Cytogenetic analysis of four species of the genus Alsodes (Anura: Leptodactylidae) with comments about the karyological evolution of the genus.

A comparative cytogenetic analysis of Alsodes pehuenche, A. vanzolinii, A. verrucosus and A. aff. vittatus show that all four species share the same diploid number 2n = 26; the fundamental number is 50 in A. vanzolinii and 52 in A. aff. vittatus, A. pehuenche and A. verrucosus. The karyotypes of A. pehuenche and A. aff. vittatus are described for the first time; the C-band patterns, the NOR locations and Q-band patterns are also described for the first time for the four species. C-band patterns are species specific and useful to identify the taxa. The usefulness of the chromosomal data in taxonomy and systematics of Alsodes species is discussed. Transformation of euchromatin into heterochromatin and centric fissions and translocations are proposed as the main mechanisms that govern the chromosomal evolution of the frog genus Alsodes.