Nephelomys pectoralis

Karyotype: 2n = 66 and FN = 94. Autosomal complement: nine medium to small metacentric and submetacentric pairs, six subtelocentric pairs (three large and three small), and 17 acrocentric pairs (one large and the remaining medium to small). Sex chromosomes: X, a large acrocentric; Y, a small submetacentric (Gardner & Patton 1976, pp. 4, Fig. 1B).