Semieschara d’ Orbigny, 1852

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 : 1701

Genus Semieschara d’ Orbigny, 1852

( Figure 28 )

Type species

Semieschara flabellata d’ Orbigny, 1852 , by subsequent designation ( Canu and Bassler 1929, p. 52). Turonian, Sainte-Maure-de-Touraine, Indre-et Loire, France .

Diagnosis

Colony unilamellar ( Figure 28 (a)). Autozooids subhexagonal; zooidal boundaries raised. Cryptocyst extensive, granular. Gymnocyst lacking. Opesia terminal, occupying about half frontal surface; bell shaped, lacking opesiular indentations and constrictions. Ovicells unknown. Avicularia vicarious, asymmetrical ( Figure 28 (b)), slightly smaller than an autozooid; opesia longitudinally elliptical; rostrum curved, acutely triangular.

Remarks

Since its proposal, Semieschara has occasionally been used as a form genus for erect unilamellar colonies differing significantly in zooidal morphology (e.g. Canu and Bassler 1929). Gordon and Taylor (1999, p. 25) regarded Semieschara as a synonym of Onychocella , a view upheld by Zágoršek (2003, p. 139) who noted that although it has priority over Onychocella , the name Semieschara has been used so seldom that it would not serve taxonomic stability to favour it over Onychocella . We follow these authors in treating Semieschara as a redundant synonym of Onychocella .

Figures

Figure 28. Semieschara flabellata d’Orbigny; syntype, MNHN F.A24644; Cretaceous, Turonian, Sainte- Maure-de-Touraine, Indre-et Loire, France; (a) fragmentary colony; (b) autozooids and an avicularium (centre right). Scale bars: a = 1 mm; b = 200 µm.