MICROPOROIDEA Gray, 1848

Taylor, Paul D., Martha, Silviu O. & Gordon, Dennis P., 2018, Synopsis of ‘ onychocellid’ cheilostome bryozoan genera, Journal of Natural History (J. Nat. Hist.) 52 (25 - 26), pp. 1657-1721 : 1661-1662

Superfamily MICROPOROIDEA Gray, 1848

Family ONYCHOCELLIDAE Jullien, 1882

Type genus

Onychocella Jullien, 1882 .

Diagnosis

Colony encrusting or erect frondose or palmate bifoliate or delicate to robust branching (vincularian), rarely free-living, not articulated, multiserial. Autozooids with extensive cryptocyst occupying half or more of the frontal area; gymnocyst absent or very narrow; opesia large, ovoidal, bell shaped or semi-elliptical, sometimes with opesiular indentations in the proximolateral corners; rarely a pair of separate, large opesiules; spines generally lacking, if present oral only, never circumopesial. Ovicells usually sunken and visible only as a slight convexity in the proximal cryptocyst of the distal zooid, sometimes hyperstomial with non-porous cryptocyst-like or gymnocystal ooecium. Avicularia present or absent, interzooidal or vicarious, often asymmetrical; pivotal bar uncalcified; mandible winged.

Remarks

Following a description of the critical type genus Onychocella , putative genera of Onychocellidae are treated in alphabetical order below. The generic diagnoses, all of which are revised, are based primarily on the characters of the type species. Unless otherwise stated, all morphological characters described were observed by us. The Remarks sections contain comments about differences in character states among other species that have been attributed to these genera.

Three genera – Virgocella Voigt, 1957 , Matyashegyella Zágoršek in Zágoršek and Kázmér, 2001 and Otiochmella Zágoršek, 2003 – placed in Onychocellidae by their original authors are here excluded from this family. Virgocella was introduced with Glauconome virgo von Hagenow, 1839 from the early Maastrichtian of Rügen, Mecklenburg-Vorpommern, Germany as the type species. Colonies are erect, vincularian, dichotomously branching and, according to Voigt, were possibly basally rooted; transversely fractured branches show a spoke-like radial arrangement of zooids. Poor surface preservation of available material hampers characterisation of zooidal morphology, but classification in Bryopastoridae d’ Hondt & Gordon, 1999 is more compelling than in Onychocellidae . Matyashegyella is monospecific for M. aubrechti Zágoršek , in Zágoršek and Kázmér 2001 from the Eocene (Priabonian) of Hungary. While the apparent presence of large ‘subvicarious’ avicularia prompted Zágoršek to assign his new genus to Onychocellidae , the squat zooids with rounded subrectangular opesiae invite comparison with Entomaria Duvergier, 1921 (e.g. Cheetham 1966; text-figs 25–27), which has been placed in Aspidostomatidae Jullien 1888 . Another monospecific Eocene (Priabonian) genus, Otiochmella , represented by the Austrian species O. discoida Zágoršek, 2003 , has free-living (lunulitiform) colonies resembling Otionella Canu and Bassler, 1917 and may be better assigned to Otionellidae Bock and Cook, 1998 or another lunulitid family. Steraechmella Lagaaij, 1952 , another genus usually associated with Onychocellidae but originally assigned by Lagaaij (1952) to Microporidae , has ovicells reminiscent of those in some species of Mollia Lamouroux, 1816 , and the genus also has some features in common with Rosseliana Jullien, 1888 and Gargantua Jullien, 1888 , which suggests that it is not an onychocellid.

Appendix 1 gives a key for the identification of onychocellid genera, which are revised below, based on the skeletal morphological characters of their type species.