Neacomys tenuipes

The diploid number of 56 was reported by Pérez-Zapata et al. (1996).

Another different karyotype for a Neacomys species was reported by Aniskin (1994), with 2n = 30–32 and FN = 38, plus 1 to 6 B chromosomes (See also Weksler & Bonvicino 2015a). Additionally, five karyotypes were described for the genus by Silva et al. (2015, 2017, 2019), for specimens from Pará, Brazil: Neacomys sp. cytotype 1 (Silva et al. 2015; referred as Neacomys sp. D by Silva et al. 2019); Neacomys sp. cytotype 2 (Silva et al. 2015; referred as Neacomys sp. C by Silva et al. 2019); Neacomys sp. A (Silva et al. 2017); Neacomys sp. B (Silva et al. 2017); and Neacomys sp. E (Silva et al. 2019).