Chromosomal variation in Ctenomys pilarensis, a recently described species from Eastern Paraguay (Rodentia, Octodontidae).

M.D. GIMENEZ; J.R. CONTRERAS; C.J.BIDAU

MAMMALIA

WALTER DE GRUYTER & CO

Lugar: Berlin; Año: 1997 vol. 61 p. 385 - 398

0025-1461

Ctenomys pilarensis Contreras, 1993 occurs in the Department of Nembucu in eastern Paraguay, Its patchy distribution consists of numerous isolated populations which are subjected to the periodic fluctuations of the surrounding marshes. Individuals from four populations were analyzed karyotypically revealing that the species is chromosomally polytypic. The karyotype of individuals from the type locality (Yatayty) consists of 2n=48 chromosomes including two pairs of large subtelocentric and 21 pairs of telocentric autosomes. Individuals from Mayor Martinet have 2n=50 chromosomes with one large subtelocentric pair plus 23 pairs of telocentric autosomes. Individuals from Paso Pucu and Desmochado share the same karyotype of 2n=48 that includes one large subtelocentric, one small metacentric and 21 telocentric pairs of autosomes. The X and Y chromosomes have the same morphology and G-band pattern in all populations examined. The fundamental number (FN) is 50 in all individuals examined. The different karyotypes are related through robertsonian changes that probably show monobrachial homologies.