Oryzomys Antillarum - Taxonomy

Taxonomy

In his 1877 monograph on North American rodents, Elliott Coues mentioned two specimens of Oryzomys from Jamaica in the collections of the United States National Museum (USNM). According to Coues, the specimens were similar to the marsh rice rat (Oryzomys palustris) of the United States, but different in color. Although he wrote that they probably represented a separate form, he refrained from giving a scientific name to them because of the possibility that the form had already received a name he did not know of. The species was first formally described by Oldfield Thomas in 1898 based on a specimen that had been in the British Museum of Natural History since 1845. He recognized it as a separate species of Oryzomys, Oryzomys antillarum, but wrote that it was related to the mainland Central American O. couesi. Thomas suspected that the species was already extinct on Jamaica, but that it or a similar rice rat could still be found in the unexplored interior of Cuba or Hispaniola.

Revising North American Oryzomys in 1918, Edward Alphonso Goldman retained O. antillarum as a separate species, but conceded that it was so similar to mainland O. couesi that it may have been introduced on Jamaica. In 1920, Harold Anthony reported that remains of O. antillarum were common in coastal caves, suggesting that the species had previously been an important part of the diet of the barn owl (Tyto alba). In 1942, Glover Morrill Allen doubted that it was even a distinct species and in his 1962 Ph.D. thesis, Clayton Ray, who examined numerous cave specimens, agreed and retained it as only a "weakly differentiated subspecies" of Oryzomys palustris (which by then included O. couesi and other Mexican and Central American forms), Oryzomys palustris antillarum. Philip Hershkovitz came to the same conclusion in a 1966 paper. After O. couesi of Mexico and Central America was again classified as a species distinct from the marsh rice rat (O. palustris) of the United States, the Jamaican form came to be regarded as a subspecies of the former, Oryzomys couesi antillarum.

In a 1993 review, Gary Morgan reinstated the animal as a distinct species closely related to O. couesi, citing an unpublished paper by Humphrey, Setzer, and himself. Guy Musser and Michael Carleton, writing for the 2005 third edition of Mammal Species of the World, continued to classify the Jamaican form as part of O. couesi, but did not reference Morgan. However, in a 2006 review of the contents of Oryzomys, Marcelo Weksler and colleagues listed O. antillarum as a separate species, citing Morgan, and in a 2009 paper on western Mexican Oryzomys Carleton and Joaquín Arroyo-Cabrales did the same.

According to the classification by Carleton and Arroyo-Cabrales, Oryzomys antillarum is one of eight species in the genus Oryzomys, which occurs from the eastern United States (O. palustris) into northwestern South America (O. gorgasi). O. antillarum is further part of the O. couesi section, which is centered around the widespread Central American O. couesi and also includes various other species with more limited and peripheral distributions. Many aspects of the systematics of the O. couesi section remain unclear and it is likely that the current classification underestimates the true diversity of the group. Oryzomys previously included many other species, which were progressively removed in various studies culminating in the 2006 paper by Weksler and colleagues, which excluded more than forty species from the genus. All are classified in the tribe Oryzomyini ("rice rats"), a diverse assemblage of American rodents of over a hundred species, and on higher taxonomic levels in the subfamily Sigmodontinae of family Cricetidae, along with hundreds of other species of mainly small rodents.