Sigmodontomys Allen 1897

Monotypic genus represented by S. alfari (Allen 1897), found throughout trans-Andean lowland and lower montane forests in Colombia, Venezuela, and Ecuador, besides Central American lowland forests from Panamá to Honduras (Pine et al. 2012; Prado & Percequillo 2013; Weksler 2015b).

Karyotype: 2n = 56 and FN = 54. Autosomal complement: 27 acrocentric pairs large to small decreasing in size. Sex chromosomes: X, a large-medium acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 13, Fig. 6A).