Palaeonucula stoliczkai Cox, 1940

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

Palaeonucula stoliczkai Cox, 1940

Plate 1, fig. 3a, b

*1940 Nucula (Palaeonucula) stoliczkai sp. nov. - Cox: 20, pl. 1, figs 21-23.

1956 Nucula (Palaeonucula) stoliczkai Cox - Agrawal: 52, pl. 7, fig. 3b.

1980 Palaeonucula stoliczkai Cox - Kanjilal: 339, pl. 1, figs 13-14.

1995 Palaeonucula stoliczkai Cox 1940 - Jaitly et al.: 158, pl. 2, figs 7-8.

Material.

One flattened articulated specimen from the Ferruginous Oolite Member at Langza (SNSB-BSPG 2020 XCIX 34).

Description and remarks.

The laterally strongly compressed specimen (H: 8.6 mm, L: 11.9 mm) is rounded trigonal in outline and longer than high. The ventral margin is strongly convex, the anterior margin obliquely truncated, forming a blunt angle with the ventral margin and a very obtuse angle with the faintly convex anterodorsal margin. The posterior margin is narrowly rounded. The umbo is prominent. The rounded anterior umbonal ridge extends to the anteroventral margin. Due to the compressed nature of the shell, features such as lunule could not be observed. The surface of the shell is covered with fine commarginal growth lines. Internal features not seen.

Although the hinge could not be observed, the specimen can be safely placed in P. stoliczkai as it closely resembles Cox’ species in outline.

Subclass Autobranchia Grobben, 1894

Order Arcida Gray, 1854

Figures

Plate 1. (1, 2) Palaeonucula cuneiformis (J. de C. Sowerby, 1840). 1. Left valve from the lower member at Langza (SNSB-BSPG 2020 XCIX 26 a). 2. Left valve from the lower member at Langza (SNSB-BSPG 2020 XCIX 26 b). (3) Palaeonucula stoliczkai Cox, 1940. Laterally crushed articulated specimen, lower member at Langza (SNSB-BSPG 2020 XCIX 34); a, left valve view; b, right valve view. (4) Megacucullaea cf. kraussii (Tate, 1867). Internal mould of articulated specimen with remains of shell from the lower member near Chichim (SNSB-BSPG 2020 XCIX 1); a, right valve view; b, dorsal view. (5 - 7) Grammatodon (Indogrammatodon) egertonianus (Stoliczka, 1866). 5. Articulated specimen from the lower member near the pass to Tashigeng (SNSB-BSPG 2020 XCIX 4). a, left valve view; b, dorsal view. 6. Laterally crushed articulated specimen from the lower member along the Kaza-Hikkim road (SNSB-BSPG 2020 XCIX 3 b); right valve view. 7. Dorso-ventrally compacted articulated specimen from the lower member at Langza (SNSB-BSPG 2020 XCIX 6); right valve view. (8, 9) Grammatodon (Cosmetodon) sp. from the lower member along the Kaza-Hikkim road. 8. Right valve (SNSB-BSPG 2020 XCIX 2 a). 9. Right valve (SNSB-BSPG 2020 XCIX 2 b). a, lateral view; b, dorsal view. (10) Anopaea? Fragmented right valve from the upper? member at Langza (SNSB-BSPG 2020 XCIX 67).