Batagur 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 : 13-16

Genus Batagur Gray, 1856

Figs 10–11

Type species

Batagur baska ( Gray, 1830) .

Differential osteological diagnosis using shell characters

A representative of Batagur can be diagnosed by the presence of a large carapace size (median carapace length of more than 40 cm in adults), a well-developed bridge, well-developed axillary and inguinal buttresses, neural scutes with anterior short sides, a long third neural bone, a short, anteriorly truncated gular scute, an entoplastron that is not intersected by the humeropectoral sulcus and a short anal notch.

Material examined

INDIA • 1 specimen, holotype of Batagur cautleyi Lydekker, 1885 ; Siwalik Hills ; Miocene–Pliocene; BMNH 39834 .

COUNTRY UNKNOWN • 1 specimen; IM E.176 .

Description

BMNH 39834 ( Fig. 10 ), holotype of Batagur cautleyi – This an almost complete shell from the Miocene/ Pliocene of the Siwalik Hills, likely of India, showing the majority of sulci and of the sutures along the center of the carapace. It was originally figured by Lydekker (1885a: pl. 24.1), but our observations reveal many additional sutures. There are no signs of growth annuli. The specimen likely is an adult female due to its large size (carapace length greater than 54 cm). A small protuberance on neural IV suggests the previous presence of a median keel. A cervical scute is present. The first vertebral scute is longer than wide and shows a lateral constriction. Neurals II–IV have anteriorly short sides, but neural V has a short left posterior side, which is probably abnormal. The sulcus between the second pleural and the third vertebral is almost straight. The anterior plastral margin is straight and lacks an inflection on the contact of the gularohumeral sulcus. The pectoroabdominal sulcus contacts the sulcus between fifth and sixth marginal scutes. The anal notch is not preserved in this specimen. No plastral sutures can be seen.

IM E.176 ( Fig. 11 ) – This is a well-preserved specimen that lacks provenance data and appears to be unpublished. The majority of sutures and sulci are clearly visible. This is an adult specimen due to its large size (carapace length greater than 35 cm), but its gender is unknown. A median carapacial keel is present on the posterior parts of the carapace and is strongly marked over neurals IV and VI. The carapace is rather domed at its center, with no signs of growth annuli. Vertebral scutes are subrectangular and have equally sized anterior and posterior margins. Neurals II to VI are anteriorly shortsided. Gular scutes appear to be wider than long and overlap part of the entoplastron. The humeropectoral sulcus is located posterior to the entoplastron. The pectoroabdominal sulcus does not intersect the hyohypoplastron suture and has two lateral notches, suggesting the former presence of parasagital plastral keels at the bridge.

Comments

We attributed BMNH 39834 and IM E.176, the type series of Batagur cautleyi , to Batagur indet. based on their massive size, highly domed carapace, and presence of an axillary notch and rather straight anterior plastral margin. However, we cannot identify these specimens to species level even though they display unique character combinations. See Discussion ( Batagur cautleyi from the Siwalik Hills) for additional details.

Figures

Fig. 10. BMNH 39834, holotype of Batagur cautleyi Lydekker 1885, here identified as Batagur sp. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.

Fig. 11. IM E.176, previously undescribed, here identified as Batagur sp. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.