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 alhuryorum, and the Cuban tortoise, Chelonoidis cuhensis. Chelonoidis dominicensis can be distinguished from C. alhuryorum by its weak prog¬ nathous-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 distin¬ guished from C. cuhensis (based on incomplete specimens), by its more narrow anterior plas-1 National Museum of the Bahamas/Antiquities, Monuments and Museum Corporation, Marsh Harbour, tral 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 popula¬ tions 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 Riff Valley.

Ancient mitogenomics elucidates diversity of extinct West Indian tortoises

“…If that was the case, then the two colonizers must have been very similar genetically, given the low amount of genetic divergence of tortoises across the island group. As far as known, the extinct giant tortoises from the Greater Antilles, which would seem to be the likely source region of the Bahamian tortoises, are morphologically clearly distinct 11 , 21 . We cannot exclude, however, that these differences reflect morphological plasticity, a phenomenon well known from many other tortoise taxa 50 – 53 .…”

“…Alternatively, the ancestral taxa on the Greater Antilles may still be undiscovered or known only by material too fragmentary to discern the crucial morphological characters. (The majority of tortoise fossils from the Greater Antilles are represented only by very incomplete material 21 ). Unfortunately, the only sample from the Greater Antilles that we studied (ulna from the holotype of C. dominicensis , radiocarbon-dated to the early Holocene) did not yield aDNA sequences, so that genetic evidence must await further investigation.…”

“…Seventeen subfossil bone samples of Chelonoidis were studied (Fig. 1 ), originating from the West Indies ( n = 12) and mainland South America ( n = 5), including material from the holotype of C. dominicensis 21 from the Dominican Republic, a sample of the holotype of C. lutzae 7 and three additional samples of C. cf. lutzae from Argentina, and one sample of an undescribed giant species of Chelonoidis from Venezuela 6 .…”

“…Red rectangle in inset map corresponds to enlarged map sector. Open circles: unstudied material 5 , 6 , 9 – 11 , 21 , yellow circles: samples unsuccessfully processed for aDNA, red circles: samples successfully processed for aDNA. Grey areas show the shelf to a depth of 200 m. Map was created using ArcGIS 10.4 ( https://www.esri.com/en-us/arcgis/about-arcgis/overview ) and Adobe Illustrator CS6 ( http://www.adobe.com/products/illustrator.html ).…”

Assesssing the role of humans in Greater Antillean land vertebrate extinctions: new insights from Cuba

“…Amerindian (Orihuela, 2019). There are no known extinct amphibians described so far, and only 16 one reptile, Chelonoidis cubensis (Albury et al, 2018). 17…”