docThe taxonomy and biology of crustose coralline algae
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The taxonomy and biology of crustose coralline algae
The taxonomy and biology of crustose coralline algae. Dr. Yvonne Chamberlain Institute of Marine Sciences University of Portsmouth © Y Chamberlain 2003 Crustose corallines are: Filamentous construction (multiaxial = many apical cells) Cell walls encrusted with calcium carbonate crystals. Successive filament cells joined by red algal pit connections which produce a capped body between cells. Adjacent filament cells can be secondarily joined by pit connections in some genera or simple cell fusion in others. Connections among cells Primary and secondary pit connections Cell fusions among adjacent filaments Crustose corallines have: Filaments are arranged in two ways: Dimerous in which the thallus has a single basal filament layer and a multicellular upper layer of erect filaments. Monomerous thallus with a many layered ventral system of filaments (medulla) and a multicellular upper layer (cortex). Terms for these types of construction have had many names, as detailed in prepared table (yellow page). Anatomical distinctions & growing points epithallial cells cortex Epithallial cells medulla Cortex Meristem Erect filaments Medulla Basal filament Dimerous thallus Monomerous thallus with coaxial arrangement Woelkerling ; Adey et al “Crustose” shapes Woelkerling et al. “Crustose” shapes Warty Encrusting Fruticose Lumpy Woelkerling et al. “Crustose” shapes Discoid Layered to foliose Entirely foliose Layered Woelkerling et al. Trichocytes (hair bearing cells) Loss of overlying cells Growth through overlying cells In older literature, these may be known as heterocysts or megacells Johansen Trichocytes Hydrolithon gardineri Hydrolithon onkodes Lee; Adey et al. Reproduction in Coralline algae Tetrasporangium Carposporophyte Apomictic Fertilization Gametophytes Conceptacles uniporate Sexual or tetrasporangial depending on genus. multiporate Always tetrasporangial Conceptacles Conceptacles Zonate tetrasporangia Hydrolithon H. onkodes Adey et al. 1982 Lithophyllum punctatum Uniporate conceptacles Adey et al. 1982 Titanoderma prototypum Uniporate conceptacles Adey et al. 1982 Mesophyllum erubescens Multiporate conceptacles Adey et al. 1982 Sporolithon ptychoides Individual compartments aggregated into sori cruciately divided Adey et al. 1982 Neogoniolithon clavacymosum Very small conceptacles Adey et al. 1982
