Nicaniella (Nicaniella) cf. polymorpha (Contejean, 1860)

Fuersich, Franz T., Alberti, Matthias, Pandey, Dhirendra K. & Ayoub-Hannaa, Wagih S., 2022, Jurassic bivalves from the Spiti area of the Himalayas, northern India, Zitteliana 96, pp. 153-178 : 153

Nicaniella (Nicaniella) cf. polymorpha (Contejean, 1860)

Plate 5, fig. 7a-d

cf. 1860 Astarte polymorpha Contej. - Contejean: 266, pl. 11, figs 13-16.

Material.

A single articulated specimen from the lower member, Kaza-Hikkim road (SNSB-BSPG 2020 XCIX 42).

Description.

Specimen small-sized (H: 9.1 mm; L: 9.7 mm), rounded-triangular, slightly longer than high, moderately inflated. Anterodorsal margin concave, anteroventral margin convex, ventral margin faintly curved, posterodorsal margin long, straight, sloping, forming a rounded angle with the slightly truncated posteroventral margin. Umbones mesial, conspicuous, prosogyrate. Lunule oval, deeply sunk, bordered by sharp carina. Escutcheon long, lanceolate, sharply demarcated, extending to posterior end. Ventral shell margin strongly crenulated. Shell surface covered with 22 closely set, sharp commarginal ribs which are more widely spaced in the umbonal area. Internal features not seen.

Remarks.

Among the numerous Jurassic species of Nicaniella , the specimen is closest to Nicaniella polymorpha (Contejean,1860: 266, pl. 11, figs 13-16) from the Kimmeridgian of eastern France in outline and ornamentation, but that species is known only from its drawings. Therefore, we place our specimen in this species with reservation.

Order Cardiida Ferrusac, 1822

Figures

Plate 5. (1 - 6) Pruvostiella (Pruvostiella) hermanni (Oppel, 1863). 1. Crushed articulated specimen from the lower member at Langza (SNSB-BSPG 2020 XCIX 53). a, left valve view; b, dorsal view. 2. Crushed articulated specimen from the lower member close to the pass to Tashigeng (SNSB-BSPG 2020 XCIX 54 a). a, left valve view; b, right valve view. 3. Crushed articulated specimen from the lower member at the Kaza-Hikkim road cut (SNSB-BSPG 2020 XCIX 55 a). 4. Articulated specimen from the lower member at Langza (SNSB-BSPG 2020 XCIX 59 b). a, right valve view; b, left valve view. 5. Articulated specimen from the lower member close to the pass to Tashigeng (SNSB-BSPG 2020 XCIX 54 b). a, right valve view; b, dorsal view; c, left valve view. 6. Crushed articulated specimen from the lower member at the Kaza-Hikkim road cut (SNSB-BSPG 2020 XCIX 55 b). (7) Nicaniella (Nicaniella) cf. polymorpha (Contejean, 1860). Articulated specimen from the lower member at the Kaza-Hikkim road cut (SNSB-BSPG 2020 XCIX 42). a, right valve view, natural size; b, enlarged; c, dorsal view; d, left valve view. (8) Cryptocardia sp. Right internal mould with remains of shell from the lower member close to the pass to Tashigeng (SNSB-BSPG 2020 XCIX 40). (9) Integricardium (Integricardium) bannesianum (Contejean, 1860). Right internal mould with remains of shell from the Ferruginous Oolite Formation near Zangla (SNSB-BSPG 2020 XCIX 41). a, lateral view; b, dorsal view.