Pectinodonta borealis, Nakrem, 2017

Nakrem, Hans Arne, 2017, Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard, Zootaxa 4329 (4), pp. 351-374 : 354-355

? Pectinodonta borealis sp. nov.

( Fig. 3D–H )

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

Diagnosis: Surface covered with thick commarginal ribs. Aperture elongated, oval. Apex slightly subcentral. Holotype: PMO 217.516, H = 1.8 mm, L = 4.1 mm, W = 3.3 mm.

Type locality and age: Seep #9, Sassenfjorden, Svalbard ; late Berriasian, Early Cretaceous. Other material: Two additional specimens (one illustrated PMO 224.752) from the type locality. Description. Protoconch not preserved. Shell patelliform, elongate, oval; width is 81% of length. Apex moderately high, heavily eroded, situated slightly subcentrally; height is 43% of length. Shell exterior covered with thick concentric ribs. Radial ornament very weak, consisting of straight and faint radial riblets. Apertural margin straight in lateral view. Muscle scars not visible.

Remarks. The concept of genera in Pectinodontidae is based mainly on radular characters ( Sasaki et al. 2003). A slight difference in the apex position delimits, though tenuously, the shells of Pectinodonta and Bathyacmaea . The Sassenfjorden limpet has a slightly subcentral apex, so we decided to place it, though with hesitation, in Pectinodonta . The most similar species to? Pectinodonta borealis sp. nov. is Pectinodonta waitemata Marshall, 1985 , from Miocene flysch deposits with plant and wood material from New Zealand. Pectinodonta waitemata also has strong concentric ridges and faint radial ornament; however, its apex is positioned much more eccentrically. The Oligocene Pectinodonta palaeoxylodia Lindberg & Hedegaard, 1996 from a wood-fall in Washington State, USA differs in having a stronger radial ornament than commarginal ( Lindberg & Hedegaard 1996).

Distribution. Type locality only.

Etymology. Northern in Latin.

Figures

FIGURE 3. A – C. Hikidea svalbardensis sp. nov. Seep deposit # 9, Sassenfjorden, Svalbard; late Berriasian (Early Cretaceous); holotype (PMO 217.574). D – H.? Pectinodonta borealis sp. nov. Seep deposit # 9, Sassenfjorden, Svalbard; late Berriasian (Early Cretaceous). D, E, G. Holotype (PMO 217.516). F, H. Internal mould (PMO 224.752).