Melanochelys tapani, Garbin & Bandyopadhyay & Joyce, 2020

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 : 47-48

Melanochelys tapani nom. nov.

Fig. 32

Nicoria tricarinata var. sivalensis Lydekker, 1889b: 100 .

Geoemyda tricarinata Smith, 1931: 95 .

Melanochelys tricarinata TEWG, 2015: e.46.

Type

BMNH 39839, a near complete fossil shell ( Fig. 32 ).

Differential osteological diagnosis using shell characters

Melanochelys tapani can be differentiated from other Melanochelys species by the following combination of characters: presence of three carapacial keels, a highly domed shell, hexagonal second to fourth vertebrals that are wider than long, and a large cervical scute.

Etymology

The specific name is in honour of the late Prof. Tapan Roy Chowdhury of the Indian Statistical Institute, the distinguished teacher and researcher of Indian fossils, who established a school of vertebrate palaeontologists in India.

Material examined

Holotype

INDIA • Siwalik Hills ; Miocene–Pliocene; BMNH 39839 .

Type locality and horizon

Miocene/Pliocene of the Siwalik Hills, likely of India.

Description of type

BMNH 39839 ( Fig. 32 ), holotype of Melanochelys tapani nom. nov. and subsequent holotype of Nicoria tricarinata sivalensis – This is an almost complete carapace associated with a partial plastron from the Miocene/Pliocene Siwalik Hills, likely of India, originally figured and described by Lydekker (1885a: pl. 21.4; 1889b: fig. 21). Our observation of this specimen overall confirms the observations of Lydekker (1889b), but we also illustrate the plastron and a less idealized carapace that lacks sutures ( Fig. 32 ). A part of the anterior margin of the carapace and all posterior peripherals are missing. Total carapace length is approximately 17 cm. Most sulci are preserved on the carapace, but only very few on the plastron. Three longitudinal carapacial keels are present. The lateral keels are closer to the center of the carapace than to the borders. A cervical scute is present. The first vertebral scute is wider than long and contacts the first marginal scutes. The second to fifth vertebral scutes are about the same size and wider than long. The sulcus between the second pleural and third vertebral is straight. The sulcus between the second and third pleural contacts the fifth marginal scute. Most of the plastral surface is not preserved. The anterior plastron margin straight and lacks a median notch. The gular scutes are longer than wide. The pectoroabdominal sulcus contacts the sixth marginal scute.

Comments

See Discussion for further details.

Figures

Fig. 32. BMNH 39839, holotype of Nicoria tricarinata var. sivalensis Lydekker, 1889, here identified as Melanochelys tapani nom. nov. A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.