pacific, Leg 18. In:
Kulm, L. P., von Huene, R. et al., Initial Reports of the Deep Sea
Drilling Project 18, 673-797. Washington, DC: U.S. Government
Printing Office.
———, 2005b. Observations on the fossil resting spore morpho-genus
Peripteropsis gen. nov. of marine diatom genus Chaetoceros
(Bacillariophyceae). Phycologia, 44: 294-304.
———, 1978. Quaternary through Neogene history of the Black Sea,
deduced from the palaoecology of diatoms, silicoflagellates,
ebridians, and chrysomonads. In: Ross, D. A., Neprochnov, Y. P. et
al., Initial Reports of the Deep Sea Drilling Project 42(2): 789-901.
Washington, DC: U.S. Government Printing Office.
SCHRADER, H. J. and FENNER, J., 1976. Norwegian Sea Cenozoic
diatom biostratigraphy and taxonomy. In: Talwani, M., Udintsev, G.
et al., Initial Reports of the Deep Sea Drilling Project 38, 921-1099.
Washington, DC: U.S. Government Printing Office.
SHESHUKOVA-PORETSKAYA, V. S., 1967. Neogene diatom algae
of Sakhalin and Kamchatka. Leningrad: Leningrad University Press,
432 pp. (in Russian).
SIMS, P. A., 1988. The fossil genus Trochosira, its morphology, taxonomy and systematics. Diatom Research, 3: 245-257.
SIMS, P. A. and MAHOOD, A.D., 1998. Vulcanella hannae Sims &
Mahood, gen. et sp. nov., with a discussion of the genera Tumilopsis
Hendey, Acanthodiscus Pantocsek, Poretzkia Jousé and Goniothecium Ehrenberg. Diatom Research, 13:113-131.
STICKLEY, C.E., KOC, N., BRUMSACK, H.-J., JORDAN, R.W, and
SUTO, I., 2008. A siliceous microfossil view of middle Eocene Arctic paleoenvironments: a window of biosilica production and preservation. Paleoceanography, 23: PA1S14
doi:10.1029/2007PA001485.
STRELNIKOVA, N.I., 1971. Species novae bacillariophytorum e
sedimentis Cretae Posterioris in declivitate orientali partis polaris ac
praepolaris Montium Uralensium. Novitates Systematicae
Plantarum Non Vascularum, 8: 41-51. Leningrad: Publishing House
“Nauka”, Leningrad Branch.
———, 2005c. Taxonomy and biostratigraphy of the fossil marine diatom resting spore genera Dicladia Ehrenberg, Monocladia Suto and
Syndendrium Ehrenberg in the North Pacific and Norwegian Sea. Diatom Research 20: 351-374.
———, 2006a. The explosive diversification of the diatom genus
Chaetoceros across the Eocene/Oligocene and Oligocene/Miocene
boundaries in the Norwegian Sea. Marine Micropaleontology, 58:
259-269.
SUTO, I., JORDAN, R. W. and WATANABE, M., 2008. Taxonomy of
the fossil marine diatom resting spore genus Goniothecium
Ehrenberg and its allied species. Diatom Research, 23(2): 445-469.
SUTO, I., WATANABE, M. and JORDAN, R. W., submitted. Taxonomy of the fossil marine diatom resting spore genus Odontotropis
Grunow. Diatom Research.
TAPIA, P. M. and HARWOOD, D. M. 2002. Upper Cretaceous diatom
biostratigraphy of the Arctic archipelago and northern continental
margin, Canada. Micropaleontology, 48: 303-342.
TSOY, I. B., 2003. Eocene diatoms and silicoflagellates from the
Kronotskii Bay deposits (East Kamchatka). Stratigraphy and Geological Correlation, 11: 376-390.
VAN HEURCK, H., 1880-1885. Synopsis des Diatomées de Belgique.
Texte et Atlas. Anvers: H. Van Heurck, 235pp., 132 plates..
———, 1896. A Treatise on the Diatomaceae. Translated by W.E.
Baxter. London: William Wesley and Son, 558 pp.
WITT, O. N., 1886. Über den Polierschiefer von Archangelsk, Kurojedowo im Gouv. Simbirsk. Verhhandlungen, Russischßkaiserliche,
Mineralogische Gesellschaft zu St. Petersburg, Ser. II, 22: 137-177.
311
Itsuki Suto et al.: Taxonomy of middle Eocene diatom resting spores and their allied taxa from the central Arctic Basin
WORNARDT, W. W. JR., 1967. Miocene and Pliocene marine diatoms
from California. San Francisco: California Academy of Sciences.
Occasional Papers, no 63, 108 pp.
YANAGISAWA, Y. and AKIBA, F., 1998. Refined Neogene diatom
biostratigraphy for the northwest Pacific around Japan, with an intro-
312
duction of code numbers for selected diatom biohorizons. Journal of
the Geological Society of Japan, 104: 395-414.