Tricephalopora levigata
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Ordo: Cheilostomatida
Familia: Cribrilinidae
Genus: Tricephalopora
Name
Tricephalopora levigata Canu & Bassler, 1920 – Wikispecies link – Pensoft Profile
- Tricephalopora levigata Martino, Emanuela Di, 2015, Zootaxa 3941: 276-277.
Materials Examined
Material examined.Cotypes:USNM63816 A–D, four specimens encrusting shells, Danian (Paleocene), Georgia, USA. Two of four specimens (C–D) are assigned to this species. USNM63816 C has been chosen as lectotype.
Description
Description. Colony encrusting, multiserial, unilaminar (Fig. 36). Ancestrula and early astogeny not observed. Autozooids small, distinct, with deep interzooidal furrows, irregularly shaped (Figs 37–38), recalling a flying bee when viewed by light microscopy, longer than broad not including avicularia (mean L/W = 1.58). Frontal shield visible in a subcircular window (Fig. 39), occupying less than half zooidal length, with 5–7 barely distinct, narrow (25–30 µm) costae lacking intercostal fusions. Costae converging and fused at zooidal midline, adjacent costae separated by a single intercostal pore of variable size and shape, mostly like a fissure; pelmatidia not observed in examined material. Primary orifice D-shaped to subcircular with slightly concave proximal margin, slightly broader than long (122 x 103 µm), hidden by raised peristome formed from band of smooth calcification derived from interzooidal kenozooids, leaving an arched, triangular lacuna between frontal shield and the secondary orifice (Figs 38–39). Secondary orifice semicircular. Adventitious avicularia, small, paired, oval, converging towards orifice, resembling laterally opened wings; rostrum rounded, distomedially directed, with complete pivot bar (Fig. 39) and small swollen cystid. Ooecium immersed in distal zooid, broader than long, proximally bordered by slightly prominent distal margin of orifice. Kenozooids responsible for calcification covering marginal portions of the zooids, usually undefined, locally evident when broken.
Discussion
Remarks. This species has been found encrusting molluscan shell. Tricephalopora levigata differs from T. saillans in having smaller zooids and avicularia. Canu & Bassler (1920) mentioned also the lack of a pivot bar as a further difference between these two species despite inking it on the figured specimens. Nevertheless, this feature is clearly visible in the SEM images. Two of four cotypes have a different aspect (see Fig. 40), as already noticed by Canu & Bassler (1920, pl. 6, figs 2–3). Nevertheless, the authors accommodated these specimens within the range of variability, mainly based on the measurements of avicularia and ovicells. In our opinion, observed differences, including the aspect of the frontal shield, are more relevant than the similarities, and we excluded them from the present species. Unfortunately, the poor preservation of the specimens prevents a complete description. The attribution of these specimens to the genus Tricephalopora is questionable.
Distribution
Distribution. Danian (Paleocene) of Georgia, U.S.A.
N (colonies, zooids)Mean SD Range Zooid length2, 10 422 41 376–484Zooid width2, 10 266 25 235–303Ovicell length2, 5 111 9 98–120Ovicell width2, 5 209 10 197–224Avicularia length2, 10 125 6 116–130Avicularia width2, 10 77 6 72–87Shield diameter2, 10 159 13 139–178
N, Number of colonies and number of zooids measured; SD, standard deviation.
Taxon Treatment
- Martino, Emanuela Di; Rosso, Antonietta; 2015: Revision of the bryozoan genus Gephyrotes Norman, 1903 (Cheilostomata, Cribrilinidae) with the description of two new taxa, Zootaxa 3941: 276-277. doi
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