A NEW SUBSPECIES OF SIX

A NEW SUBSPECIES OF SIX-LINED RACERUNNER,
CNEMIDOPHORUS SEXLINEATUS (SAURIA: TEIIDAE),
FROM SOUTHERN TEXAS
STANLEY
E.
TRAUTH
Department oj Biological Sciences. Arkansas State University,
State University, Arkansas 72467
AaSTRACT.-A new subspecies of the six-lined racerunner, Cnemidophorus sexlineatus, is
described from southern Texas. The new subspecies inhabits an inland sand dune plain and
a barrier island (Padre Island) along the Texas coast. A combination of small size,
distinctive striping pattern, and yellow head coloration distinguish this race from the prairie
racerunner (western subspecies), C. s. viridis, which occurs throughout much of Texas. Key
words: Cnemidophorus; new subspecies; racerunner; Texas.
Within the sexlineatus group of whiptail lizards (Duellman and
Zweifel, 1962), the six-lined racerunner (Cnemidophorus sexlineatus) is
the most wide-ranging species, occupying a diversity of arid to mesic
habitats in eastern and central North America (Conant and Collins,
1991). Two subspecies are recognized: an eastern race, C. s. sexlineatus, is
found throughout the lower eastern United States, and a western race, C.
s. viridis, is widespread in the central United States westward to the
Rocky Mountains. A narrow to broad zone of intergradation exists
between the two subspecies west of the Mississippi River from around St.
Louis, Missouri, southward through eastern Texas (Conant and Collins,
1991). During a six-year study (1974-1979) of the geographic variation in
external morphology of C. sexlineatus (Trauth, 1980), I examined a series
of museum specimens (more than 30 lizards) collected near Sarita,
Kenedy County and Falfurrias, Brooks County in the vertebrate
collections at Texas A&I University and Texas A&M University,
respectively, that revealed a previously undescribed race runner from
southern Texas. Although the coloration of these specimens had been
altered following preservation, both body size and striping pattern
differed markedly from the prairie racerunner (western subspecies), C. s.
viridis. Moreover, field work during the 1980s, which concentrated on
Kenedy and Brooks counties as well as other counties associated with the
South Texas or Rio Grande Plains (Tharp, 1952; Gould, 1962; Mahler,
1981) of extreme southern Texas (see Fig. I), showed that these
racerunners also possessed a striking yellow coloration on the face and
neck. Because this racerunner contrasts sharply with C. s. viridis in body
size, striping pattern, and head coloration, I describe herein a new race.
MATERIALS AND METHODS
Lizards were collected by hand or shot from five counties in extreme southern Texas (Fig.
I). Methods for determining meristic and morphometric data are provided elsewhere
438
THE TEXAS JOURNAL OF SCIENCE-VOL. 44, NO.4, 1992
FIGURE l. Distrubution of the Texas yellow-headed racerunner, Cnemidophorus sexlinealus
slephensi, in southern Texas. Solid circles represent collection sites. Starred circle
designates the holotype locality. County names are given (J. W. = Jim Wells). Enclosed
diagonal lines approximate the South Texas Plains.
(Trauth, 1980). Data on coloration were secured from live animals. Unless otherwise stated,
all specimens collected by the author are deposited in the Arkansas State University
Museum of Zoology (see Appendix).
RESULTS
Cnemidophorus sexlineatus stephensi, new subspecies
Holotype.-National Museum of Natural History (USNM 278270), an
adult male from 4.8 km. S Hebbronville, Jim Hogg Co., Texas, obtained
on 18 May 1983 by the author.
Paratypes.- Three males, five females (USNM 278271-78), same data
as holotype; five males, one female (USNM 278279-84), 8.9 km. N
Rachal, Brooks Co., Texas collected on II June 1981 by the author; two
females, University of Kansas Museum of Natural History (KU 208125­
26), 17.1 km. SW Hebbronville, Jim Hogg Co., Texas, collected on 18
May 1983 by the author; two females (KU 208127-28), collected 10.4 and
20 km. S Hebbronville, Jim Hogg Co., Texas, collected on 18 May 1983
by the author.
Diagnosis.-A subspecies of Cnemidophorus sexlineatus (Fig. 2)
characterized by a combination of features including small adult body
size with a maximum snout-vent length (SVL) of 68 mm (N = 106), the
absence of a vertebral stripe (although a vestige of a stripe may be
present on the nape or on the anterior region of the vertebral field, or
both, in some specimens), and yellow coloration on the face and lateral
surfaces of the neck in both adult and juvenile males and females. The
new race is a "true" six-lined racerunner with paired lateral, dorsolateral,
A NEW RACERUNNER FROM SOUTHERN TEXAS
439
FIGURE 2. Specimens and habitat of the Texas yellow-headed racerunner, Cnemidophorus
sex/ineatus stephensi. A. Adult female from paratype series (USNM 218211). B. Male
holotype (USNM 218210). C. Juvenile specimen from Kenedy County illustrating an
unusual convergence of paravertebral stripes (Texas A&I University collection, TAlC
2511-1). D. Sparsely vegetated white sand dune on the Mariposa Ranch near Falfurrias,
Brooks Co., Texas.
and paravertebral stripes when compared to C. s. viridis, which has, in
addition, a single or thin-divided vertebral stripe (Lowe, 1966); moreover,
C. s. sexlineatus, may exhibit a splitting of the vertebral stripe into two
or more additional stripes (Trauth, 1980).
Description of holotype.-An adult male (Fig. 2B) with a SVL of 65
mm; a tail length (TL) of 165 mm; 84 granules around body (GAB); 17/
17 femoral pores (FP); 29/30 subdigital lamellae on the fourth pes
(SOL); six granules between paravertebral stripes (PVG); 197 granules
from occiput to rump (GaR); 29/26 lateral supraocular granules (LSG);
9/9 circumorbital granules (COG); slightly enlarged postantebrachial
scales, and enlarged mesoptychial scales. No vertebral stripe;
paravertebral stripes merge just posterior to rump and then extend onto
anterior one fourth of tail; dorsolateral stripes extend onto tail; lateral
stripes blend into bright ventrolateral surface of tail. Dorsum of thighs
uniformly dark brown and bordered posteriorly by a straight light stripe;
vertebral field dark; paravertebral field light yellowish-green anterior to
forelimb, with light greenish suffusion onto midbody, then dark brown
posteriorly; dorsum of head a slate color; face (including superciliaries
and supralabials) and lateral surfaces of neck yellow; lateral surfaces of
belly light blue; chin, throat, and rest of belly and tail white.
Color in alcohol.-Dorsum of head, vertebral field, and greater portion
440
THE TEXAS JOURNAL OF SCIENCE-VOL. 44, NO.4, 1992
of paravertebral fields dark brown; yellow coloration on face and neck
replaced by a light blue; lateral surfaces of beJry retain a light blue
coloration. The rest of the belly, throat, and tail are white.
Variation in color and pattern.-The holotype and paratype series of
C. s. stephensi consist of 19 specimens; nine males and 10 females. There
are 13 adult specimens (SYL more than 55 mm); the other six are
juveniles (45-54 mm SYL). The tails average more than 2.5 times the
SYL. Adult females generally possess dark background fields, and the
yellow coloration of face and neck is less pronounced compared to males.
Adult males are generally smaller than adult females. A partial vertebral
stripe was present in 15 percent of these specimens. Juveniles exhibit the
general coloration of adult females.
Etymology.-The name stephensi was chosen as an expression of
gratitude to Hazel J. Stephens Hickey for her continuous financial
assistance toward the herpetological endeavors of the author.
DISCUSSION
Morphological comparisons.-Yariation in size and scutellation among
the three subspecies of C. sexlineatus are shown in Table I. Within
populations of C. s. stephensi, there was little overall variation in mean
scale counts by county, with the exception of specimens from Cameron
County (Padre Island). Also, little variation existed between the
combined mean values for C. s. stephensi and values for Texas intergrade
populations (c. s. sexlineatus/ viridis); however, maximum S YL
represents a major difference.
Unlike other subspecies of species within the genus Cnemidophorus
(see Zweifel, 1962; Walker, 1980, the western subspecies, C. s. viridis,
intergrades over a rather broad geographic area with the eastern
subspecies, C. s. sexlineatus; this is especially evident in eastern Texas
(Conant and Collins, 1991). In addition, a dramatic clinal trend in scale
counts, extending generally from northwest to southeast, exists within the
range of the species. The southeastern populations of C. s. sexlineatus
(for example, in Alabama and Georgia) tend to exhibit much higher
mean values for scutellation than do the western populations of C. s.
viridis (for example, in Oklahoma and Kansas). In C. s. stephensi, PYG
counts are generally lower than the other two subspecies or their
intergrades; this can be attributed to the more dorsal and medial
placement of the paravertebral stripes with a subsequent major reduction
or complete loss of the vertebral stripe (vestige in 48 percent of all C. s.
stephensl). Yellow coloration on the face and neck clearly distinguishes C.
s. stephensi from C. s. sexlineatus, C. s. viridis, and their intergrades.
Although males and sometimes females of C. s. viridis exhibit some
greenish-yellow pigmentation on the anterior background fields (on the
neck and shoulders), they never show this coloration extending onto the
TABLE I. Variation in morphological characters in the subspecies of Cnemidophorus sexlineatus. The mean and range values for C. s. sexlineatus, C.
s. viridis. and sexlineatus/viridis intergrades were taken from Trauth (1980). See text for abbreviations. Means are accompanied by ± one
standard error.
:>
Z
('Tl
~
:;lO
Subspecies
SVL"
TL"
GAB
FP
SDL
PVG
LSG
GaR
COG
Jim Hogg Co.
:;lO
66
166
(N= 21)
Brooks Co.
67
175
(N= 26)
Kenedy Co.
68
158
(N= 38)
Starr Co.
67
ISO
(N= 10)
Cameron Co.
:>
(j
('Tl
c. s. sltphensi
60
(N= II)
81.3 ± 1.1
30.7
± 0.5
c::
30.1 ± 0.4
7.0 ± 0.4
211.7 ± 2.8
21.4 ± 1.2
8.0 ± 0.5
(27-34)
(3-11)
(187-230)
(14-33)
(4-13)
21.1 ± 1.0
8.0 ± 0.4
(193-227)
(13-32)
(3-12)
8.4 ±0.3
205.3 ± 1.9
21.4 ± 0.9
6.4 ± 0.6
:;lO
(26-34)
(3-12)
( 172-229)
(14-28)
(3-10)
31.4 ± 0.6
8.3 ± 0.3
212.3 ± 45
24.0 ± 1.6
10.6 ± 1.2
::
(75-93)
(26-34)
82.6 ± 1.1
30.7 ± 0.4
30.6 ± 0.3
8.1 ±0.3
(69-95)
27·35)
(27-34)
(4-11)
82.3 ± 0.7
30.4 ± 0.4
29.2 ± 0.3
(76-91)
(25·35)
86.3 ± 1.9
32.2 ± 06
210.6
±
1.9
Z
Z
('Tl
:;lO
."
0
Vl
0
(79-93)
(30-37)
(28-34)
(5-13)
( 188-235)
(16-29)
(6-16)
87.0 ± 1.6
29.4 ± 0.6
30.6 ± 0.5
8.6 ± 0.5
220.7 ± 4.5
22.8 ± 1.1
6.4 ± 0.7
c::
...,
(82-99)
(26-33)
(27-33
(6-12)
(204-244)
(17-30)
(4-11)
.:I:
I'T'I
:;lO
Totals
68
180
83.0 ± 05
30.6 ± 02
30.1 ± 0.2
8.1 ± 0.2
210.2 ± 1.2
21.7 ± 0.4
7.5 ± 0.8
(69-99)
(25-37)
(26-34)
(3-16)
( 172-244)
( 13-33)
(3-16)
Z
...,
I'T'I
X
:>
c. s. se:clineolUsjviridis integrades
Tex.as
(N
Vl
78
177
= 246)
835 ± 04
30.5
± 0.2
27.8 ± 0.2
12.4 ± 0.2
208.4 ± 0.9
18.9±0.3
6.0 ± 0.2
(62-104)
(23-40)
(23-34)
(3-19)
( 168-224)
(11-32)
(2-12)
89.2 ± 0.4
32.0 ± 0.2
220.1 ± 0.8
27.6 ± 0.5
(25-40)
30.2 ± 0.1
(25-36)
145 ± 0.2
(74-104)
(9-20)
(186-263)
(12-47)
8.8 ± 0.2
(3-19)
90.7 ± 0.5
31.6 ± 0.2
28.4 ± 0.2
16.6 ± 0.2
219.2 ± 1.1
23.8 ± 0.7
7.7 ± 0.3
(75-104)
(26-37)
(20-32)
(12-23)
(189-247)
(12-43)
(3-16)
80.2 ± 0.4
30.8 ± 0.1
25.4 ±O.I
11.9 ± 0.1
197.1 ± 0.8
14.4 ± 0.2
3.9 ± 0.1
(69-96)
(20-36)
(21-30)
(6-19)
(169-227)
(8-34)
(1-10)
76.9 ± 0.3
31.0 ±O.I
24.8 ± 0.1
11.0 ± 0.1
190.3 ± 0.6
11.1 ± 0.2
3.4 ±O.I
(66-92)
(26-37)
(21-29)
(6-18)
(164-221)
(4-23)
(1-7)
C. s. sexlineatus
Alabama
(N
83
191
= 200)
Georgia
81
189
(N= 103)
C. $. viridis
Oklahoma
(N
Kansas
(N
81
179
= 250)
= 250)
'Maximum values.
79
146
.j:o
.j:o
442
THE TEXAS JOURNAL OF SCIENCE-VOL. 44, NO.4, 1992
face. Specimens from Kenedy County showed the most variation in neck
coloration; the presence of green to blue-green pigmentation, especially in
males, indicated some degree of genetic influence with C. s. viridis. In
contrast, specimens from Jim Hogg County showed the least amount of
color variation of the neck. Rarely did these lizards exhibit any color
other than yellow in the neck region. Because of the distinctive yellow
face in C. s. stephensi, an appropriate common name for this race is the
Texas yellow-faced racerunner.
Distributional ecology.-Cnemidophorus s. stephensi is distributed
throughout and along the fringe areas of the South Texas Plains and on
Padre Island (Fig. I). The eastern coastal region of this mesquite-live oak
savanna is characterized by moderately taB, white-to-brown colored sand
dunes (Fig. 20). In the western regions, the sand dunes are relative low
and have incorporated red clays. The lower Rio Grande Valley borders
the plains to the south, and a hilly "brush country" borders the plains to
the west and north. Within the South Texas Plains, C. s. stephensi was
occasionally taken syntopically with the Texas spotted whiptai~
(Cnemidophorus gularis gularis). Attempts to find C. s. stephensi
sympatrically with the Laredo striped whiptail (Cnemidophorus
laredoensis), a parthenogenetic clonal species complex (Walker, .987)
restricted to the Rio Grande Valley, have been unsuccessful. A zone of
intergradation between C. s. stephensi and C. s. viridis (to the north)
could not be established. Interestingly, C. s. stephensi occurs
sympatrically with another population of unusual yellow-headed lizards
in Kenedy County. Here, the presence of male southern prairie lizards
(Sceloporus undulatus consobrinus) that possess bright yellow on the side
of the head and on the ventral neck surfaces has been noted, but females
lack this yellow co~oration.
Natural history.- The type series of C. s. stephensi was collected by
excavation into a sandy, red clay roadcut. Numerous burrow systems
constructed by the lizards were scattered throughout this habitat; their
design was similar to those of the other subspecies of racerunners
(Trauth, 1983) and to burrows of C. laredoensis (Walker et aI., 1986;
Walker, 1987).
ACKNOWLEDGMENTS
I express my thanks to the following museum curators and curatorial technicians for their
assistance: G. R. Zug, R. 1. Crombie, and R. W. McDiarmid, National Museum of Natural
History; W. E. Duellman and J. T. Collins, University of Kansas Museum of Natural
History; J. R. Dixon, Texas A&M University; A. H. Chaney and S. J. White, Texas A&I
University, and F. W. Judd, Pan American University. Field assistance was provided by J.
M. Walker, J. M. Britton, J. E. Cordes, and P. J. Polechla. Department of Zoology,
University of Arkansas. A special thanks goes to R. G. Whistler, Chief Naturalist, Padre
Island National Seashore, and R. Fugate, Wildlife Specialist, Texas Parks and Wildlife
Department, who arranged access to public and private land, respectively. Specimens were
A NEW RACERUNNER FROM SOUTHERN TEXAS
443
collected under the authority of Texas Parks and Wildlife Department using Scientific
Permit no. 623. Portions of this study were completed while the author was a Visiting
Assistant Professor in the Department of Biology, Southern Methodist University.
LITERATURE CITED
Conant, R., and J. T. Collins. 1991. A field guide to reptiles and amphibians of eastern and
central North America. Houghton Mifflin, Boston, 450 pp.
Duellman, W. E., and R. G. Zweifel. 1962. A synopsis of the lizards of the sexlineatus
group (genus Cnemidophorus). Bull. Amer. Mus. Nat. Hist., 123:155-210.
Gould, F. W. 1962. Texas plants-a checklist and ecological summary. Texas Agric. Exp.
Sta., College Station, MP-585:1-121.
Lowe, C. H. 1966. The prairie lined racerunner. J. Arizona Acad. Sci., 4:44-45.
Mahler, W. F. 1981. Field studies on Texas endemics. Sida, 9: 176-181.
Tharp, B. C. 1952. Texas range grasses. Univ. Texas Press, Austin, xiv + 125 pp.
Trauth, S. E. 1980. Geographic variation and systematics of the lizard Cnemidophorus
sexlineatus (Linnaeus) in the United States. Unpublished Ph.D. Dissertation. Auburn
University, Auburn, Alabama, 201 pp.
- - . 1983. Nesting habitat and reproductive characteristics of the lizard Cnemidophorus
sexlinealUs (Lacertilia: Teiidae). Amer. Midland Nat., 109:289-299.
Walker, J. M. 1981. Systematics of Cnemidophorus gularis. II. Specific and subspecific
identity of the Zacatecas whiptail (Cnemidophorus gularis semiannulatus.) Copeia,
1981 :850-868.
1987. Distribution and habitat of the parthenogenetic whiptail lizard,
Cnemidophorus laredoensis (Sauria: Teiidae). Amer. Midland Nat., 117:319-332.
Walker, J. M., S. E. Trauth, J. M. Britton, and J. E. Cordes. 1986. Burrows of the
parthenogenetic whiptail lizard Cnemidophorus laredoensis (Teiidae) in Webb Co.,
Texas. Southwestern Nat., 31 :408-410.
Zweifel, R. G. 1962. Analysis of hybridization between two subspecies of the desert
whiptail, Cnemidophorus tigris. Copeia, 1962:749-766.
ApPENDIX
Available locality data for all specimens of Cnemidophorus sexlineatus stephensi
examined other than the type series are listed below and are plotted in Fig. 1. Brooks Co.:
19.6 km. W Falfurrias, Arkansas State University Museum of Zoology (ASUMZ) 9066;
19.2 km. SW Falfurrias, ASUMZ 9067, 9068; 6.4 km. S. Falfurrias, ASUMZ 9069, 9070;
19.2 km. SE Falfurrias, Texas A & M University and Texas Cooperative Wildlife Collection
(TCWC) 20882-20888. Cameron Co.: Louisiana State University collection (LSU) 33845,
33846; KU 12756, 12757; Padre Island, Frank W. Judd personal collection (FWJ) 46; South
Padre Island, FWJ 91, 165, 229, 230, ASUMZ 9102; Brazos Island, FWJ 204. Jim Hogg
Co.: 20 km. S Hebbronville, ASlJMZ 9071-9075; 0.5 km. N Agua Nueva, ASUMZ 9076,
9077; 1.9 km. S Agua Nueva, ASUMZ 9079-9081; 9.1 km. NW Hebbronville, ASUMZ
9081; 4.8 km. S Hebbronville, ASUMZ 9082-9084. Kenedy Co.: Sarita, ASUMZ 9095; 6.8
km. S Sarita, ASUMZ 9096; 16.8 km. S Mifflin, ASUMZ 9097-9102; 29.1 km S Sarita,
Texas A & I University (TAlC) 4786.0-4786.14, TAlC 2519.0-2519.5, TAlC 680,1770,4049,
3045; 7.1 km. S Sarita, University of Arizona (UAZ) 5602-5604. Starr Co.: 0.8 km. N La
Gloria, ASUMZ 9059-9061; 4.2 km. NE La Gloria, ASUMZ 9062-9065. Webb Co.: (no
data for specimens).