Cryptocardia sp.

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

Cryptocardia sp.

Plate 5, fig. 8

Material.

A single right valve internal mould with remains of shell from the lower member close to the pass to Tashigeng (SNSB-BSPG 2020 XCIX 40).

Description.

Specimen small, subequilateral, well-inflated, nearly as long as high (H: 17.2 mm; L: 16.6 mm). Umbo mesial, prominent, broad, protruding beyond hinge line, orthogyrate; beaks slightly prosogyrate and distinctly incurved. Anterior margin convex, ventral margin broadly arched, posterodorsal margin oblique, nearly straight, grading smoothly into rounded posteroventral margin. Posterodorsal margin forming a rounded shoulder with posterior margin. Two narrow parallel grooves, separated by equally narrow shell interval, extending from posterior side of umbo to posteroventral end of shell. Shell surface covered with fine, dense, commarginal striae. Hinge features not seen.

Remarks.

The diagnostic feature of Cryptocardia , two parallel radial ridges on the inside of the right valve, are clearly seen in the present internal mould as grooves. The genus has been erected by Palmer (1974) based on material from Pliensbachian to Callovian strata. Palmer established four new species based on differences in the outline of the shell and the size of the umbones. The present specimen cannot be accommodated in any of the four species, but is closest to his C. morrisi from the Callovian of Tanzania. As only a single specimen is available, we refrain from creating a new species and, instead, keep it in open nomenclature.

Genus Integricardium Rollier, 1912

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.