Batagur kachuga (Gray, 1831)

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 : 16-19

Batagur kachuga (Gray, 1831)

Figs 12–13

Emys lineata Gray, 1831c: 9 .

Emys kachuga Gray, 1831b : pl. 74.

Batagur ellioti Gray, 1862: 264 .

Kachuga fusca Gray, 1870: 56 (part).

Batagur bakeri Lydekker, 1885a: 190 .

Clemmys (Clemmys) lineata – Fitzinger 1835: 123.

Batagur lineata – Gray 1856 (“1855”): 35.

Batagur lineatus – Günther 1864: 39.

Batagur elliotti – Günther 1864: 40.

Clemmys ellioti – Strauch 1865: 88.

Kachuga lineata – Gray 1870: 56.

Batagur kachuga – Theobald 1876: 19. — Praschag et al. 2007: 439.

Kachuga kachuga – Smith 1931: 131.

Type

Unknown ( Iverson 1992).

Material examined

INDIA • 1 specimen, holotype of Batagur bakeri ; Siwalik Hills , Yamuna-Ganges River basin; Miocene– Pliocene; BMNH 39835a • 1 specimen; Siwalik Hills ; Miocene–Pliocene; BMNH R.891 .

Type locality

“ India ”, restricted by Smith (1931) to “N. India ” ( Iverson 1992).

Occurrence

Miocene/Pliocene–Recent.

Differential osteological diagnosis using shell characters

Batagur kachuga can be differentiated from other species of Batagur by the presence of an elongated fourth vertebral scute that covers the fourth to eighth neural bones and second and third vertebral scutes with straight lateral margins.

Description of material examined

BMNH 39835a ( Fig. 12 ), holotype of Batagur bakeri – This specimen is from Miocene/Pliocene of the Siwalik Hills of India (Yamuna or Ganges River basins) and was presented to BMNH by General W.E. Baker. It was initially figured and described by Lydekker (1885a: pl. 23.2). Our observations mostly agree with those of Lydekker (1885a), although we note an irregularity on the right side of the neural II/III contact and damage that must have incurred over the course of the last century to the anterior margin of the plastron. This is an almost complete specimen, with a well-preserved shell, and perhaps represents an adult female considering its large size (carapace length greater than 50 cm) compared with extant specimens. Most sulci and sutures are visible on the carapace, but only the sulci are apparent on the plastron. The specimen shows no signs of growth annuli or carapacial keels. The cervical scute is present and broader than long. The vertebral scutes are square shaped and with equidimensional anterior and posterior margins. The first vertebral scute has straight lateral margins, but lacks constrictions. The third vertebral scute is broader than long. All available neurals have anteriorly short sides, with exception of the left side of neural II, which displays an abnormality consisting of a supernumerary bone. The anterior margin of the fourth vertebral runs over neural IV. The bony bridge is well developed. The anterior plastron margin is not preserved anymore, but its original configuration is documented in Lydekker (1885a). The pectoroabdominal sulcus with lateral notches suggests the former presence of longitudinal keels that did not intersected the hyo-hypoplastral suture. The anal portion of the plastron not preserved.

BMNH R.891 ( Fig. 13 ) – This specimen is from the Miocene/Pliocene of the Siwalik Hills, likely of India, and was presented to the British Museum by P.T. Cautley in 1840. It has not been figured previously. This specimen has an incomplete carapace and an almost complete plastron. The carapace consists only of neurals I–IV, a part of costals I–IV and some peripherals. There are no signs of carapacial keels or growth annuli, indicating that this is probably an adult specimen. Two large fontanelles are present, which suggests that this is perhaps a male individual. Neurals II and III are hexagonal with anteriorly short sides. The second and third vertebral scutes have straight lateral sides. The posterior margins of the first and second pleural scutes are straight and cross over costals II and IV, respectively. The anterior and posterior plastral margins are not preserved. A strong axillary notch is present. The entoplastron is not crossed by the humeropectoral sulcus. The hyo-hypoplastral suture contacts peripheral V and does not overlap the pectoroabdominal sulcus. Inguinal scutes are present that contact the femoral scutes.

Comments

We confirm the previously established identification of these two specimens as Batagur kachuga , due to their large carapace size (greater than 50 cm), highly domed carapace (for BMNH 39835a), presence of a second vertebral that is as long as wide with straight lateral margins, a third vertebral that is hexagonal with short posterolateral sides (visible in BMNH 39835a), and a large plastron with medially converging humeropectoral sulci. This confirms the synonym of Batagur bakeri with Kachuga lineata , as originally proposed by Boulenger (1889) and supported by Lydekker (1889a), TEWG (2015) and TTWG (2017).

Figures

Fig. 12. BMNH 39835a, holotype of Batagur bakeri Lydekker, 1885, here identified as synonym of Batagur kachuga (Gray, 1831). A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.

Fig. 13. BMNH R.891, referred to Cachuga lineata (Gray, 1831) by Lydekker (1889b), here identified as Batagur kachuga (Gray, 1831). A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.