Melanochelys cf. moldavica, Chkhikvadze, 1983

Yanenko, V. & Kovalchuk, О., 2023, Late Miocene Turtles Of Grytsiv (Western Ukraine) With Rodent Gnaw Marks On The Carapace Surface, Zoodiversity 57 (4), pp. 311-322 : 315

Melanochelys cf. moldavica

M a t e r i a l. One right xiphiplastron NMNHU-P AR 405 ( FIg. 2 , D–E), one neural plate AR 404, one costal plate AR 403 ( FIg. 2 , C).

Description. The posterior lobe of the right xiphiplastron is smoothly narrowed. The femoro-anal notch is weakly expressed. The short xiphiplastral processes are rounded and not bent posteriorly. The moderate anal notch is pointed. The transverse ridge on the upper surface of the caudal part of the xiphiplastron is moderately developed, and it is almost parallel to the posterior edge of the bone. The neural plate is wide, hexagonal, with a distinct bend of the medial keel. The fragments of costal plates are uniform in width.

Remarks. The right xiphiplastron from Grytsiv is morphologically similar to that in Melanochelys moldavica from the middle Sarmatian of Moldova ( Chkhikvadze, 1983) except for the more pronounced transverse ridge on the upper surface of its caudal part. It further differs from the respective bones of the other geoemydid turtles (e. g., Sarmatemys , Sakya etc.) in having a much less developed femoro-anal notch and shorter xiphiplastral processes. Other skeletal elements (neural and costal plates) share general geoemydid morphology and we tentatively assign them to the same taxon.

Figures

Fig. 2. Turtle remains from the late Miocene of Grytsiv: A–B — Emys sp., xiphiplastron NMNHU-P AR402/4 (A), marginal scute NMNHU-P AR 402/1 (B); C–E — Melanochelys cf. M. moldavica Chkhikvadze, 1983, costal plate NMNHU-P AR 403 (C), right xiphiplastron NMNHU-P AR 405 (D–E); F, I — Trionychidae indet., shell fragments NMNHU-P AR 401/1 (F), AR 401/2 (I); G–H — Testudo chernovi Khosatzky, 1948, nuchal NMNHU-P AR 406 (G), type specimen after Khosatzky (1948 a: FIg.1), modiFIed (not to scale). Scale bars equal 5 mm in A–C, F–G and I, 10 mm in D and E.