Micropora Gray, 1848

Taylor, Paul D. & Villier, Loïc, 2022, Cretaceous microporid cheilostome bryozoans from the Campanian historical stratotype of southwest France, Geodiversitas 44 (18), pp. 515-525 : 517

Genus Micropora Gray, 1848

TYPE SPECIES. — Flustra coriacea Johnston, 1847 (non Esper, 1791), by monotypy; Recent, British Isles.

REMARKS

Gordon (1984) listed the key features of Micropora as its encrusting colony-form, raised lateral walls, granular cryptocyst that is minutely perforated and penetrated by opesiules close to the orifice, and basal pore chambers. Oral spines are rare, and ovicells are recumbent or immersed. In addition, the orifice is typically semielliptical in shape, and there is an avicularium located immediately distally of the orifice in most species.

Micropora is a speciose genus distributed pan-globally at the present-day. Bock (http://www.bryozoa.net/cheilostomata/ microporidae/micropora.html, accessed 5/7/2020) listed a total of 70 species living and fossil, including 16 species from the Cretaceous. According to Voigt (1981: p. 450) the genus is recorded as far back as the Early or Middle Cenomanian but this needs to be confirmed. Putative Cretaceous species of Micropora have not been adequately described or illustrated, and at least some are probably not congeneric with the type species.

None of the multitude of French Cretaceous bryozoans described by Alcide d’Orbigny were assigned by him to Micropora . A species originally assigned to Vincularia by d’Orbigny (1851: 78, pl. 657, figs 7-9) was later transferred to Micropora by Voigt (1968) but this species, M. transversa from the Maastrichtian of Cotentin, Manche, has an erect colony-form with narrow branches and would fall outside the definition of Micropora given by Gordon (1984) who restricted the genus to species that have encrusting colonies. Although Voigt’s illustrations (1968: pl. 7, figs 9-12) of this species comprise photographs of poorly preserved branches, there are clear similarities with Dimorphomicropora crestulata ( Ducasse, 1958) described below. The lectotype of M. transversa (MNHN.F.R61499) is also poorly preserved but is consistent with possible synonymy between this species and D. crestulata (see below).