Onychocellaria Voigt, 1957

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 : 1692-1693

Genus Onychocellaria Voigt, 1957

( Figure 21 )

Type species

Eschara rhombea von Hagenow, 1851 , by original designation. Cretaceous, Maastrichtian, Maastricht, Netherlands.

Diagnosis

Colony erect bifoliate, palmate ( Figure 21 (a)), unbranched, tapering proximally and presumably with basal rootlets. Autozooids diamond shaped; zooidal boundaries sharply raised. Cryptocyst extensive, granular. Gymnocyst lacking. Opesia subterminal, occupying about one-third of frontal surface; semielliptical, wider than long, the proximal edge gently convex, opesiular indentations present; lacking lateral constrictions. Ovicells immersed, visible as a small cap on the distal margin of the fertile zooid ( Figure 21 (b)). Avicularia vicarious, symmetrical, large, about 1.5× longer than an autozooid but of similar width; opesia semielliptical with a long medioproximal sinus ( Figure 21 (b)); rostrum long, parallel-sided, distal end rounded arch shaped.

Remarks

Aside from the type species, Voigt (1957) also assigned to his new genus Onychocella linearis Levinsen, 1925 from the Maastrichtian of Denmark and Germany, and subsequently ( Voigt 1968), Eschara caecilia d’ Orbigny, 1851 from the Maastrichtian of Cotentin, Normandy, France. Unlike the type species, O. caecilia has cylindrical branches and may have been truly cellariiform (i.e. multiply articulated) rather than just basally jointed, and questionably assignable to Onychocellidae . The key characters of Onychocellaria are thus the large, symmetrical avicularia and evidence for basal articulation.

Range

Cretaceous (Campanian to Maastrichtian).

Figures

Figure 21. Onychocellaria rhombea (von Hagenow); Late Cretaceous, Maastrichtian, Curfs Quarry, near Berg, Maastricht, Limburg, Netherlands; neotype of Voigt (1957), RBINS 9554; (a) palmate branch; (b) autozooids, some ovicellate, and two avicularia. Images courtesy of Kamil ZágorŠek. Scale bars: a = 1 mm; b = 500 µm.