Karyotype, morphology and taxonomic status of Calomys expulsus (Rodentia, Sigmodontinae)

CIBELE R. BONVICINO; FRANCISCA CUNHA ALMEIDA

MAMMALIA

WALTER DE GRUYTER & CO

Año: 2000 vol. 64 p. 339 - 351

0025-1461

Calomys expulsus has been considered a junior synonym or a subspecies of Calomys callosus. To clarify its taxonomic status we carried out karyologic and morphologic studies of C. expulsus and Calomys tener from different Brazilian localities and performed morphometric comparisons between them and C. callosus. Karyologic data showed that C. expulsus (2n = 66) differed drastically from C. callosus (2n =36, previously reported for Paraguayan specimens). On the other hand, C. tener and C. expulsus shared the same diploid number (2n = 66) but differed in fundamental number and in the amount and distribution of constitutive hetero- chromatin. Morphometric analyses showed that C. teuer differed from C. expulsus and C. callosus mainly in size, whereas C. expulsus and C. callosus despite being similar in size differed in shape. Morphometricand karyologic analyses indicated that these are three different species.