Hardella thurjii (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 : 28-33

Hardella thurjii (Gray, 1831)

Figs 19–21

Emys thurjii Gray, 1831a: 22 (nomen novum).

Emys thuryi Gray, 1831c: 8 (nomen oblitum).

Emys thuji Gray, 1831b (ex errore): pl. 73.

Emys flavonigra Lesson, 1831: 120 .

Emys thugi Gray, 1832 (ex errore): Directions.

Clemmys (Clemmys) thurgii Fitzinger, 1835: 123 (nomen novum).

Kachuga oldhami Gray, 1869: 200 .

Batagur falconeri Lydekker, 1885a: 187

Clemmys watsoni Lydekker, 1886a: 541

Hardella indi Gray, 1870: 58 .

Geoemyda pilgrimi Prasad & Satsangi, 1967 .

Emys thurgii – Gray 1844: 17.

Emys thurgi – Gray 1856 (“1855”): 21.

Clemmys thurgii – Strauch 1862: 32.

Batagur thurgii – Theobald 1868: 12.

Hardella thurgi – Gray 1870: 58.

Batagur (Hardella) thurgi – Anderson 1879: 764.

Hardella thurjii – Siebenrock 1909: 456.

Hardella thurgi – Smith 1931: 50.

Hardella thurjii thurjii – Wermuth & Mertens 1977: 40.

Hardella thurjii indi – Wermuth & Mertens 1977: 40.

Hardella thurji – Pritchard 1979 (ex errore): 193.

Hardella thurji thurji – Obst 1985: 221.

Type

Unknown ( Iverson 1992).

Material examined

INDIA • 1 specimen, holotype of Batagur falconeri ; Siwalik Hills ; Miocene–Pliocene; BMNH 39835 • 1 specimen; Siwalik Hills ; Miocene–Pliocene; BMNH R.890 • 1 specimen, holotype of Clemmys watsoni ; Gulf of Cambay , Gujarat, Piram Island ; Late Miocene–Pliocene; BMNH R.748 .

Type locality

“ India ” ( Iverson 1992).

Occurrence

Miocene/Pliocene – Recent.

Differential osteological diagnosis using shell characters

Hardella thurjii can be differentiated from other geoemydids by large carapace size (up to 60 cm in females), presence of hexagonal, nearly square second to fourth vertebrals, a first vertebral scute that is wider posteriorly, presence of an inflection at the margin of the gulohumeral sulcus, and an entoplastron that is not intersected by the humeropectoral sulcus.

Description of material examined

BMNH 39835 ( Fig. 19 ), holotype of Batagur falconeri – This is an almost complete shell, exceptionally well preserved, from the Miocene/Pliocene of the Siwalik Hills, likely of India, originally figured and described in three views by Lydekker (1885a: pls 23.1, 24.4). Our figures are overall comparable to those of Lydekker, although we see more details to the peripherals ( Fig. 19 ). The specimen clearly represents an adult female specimen based on overall size (carapace length greater than 40 cm). A small keel is present on neurals IV and VI. There are no signs of growth annuli. All neural bones have short anterior sides. The third neural is half one and a half time longer than the other neural bones. The cervical scute is present, longer than wide. The first vertebral scute is broader posteriorly and narrows anteriorly. The second and third vertebrals are much broader than the other vertebral scutes. The fifth vertebral has an anterolateral constriction. Marginal scutes IV–X overlap the adjacent costal bones. The anterior and posterior plastral margins are not preserved. The pectoroabdominal sulcus has lateral notches, suggesting the former presence of longitudinal keels as a juvenile. The pectoroabdominal sulcus does not intersect the hyo-hypoplastron suture and contacts the fifth marginal scute. Axillary and inguinal scutes are likely present.

BMNH R.748 ( Fig. 20 ), holotype of Clemmys watsoni – This specimen originates from the Late Miocene–Pliocene of Piram Island, Gulf of Cambay, Gujarat, India, was presented to the BMNH in 1886 by Col. J.W. Watson and figured and described in a small contribution from Lydekker (1886a: pl. 1). Our illustrations in three views overall confirm most of Lydekker’s observations, but we see fewer details along the neural column and the damaged portions of the costals and peripherals. The specimen is almost complete, full size, and misses some lateral peripheral bones (right and left), the anterior plastral margin, the posterior plastral lobe, and the right bridge ( Fig. 20 ). The specimen is likely an adult considering its size (carapace length greater than 15 cm) and perhaps a male specimen, as modern male individuals of H. thurjii reach up to 18 cm and lack intercostal fontanelles ( Das & Bhupathy 2009a). Most sulci and sutures of the carapace are visible, as well as a knob on neurals IV and VIII, indicating the presence of a median keel. Growth annuli are present. The cervical scute is as wide as long and lacks a posterior notch. The first vertebral scute is wider than long, its lateral sides converge anteriorly and lack an anterolateral constriction, and it contacts the first marginal scute. The neural bones are hexagonal and anteriorly short-sided. The third vertebral has straight lateral sides and the posterior margin has an anteriorly oriented inflection that crosses the suture between neural bones III–IV. The fifth vertebral scute has an anterolateral constriction. The pygal bone is completely intersected by the twelfth intermarginal sulcus. The humeropectoral sulcus is located posterior to the entoplastron. The pectoral scute contacts the fifth marginal. For a more extensive description of this specimen, we refer to Lydekker (1886a).

BMNH R.890 ( Fig. 21 ) – This specimen is from the Miocene/Pliocene of the Siwalik Hills, likely of India, was purchased by P.T. Cautley in 1840, but remained unfigured to date. It is a crushed, partial specimen, that probably represents an adult female considering its large size (carapace length greater than 20 cm). Both the anterior and posterior margins of the carapace are missing. Neural bones III and IV have a knob, indicating the presence of a median carapacial keel. Neural bones II–IV are hexagonal with anterior short sides. The first vertebral scute has anteriorly converging lateral sides. The third vertebral scute has straight lateral sulci. The posterior margins of the first and second pleurals are straight, placed over costals II and IV, respectively, and lack an anterior projection. Both the anterior and posterior plastral margins are not preserved. The plastron has two lateral longitudinal keels, which cross the lateral sides of the hyo- and hyoplastra. The humeropectoral sulcus is apparently located posterior to the entoplastron, which is not preserved. Inguinal scutes are likely present that contact the femoral scute.

Comments

We here attribute these specimens to Hardella thurjii based on the presence of a short median keel, large and square second and third vertebrals that are about the same width as the fourth vertebral scute, large inguinal scute, and an entoplastron that is not intersected by the humeropectoral sulcus. This confirms the synonymy of B. falconeri and C. watsoni with H. thurjii , as first suggested by Boulenger (1889) and later supported by Lydekker (1889a), TEWG (2015) and TTWG (2017). We furthermore follow Das (1994) by recognizing the synonymy of Geoemyda pilgrimi with H. thurjii (followed by TEWG 2015 and TTWG 2017) although we did not study the holotype of this species firsthand.

Figures

Fig. 19. BMNH 39835, holotype of Batagur falconeri Lydekker, 1885, here identified as a synonym of Hardella thurjii (Gray, 1831). A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.

Fig. 20. BMNH R.748, holotype of Clemmys watsoni Lydekker, 1886a, here identified as synonym of Hardella thurjii (Gray, 1831). A. Photograph of carapace. B. Illustration of carapace. C. Photograph of carapace in lateral view. D. Illustration of carapace in lateral view. E. Photograph of plastron. F. Illustration of plastron. Scale bar: 3 cm.

Fig. 21. BMNH R.890, referred to Hardella thurgi (Gray, 1831) by Lydekker (1889b), here identified as Hardella thurjii (Gray, 1831). A. Photograph of carapace. B. Illustration of carapace. C. Photograph of plastron. D. Illustration of plastron. Scale bar: 3 cm.