Fossil Land Tortoises (Testudines: Testudinidae) from the Dominican Republic, West Indies, with a Description of a New Species

Abstract

A new fossil tortoise, Chelonoidis dominicensis, is described from a flooded cave in La Altagracia Province in the southeastern Dominican Republic on the island of Hispaniola. The holotype, and only known specimen, includes a nearly complete shell, skull, and appendicular skeleton. The new Dominican species, Chelonoidis dominicensis, shares morphological features with the Bahamian tortoise, Chelonoidis alburyorum, and the Cuban tortoise, Chelonoidis cubensis. Chelonoidis dominicensis can be distinguished from C. alburyorum by its weak prognathous-shaped rostrum, stronger and sharper vomerine septum, more angular posterior skull margins, distinctive caudal hump as seen in shell profile, the centrum of first dorsal vertebra narrow without a strong ventral keel, massive sacral buttresses, weak presacral and sacral ribs, more tapered anterior plastral lobe with prominent gulars, elevated gular shelf. An interclavicular sculpture (bird face) occurs on the internal surface of the entoplastron, composed of a massive brow-line and an elongated, narrow keel (beak). Chelonoidis dominicensis is distinguished from C. cubensis (based on incomplete specimens), by its more narrow anterior plastral lobe and gulars, oval entoplastron, a strong wedge-shaped xiphiplastral notch, and a slight indentation at the junction of the cervical sulcus. The West Indian tortoises are allied with Galapagos tortoises, Chelonoidis nigra species complex, and possibly Chaco tortoises, Chelonoidis chilensis, based on morphology. These relationships are further supported by DNA evidence.A second tortoise, Chelonoidis marcanoi, was recently named from dry caves in Pedernales Province, in the southwestern part of the country. The designated holotype for C. marcanoi is a right humerus, but this element is inadequate to differentiate taxa in the West Indian genus Chelonoidis; thus, we consider C. marcanoi a nomen dubium. The concept of multiple populations of tortoises on Hispaniola has merit and is discussed in terms of biotic patterns associated with south and north paleo-islands, which are separated from each other by the Hispaniolan Rift Valley.