Sigmodon (Sigmomys) alstoni Thomas 1880

Sigmodon (Sigmomys) alstoni Thomas 1880, Proc. Zool. Soc. Lond., 1880: 691.

Type Locality: Venezuela, Sucre State, Cumaná.

Vernacular Names: Alston's Cotton Rat.

Synonyms: Sigmodon (Sigmomys) savannarum (Thomas 1901); Sigmodon (Sigmomys) venester (Thomas 1914) .

Distribution: Intermittently distributed in savannas over NE Colombia, N and E Venezuela, Guyana, Surinam, and N Brazil (regional aspects of range amplified by Husson, 1978; Linares, 1998; and Voss, 1992).

Conservation: IUCN – Lower Risk (lc).

Discussion: Subgenus Sigmomys . Suspected to be "individuals of South American representatives of S. hispidus with grooved incisors" (Hershkovitz, 1955 a:647), but distantly related to other species of Sigmodon according to phylogenetic interpretation of cytochrome b sequences (Peppers and Bradley, 2000; Peppers et al., 2002). Voss (1992) discerned no morphological or morphometric foundation for delineating subspecies, but Linares (1998) recognized savannarum and venester, along with the nominate form, as races for Venezuelan populations.