Inoperna Conrad, 1875

Hryniewicz, Krzysztof, Amano, Kazutaka, Bitner, Maria Aleksandra, Hagström, Jonas, Kiel, Steffen, Klompmaker, Adiël A., Mörs, Thomas, Robins, Cristina M. & Kaim, Andrzej, 2019, A late Paleocene fauna from shallow-water chemosynthesis-based ecosystems, Spitsbergen, Svalbard, Acta Palaeontologica Polonica 64 (1), pp. 101-141 : 114

Genus Inoperna Conrad, 1875

Type species: Inoperna carolinensis Conrad, 1875 ; Campanian– Maastrichtian , Upper Cretaceous, southeastern USA .

Remarks.— Inoperna Conrad, 1875 , is a poorly known mytilid bivalve genus reported from Mesozoic shallow-water deposits (e.g., Woods 1900; Stephenson 1923; Wade 1926; Cox and Arkell 1948; Hautmann 2001). Specimens assigned to Inoperna are elongate, thin-shelled mytiliform bivalves with subterminal umbones and characteristic ornament of commarginal corrugations, some of which merge into bundles of dorsal commarginal folds. Ten species, including Inoperna plenicostata ( Anderson, 1970) discussed herein, have been recorded previously ( Stenzel et al. 1957: 74; Vonderbank 1970). Mauricia Harris, 1919, from the middle Eocene Cook Mountain Formation (Claiborne Group) in Texas, USA, is similar to Inoperna with respect to shell shape and ornament and could represent the same lineage ( Stenzel et al. 1957).