Pangshura Gray, 1856

Garbin, Rafaella C., Bandyopadhyay, Saswati & Joyce, Walter G., 2020, A taxonomic revision of geoemydid turtles from Siwalik-age of India and Pakistan, European Journal of Taxonomy 652, pp. 1-67 : 23-27

Genus Pangshura Gray, 1856

Figs 16–18

Type species

Pangshura tecta ( Gray, 1830) .

Differential osteological diagnosis using shell characters

A member of Pangshura can be diagnosed by the presence of a tectiform carapace, strong median carapacial keel, a pleural I/II sulcus with an anteromedial process, a pleural IV/vertebral V sulcus contacting the tenth marginal, a fourth vertebral scute that is much longer than wide and that is strongly constricted anteriorly, and an octagonal fourth neural ( Garbin et al. 2018).

Material examined

INDIA • 1 specimen; Yamuna-Ganges River basin, Siwalik Hills ; Miocene–Pliocene; BMNH 39837 • 1 incomplete specimen; Siwalik Hills ; Miocene–Pliocene; BMNH 17435 • 1 specimen, original of “ Emys namadicus ”; Madhya Pradesh, Central Narmada Valley , Muwar and Doomar Villages ; Late Pleistocene; IM E.110 .

Description of material examined

BMNH 39837 ( Fig. 16 ) – This is an almost complete shell from the Miocene/Pliocene of the Yamuna or Ganges River basins in the Siwalik Hills of India originally figured and described in dorsal view by Lydekker (1885a: pl. 22.3). The specimen is not particularly well preserved, but many more sutures are visible than apparent from the figure of Lydekker. The size (carapace length greater than 15 cm) indicates that it represents an adult female. A small keel is present between neural II and suprapygal II. There are no signs of growth annuli. Neural bones II, III, and VII are hexagonal with anterior short sides. Neural IV is octagonal. The third vertebral scute has a strong posterior keel, but no midline prominence. The posterior margin of the first and second pleural scutes have long finger-like anterior projections that intersect costal I and III, respectively. The fifth marginal scute contacts costal bones III and IV. The anterior and posterior plastral margins are not completely preserved. The entoplastron is not intersected by the humeropectoral sulcus. The pectoroabdominal sulcus has lateral notches, which suggest the former presence of longitudinal keels, does not intersect the hyo-hypoplastral suture, and contacts the fifth marginal scute. Axillary and inguinal scutes were likely present. The anal notch is deep.

BMNH 17435 ( Fig. 17 ) – This is a small incomplete specimen (total length of 9 cm) from the Miocene/ Pliocene of the Siwalik Hills, likely of India, that was presented to BMNH by P.T. Cautley in 1840 and figured and described in dorsal view by Lydekker (1885a: pl. 22.1). The specimen probably represents an adult male based on its small size and consists of the center of the shell, missing the anterior, posterior as well as part of lateral carapace margins. Some additional sutures are apparent relative to the original figure of Lydekker (1885a). A strong median keel is present, running from the most anterior to the most posterior region of the specimen. The carapace has a tectiform shape in anterior view (not illustrated). There are no signs of growth annuli or intercostal fontanelles. A cervical scute is present. The first vertebral scute is small, with straight lateral margins. The second vertebral scute is hexagonal, with shorter posterolateral margins, and a straight sulcus between the second and third vertebral. The third vertebral scute is pentagonal, has straight lateral margins and a small posterior projection into the fourth vertebral. The fourth vertebral scute is only partially preserved, but constricted anteriorly as strongly as other representatives of Pangshura . The interpleural sulcus I–II lies over the suture between costal I and II, and intersects it anteriorly, without a finger-like projection. The interpleural sulcus II–III has a small anterior projection that almost intersects the suture between costal III and IV. The anterior and posterior plastral margins are not preserved. The entoplastron is not intersected by the humeropectoral sulcus. The hyo-hypoplastral suture does not overlap the pectoroabdominal sulcus and contacts peripheral V laterally. The axillary and inguinal scutes are likely present. The fourth, fifth, and sixth marginals form the well-developed bridge.

IM E.110 ( Fig. 18 ), original of “ Emys namadicus ” Theobald, 1860 (nomen nudum) – This specimen is a well-preserved shell of a small individual (total length of 8 cm) from the latest Pleistocene of Muwar-Doomar, Central Narmada Valley, India, originally named by Theobald (1860) but only later figured in dorsal view and described by Lydekker (1885a: pl. 22.2). Although we observe fewer sulci and sutures than originally documented by Lydekker, most are well preserved. The presence of a hyo- hypoplastral fontanelle suggests that this is likely a juvenile specimen. A strong median carapacial keel is present, which is at its highest at the posterior region of the third vertebral scute. There are no signs of growth annuli marks. The first vertebral scute has a wide anterior margin followed by a constriction of the lateral margins. The second vertebral scute is hexagonal, subquadrangular, and as long as broad. The third vertebral scute is pentagonal and pointed posteriorly. The fourth vertebral scute is rhomboid, with a slight anterior constriction, and its posterior margin overlaps the suture between the eighth neural bone and the first suprapygal. The sulcus between the first and second pleural scutes is almost straight, overlapping the suture between costal I and II. The sulcus between the second and third pleurals is directed anteriorly in the dorsal portion, without an anterior projection or finger-like process. The anterior and posterior plastral margins are missing. The bridge is well developed with the fourth, fifth, and sixth marginals overlapping the hyo- and hypoplastra. The pectoroabdominal sulcus does not intersect the hyo-hypoplastral suture. The inguinal scute is likely present.

Comments

The three herein referred specimens in our opinion lack characters that would allow identifying them to species level. This contradicts in part the original assessments of Lydekker (1885a). See Discussion ( Pangshura specimens section) for further details.

Figures

Fig. 16. BMNH 39837, referred to Pangshura flaviventer Günther, 1864 by Lydekker (1885a), here identified as Pangshura sp. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.

Fig. 17. BMNH 17435, referred to Pangshura sp. by Lydekker (1885a), herein confirmed. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.

Fig. 18. IM E.110, referred to Pangshura flaviventer Günther, 1864 by Lydekker (1885a), here identified as Pangshura sp. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.