Aegialomys Weksler, Percequillo & Voss 2006

The genus Aegialomys comprises four species, A. baroni (Allen 1897), A. galapagoensis (Waterhouse 1839) (that includes A. bauri (Allen 1892)), A. ica (Osgood 1944), and A. xanthaeolus (Thomas 1894), that inhabit the northern Trans-Andean South America, in a region that extends from central–southern Ecuador to Southern Peru, including in its range the Galapagos Archipelago (Weksler et al. 2006; Prado & Percequillo 2013; Percequillo 2015a; Prado & Percequillo 2016; Prado & Percequillo 2018). Gardner & Patton (1976) described the karyotypes of A. bauri and A. xanthaeolus as essentially identical in all aspects (2n = 56, FN = 58). However, the same specimens karyotyped and identified as A. xanthaeolus by Gardner & Patton (1976) were recently reviewed by Prado & Percequillo (2016), highlighting that these specimens belong to A. baroni and A. ica . Moreover, as Prado & Percequillo (2018) synonymized A. bauri under A. galapagoensis, the karyotype of the former was attributed tentatively to the latter.

Karyotype: 2n = 56 and FN = 58. Autosomal complement: two small metacentric and submetacentric pairs, and 25 acrocentric pairs (one distinctly large and the remaining large to small decreasing in size). Sex chromosomes: X, a large acrocentric; Y, a small acrocentric (Gardner & Patton 1976, pp. 6, Fig. 2D). The karyotypes of A. xanthaeolus was currently unknown.