Ellipsoscapha sp.

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 : 107-108

Ellipsoscapha sp.

Fig. 4D .

1970 Cylichna discifera Koenen, 1885 ; Vonderbank 1970: 88, pl. 8: 7. 2016 Cylichnidae sp.; Hryniewicz et al. 2016: table 1, fig. 12I.

Material.— One specimen ( GPIBo 115 ) of the two mentioned by Vonderbank (1970), poorly preserved shell from the upper Paleocene , Basilika Formation , locality 500 m west of Trigonometric point 25, Hollendarbukta, Spitsbergen, Svalbard .

Measurements.— GPIBo 115: H, 7.0 mm; W, 4.4 mm.

Description. —Shell of small size, cylindrical, slightly widening abapically, apical opening relatively wide, depth obscured by remnants of following shell and/or sediment, protoconch not preserved. Shell layers peeled off in majority of specimen, but remnants display dense spiral ornamentation. Aperture adapically narrow, expanding in abapical direction. No trace of collumellar folds, callus, or umbilical slit; these features seem genuinely to have been absent.

Remarks.—The specimen in question was classified by Vonderbank (1970) as Cylichna discifera Koenen, 1885 , known from the Paleocene of Denmark ( Koenen 1885; Schnetler and Nielsen 2018); however, the latter species is much more elongate and equally wide over its entire height, being similar to true cylichnids. The specimen from Spitsbergen, in turn, possesses characters of Scaphandridae and in particular the genus Ellipsoscapha , known from the uppermost Cretaceous of the USA ( Sohl 1964), especially the shell widening adapically due to the expanding aperture, and the lack of a callus, columellar folds and an umbilical slit. Due to the imperfect preservation we refrain, however, from specific identification. Another Paleocene species of Ellipsoscapha , also in open nomenclature, has been reported from Greenland by Kollmann and Peel (1983). The latter species, however, is slimmer than the one from Spitsbergen and its last whorl reaches high above the apex.

Figures

Fig.4.Aporrhaid and scaphandrid gastropods from the upper Paleocene, Basilika Formation, locality 500 m west from Trigonometric point 25, Hollendarbukta (A, B, D) and Fossildalen (C), Spitsbergen, Svalbard. A, B. Aporrhais cf. gracilis Koenen, 1885, GPIBo 117 (A) and GPIBo 116 (B) in lateral (A1, B1) and apical (A2, B2) views.C.?Aporrhais cf.gracilis Koenen, 1885, identified by Hägg (1925) as Nassa sp., NRM-PZ Mo 149182 in apical (C1), lateral C2) and latero-apertural (C3) views. D. Ellipsoscapha sp. GPIBo 115 in apertural (D1), lateral (D2), apical (D3), and abapical (D4) views.