Spiniflabellum, Martino, Emanuela Di & Rosso, Antonietta, 2015

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 (2), pp. 261-283 : 278

Genus Spiniflabellum n. gen.

Diagnosis. Colony encrusting, unilaminar, multiserial, forming patches. Autozooids elongate, elliptical. Frontal shield lacking a gymnocyst, formed by numerous narrow costae separated by many minute intercostal pores and bearing frontally projecting, tubular pelmatidia. Avicularia of one type, adventitious and paired. Primary orifice obscured by a broad, robust pair of bifurcations of the distalmost costae that fuse in the midline forming a spiramen-like opening. Numerous, coalescent, hollow spines aligned in a gently convex arch distal to the orifice to form a flabellate structure.

Type species. Gephyrotes spinosa Canu & Bassler, 1928 .

Etymology. Latin spina, spine, and flabellum (n.), fan, alluding to the flabellate, coalescent spines overarching the orifice.

Remarks. This monospecific genus is introduced here to accommodate Gephyrotes spinosum Canu & Bassler 1928 . They defined G. spinosum as a distinctive species having a very different costate shield from that of the type species G. nitidopunctatus and more closely related to that of Acanthocella Canu & Bassler, 1917 , junior synonym of Corbulipora MacGillivray, 1895 . The new genus and the encrusting phase of Corbulipora effectively share the general spinous appearance of the frontal shield essentially owing to the tubular, prominent pelmatidia on the costae, but differ in several other features. Corbulipora is a multiphased genus with large, interzooidal avicularia, and hyperstomial, globular ovicells with a median suture and two frontal fenestrae exposing the endooecium, whereas the new genus Spiniflabellum is exclusively encrusting, lacks interzooidal avicularia possessing instead the adventitious type, and apparently has no ovicells. A further difference is related to the development of the pair of costae most proximal to the orifice. In Spiniflabellum the distalmost pair of costae bifurcates, projects into the orifice and fuses, hiding the primary orifice, forming the distal margin of the secondary orifice and terminating the frontal. In some species of Corbulipora the pair of costae most proximal to the orifice are robust and prominent, forming a raised mucro or, if associated to the ovicell, a bridge-like structure.

Cribrilina Gray, 1848 , Collarina Jullien, 1886 , and Reginelloides Soule, Soule & Chaney, 1995 , are similar to Spiniflabellum in having robust suboral costae and latero-oral adventitious avicularia. In addition, Reginelloides has a variable number of distal flabellate spines. Spiniflabellum , however, has tubular pelmatidia, lacking in all of the above-mentioned genera, which also have obvious ooecia.

Distribution: Recent of north of Cuba and Straits of Florida ( Fig. 1 ).

Figures

FIGURE 1. Map showing the spatial and temporal distribution of all the studied species. 1, Gephyrotes nitidopunctatus (Smitt, 1868); 2, Gephyrotes fortunensis Pouyet, 2000; 3, Gephyrotes moissettei n. sp.; 4, Gephyrotes spectabilis Canu & Bassler, 1920; 5, Gephyrotes quadriserialis Canu & Bassler, 1920; 6, Gephyrotes convexus Canu & Bassler, 1920; 7, Tricephalopora saillans (Canu & Bassler, 1920); 8, Tricephalopora levigata (Canu & Bassler, 1920); 9, Spiniflabellum spinosum Canu & Bassler, 1928. Open circles, Recent; solid circles, Miocene; diamond, Oligocene; stars, Eocene; triangles, Danian.