Tricephalopora saillans Canu & Bassler 1920, n. comb.
Creators: name: Martino, Emanuela Di
name: Rosso, Antonietta
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Bryozoa
Gymnolaemata
Cheilostomatida
Cribrilinidae
Tricephalopora
Tricephalopora saillans

description: Tricephalopora saillans (Canu & Bassler, 1920) n. comb.
(Fig. 34; Table 7)
Gephyrotes saillans Canu & Bassler 1920: 301 –302, pl. 5, figs. 18–20.
Material examined. Cotypes: USNM 63814 A– D, four specimens encrusting coralline algae, Danian (Paleocene), Alabama, USA. USNM 63814 C is chosen as lectotype.
Description. Colony encrusting, multiserial, unilaminar. Ancestrula and early astogeny not observed. Autozooids small, distinct, irregularly shaped, recalling a flying bee when viewed by light microscopy, longer than broad not including avicularia (mean L/W = 1.51). Frontal shield visible in a subcircular window, occupying less than half zooidal length, with 6, exceptionally 5 or 7, usually narrow (25–30 µm) irregularly spaced costae, the distalmost pair thicker (45–55 µm), lacking intercostal fusions. Costae converging and fused at zooidal midline along a narrow, elongated or rounded zone, adjacent costae separated by a single intercostal pore of variable size and shape; pelmatidia not observed in examined material. Primary orifice D-shaped to subcircular with slightly concave proximal margin, slightly broader than long (123 x 110 µm), hidden by raised peristome formed by band of smooth calcification derived from interzooidal kenozooids, leaving an arched lacuna between frontal shield and transversely elliptical secondary orifice. Avicularia adventitious, large, paired, resembling two lateral opened wings, each with swollen cystid, inclined and converging towards orifice, often contributing to formation of the distal rim; rostrum acutely triangular, more or less elongate, channelled and distomedially directed, with complete pivot bar. Ooecium subglobular, smooth, broader than long, immersed in distal zooid, opening deeply within peristome, barely visible in late ontogeny owing to secondary calcification spreading from kenozooids, and contributing to the formation of distal, arched peristomial rim together with avicularian rostra. Kenozooids responsible for swollen appearance of marginal portions of zooids, usually undefined, locally evident when broken.
Remarks. This species has been found encrusting coralline algae. Canu & Bassler (1920) assigned it to Gephyrotes, apparently because of the very salient peristome, although they do not describe the distal costae as bifurcated. They also reported the presence of a spiramen situated at the distal extremity of the costal field and discussed its potential function. A large arched lacuna is indeed present between the frontal shield and the secondary orifice but it is not a true spiramen. It is formed by the fusion of two wings of laminar calcification of kenozooidal origin. As observed by Taylor & McKinney (2006) in Tricephalopora lamellaria (Canu & Bassler, 1926), the above-mentioned characters and all other attributes of the species better conform to Tricephalopora. The two species have a generally similar aspect but differ in several features. Tricephalopora lamellaria (Fig. 35) has a very wide area of frontal shield exposed, the intercostal pores are very large and subquadrangular, there is a lessdeveloped kenozooidal network, avicularia differ in shape and position, and the lacuna between the frontal shield and the secondary orifice is filled by a band of calcification that leaves only two small circular pores. New SEM images of one of the cotypes of T. lamellaria (USNM69968 B) revealed the presence of a third adventitious avicularium, not described previously, placed distal to the orifice and directed proximally (Fig. 35).
Distribution. Paleocene (Danian) of Alabama, U.S.A.
N, Number of colonies and number of zooids measured; SD, standard deviation.
description: Published as part of Martino, Emanuela Di & Rosso, Antonietta, 2015, Revision of the bryozoan genus Gephyrotes Norman, 1903 (Cheilostomata, Cribrilinidae) with the description of two new taxa, pp. 261-283 in Zootaxa 3941 (2) on pages 275-276, DOI: 10.11646/zootaxa.3941.2.7, http://zenodo.org/record/253825