Pruvostiella (Pruvostiella) hermanni (Oppel, 1863)

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

Pruvostiella (Pruvostiella) hermanni (Oppel, 1863)

Plate 4 , figs 10-13, Plate 5 , figs 1-6; Fig. 4

1831 Unio ? and Trigonia ? - Herbert 272, pl. 17, fig. 4, 4a.

1833 Unio ? - Everest: 114, pl. 2, fig. 26.

*1863 Astarte hermanni Opp. - Oppel: 273, 297.

1865 Astarte unilateralis Sow. - Salter: 97, pl. 23, fig. 10. (non Sowerby, 1840).

1866 Astarte unilateralis , Sow. 1840 - Stoliczka: 90. (non Sowerby, 1840).

1866 Astarte spitiensis Stol. - Stoliczka: 91, pl. 9, fig. 1.

1866 Astarte hiemalis Stol. - Stoliczka: 91, pl. 9, figs 2-3.

1913 Astarte scytalis sp. nov. - Holdhaus: 444, pl. 100, figs 2-3.

1913 Astarte sowerbyana sp. nov. - Holdhaus: 443, pl. 99, figs 12, 13, 15, pl. 100, fig. 1.

1913 Astarte spitiensis Stoliczka - Holdhaus: 444, pl. 100, figs 4-8.

1913 Astarte hermanni Oppel 1863 - Holdhaus: 440, pl. 99, figs 7-11, 14.

1923 Astarte spitiensis Stol. - Trechmann: 279, pl. 13, fig. 1.

1923 Astarte cf. scytalis Holdhaus - Trechmann: 280, pl. 13, fig. 3.

1923 Astarte cf. sowerbyana Holdhaus - Trechmann: 280, pl. 13, fig. 2.

?1929 Astarte scytalis Holdhaus - Weir: 5, pl. 3, fig. 20.

1935 Astarte scytalis Holdhaus - Cox: 180, pl. 19, figs 4-5.

1953 Astarte spitiensis Stol. - Marwick: 107, pl. 11, figs 13, 15.

non 1956b Astarte (Pruvostiella) spitiensis Stoliczka - Agrawal: 109, pl. 10, fig. 3. (non Stoliczka).

?1959 Astarte scytalis Holdhaus - Jaboli: 49, pl. 6, fig. 6.

1998 Neocrassina (Pruvostiella) unilateralis (J. de C. Sowerby, 1840) - Kanjilal & Pathak: 35, pl. 1, fig. 8. (non Sowerby, 1840).

1998 Neocrassina (Pruvostiella) sowerbyana (Holdhaus, 1913) - Kanjilal & Pathak: 35, pl. 1, fig. 9.

Material.

Three right valves, four left valves, 16 articulated specimens, and two hinge fragments from the lower member at Langza (SNSB-BSPG 2020 XCIX 53, 57, 58, 59), two right valves, one left valve, 17 articulated valves, and six hinge fragments from the lower member at the Kaza-Hikkim road cut (SNSB-BSPG 2020 XCIX 55a, b), and two right valves, one left valve, nine articulated specimens and six hinge fragments from the lower member close to Tashigeng (SNSB-BSPG 2020 XCIX 54a, b).

Dimensions.

See Fig. 4 .

Description.

Shell highly variable in outline, longer than high (Fig. 4 ), moderately inflated. Anterodorsal margin concave, anteroventral margin convex, grading smoothly into the broadly arched ventral margin. Posteroventral margin well-rounded, posterodorsal margin faintly convex. Umbo prosogyrate, distinctly depressed, situated approximately one-fifth to one-eighth of shell length from the anterior end. Beaks small, lunule elongated, deep, bordered by sharp ridge (Plate 5 ); escutcheon lanceolate, bordered by distinct ridge. Ligament opisthodetic. Ornamentation consisting of widely spaced commarginal ribs in umbonal area only and extending for 10-15 mm ventrally. Remaining surface covered with irregular growth lines.

Hinge of right valve with three cardinals, 3b thin and inconspicuous, and one posterior lateral. Left valve with two cardinals and one short anterior and posterior lateral, respectively. Two pedal retractor muscle scars developed right underneath hinge plate, one more or less mesial, the second one close to the anterior adductor muscle scar. Inner shell margin strongly crenulated.

Remarks.

Due to their high morphological variability the specimens from the Spiti Shale Formation have been accommodated in several species in the past. Stoliczka (1866) recognised Astarte spitiensis , A. unilateralis , and A. hiemalis and Holdhaus (1913) A. sowerbyana , A. hermanni , A. scytalis and A. spitiensis , all occurring in the lower member where they form a characteristic association together with Palaeonucula cuneiformis and Grammatodon (Indogrammatodon) egertonianus ( Fürsich et al. 2021). Apart from the fact that intermediate forms exist between these species, usually two to four of these morphotypes co-occur within individual horizons. On ecological grounds it is highly unlikely that several closely related species with a more or less identical mode of life repeatedly co-occur within a community, and we therefore regard these forms as representing a single species, even though the end members of the morphological range are quite disparate. The oldest available name is Pruvostiella (P.) hermanni (Oppel, 1863).

Several authors (e.g., Cox 1965: 88; Stoliczka 1866; Holdhaus 1913; Gardner and Campbell 2002) assumed that the species occurs also in the Kachchh Basin on the western margin of the Indian Craton where it has been named Astarte major by J. de C. Sowerby (1840). However, the Kachchh specimens, although undoubtedly closely related, are more than three times the size of the Himalayan forms and thus unlikely conspecific. Gardner and Campbell (2002, p. 346) placed most of the large astartids from the Tethys Himalaya in Neocrassina unilateralis (J. de C. Sowerby, 1840), a view not followed here. Pruvostiella (P.) hermanni occurs from the Tethys Himalaya to New Zealand ( Trechmann 1923; Marwick 1953).

The record of Astarte scytalis Holdhaus from the Kimmeridgian? of East Africa ( Weir 1929, p. 5, pl. 3) is doubtful. The specimen may represent a juvenile Pruvostiella (Eoseebachia) major .

Genus Nicaniella Chavan, 1945

Figures

Plate 4. (1) Camptonectes (Camptochlamys) sp. from the upper member close to Demul Pass (SNSB-BSPG 2020 XCIX 14). (2) Chlamys (Chlamys) cf. textoria (Schlotheim, 1820). Incomplete right valve from the lower member at Langza (SNSB-BSPG 2020 XCIX 11). (3) Spondylopecten (Plesiopecten) subspinosus (Schlotheim, 1820). Internal mould of right valve from the lower member at the Kaza-Hikkim road (SNSB-BSPG 2020 XCIX 23). (4) Radulopecten cf. fibrosus (J. Sowerby, 1816). a, b, Fragment of a right valve from the? lower member near Demul (SNSB-BSPG 2020 XCIX 39). (5) Pectinidae indet. Slightly distorted internal mould of a single valve from the lower member along the Kazan-Hikkim road (SNSB-BSPG 2020 XCIX 17). (6) Plagiostoma? sp. B. Strongly crushed single valve with remains of shell from the lower member at Langza (SNSB-BSPG 2020 XCIX 35). (7) Plagiostoma? sp. A. a, b, Fragmented left internal mould with remains of the inner shell layer from the Ferruginous Oolite Formation near Zangla (SNSB-BSPG 2020 XCIX 36). (8) Trigonia? sp. Right internal mould from the top of the Ferruginous Oolite Formation at Zangla (SNSB-BSPG 2020 XCIX 24). (9) Vaugonia (Orthotrigonia) sp. Poorly preserved right valve from the lower member at Langza (SNSB-BSPG 2020 XCIX 25). (10 - 13) Pruvostiella (Pruvostiella) hermanni (Oppel, 1863). 10. Hinge of left valve from the lower member close to the pass to Tashigeng; Aa, anterior adductor scar; Apr, anterior pedal retractor scar (SNSB-BSPG 2020 XCIX 54 b). 11. Hinge of left valve from the lower member at the Kaza-Hikkim road cut; Cpr, central pedal retractor scar (SNSB-BSPG 2020 XCIX 59). 12. Hinge of right valve from the lower member close to the pass to Tashigeng; Apr, anterior pedal retractor scar. a, lateral view; b, dorsal view (SNSB-BSPG 2020 XCIX 54 b). 13. Articulated specimen from the lower member at Langza (SNSB-BSPG 2020 XCIX 59 a). a, left valve view; b, dorsal view.

Figure 4. Length plotted against height of Pruvostiella (P.) hermanni from the Spiti Shale Formation and of the holotypes of P. (P.) unilateralis (J. de C. Sowerby, 1840) and P. (Eoseebachia) major (J. de C. Sowerby, 1840) (= Seebachia (E.) sowerbyana (J. de C. Sowerby, 1840) in part).

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.