Abyssomelania, Kaim, Jenkins, Tanabe & Kiel, 2014

Nakrem, Hans Arne, 2017, Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard, Zootaxa 4329 (4), pp. 351-374 : 360

Abyssomelania sp.

( Fig. 6A–D )

2015 Gastropoda gen. et sp. indet. A; Hryniewicz et al. 2015a, table 1.

Description. Shell small for genus (6.4 mm high and 3.4 mm wide). Suture weakly incised. The maximum of whorl diameter slightly above the abapical suture. Lateral flanks smooth apart from opisthocline growth lines and faint and strongly inclined prosocline abyssomelanid riblets (see Kaim et al. 2014 for explanation). Base ornamented by numerous (11–12) broad spiral ribs intersected by growth lines without any knobs at the intersections. Protoconch, juvenile teleoconch and aperture not preserved.

Material and occurrence: One specimen (PMO 224.758) from seep #3, Sassenfjorden, Svalbard; late Tithonian, Late Jurassic.

Remarks. Abyssomelania species were previously known from Cretaceous Pacific seeps (Albian of California and Campanian of New Zealand). Now its palaeogeographic range extends to the Paleo-Barents Sea and its temporal range extends back to the latest Late Jurassic (Tithonian). Abyssomelania sp. from Svalbard is also the smallest known species of the genus and has the faintest abyssomelanid riblets, which are also very strongly prosocline compared to the other species of the genus.

Figures

FIGURE 6. A – D. Abyssomelania sp. (PMO 224.758), Seep deposit # 3, Sassenfjorden, Svalbard; late Tithonian (Late Jurassic). E – I.? Hokkaidoconcha sp., Seep deposit # 3; late Tithonian (Late Jurassic). E. PMO 224.759. F, G. PMO 224.760. H, I. PMO 224.761.