Robertsonian chromosomal variation in subalpine voles Microtus (Terricola) (Rodentia, Arvicolidae) from Greece

Sixteen specimen of Microtus (Terricola) collected in subalpine meadows of the Pindos and Iti mountains were karyotyped. All 11 animals from the Pindos mountain had the same karyotype with 2n = 42, NF = 42. The individuals collected on Iti mountain had a karyotype with 2n = 40, NF = 42 characterized by a large pair of metacentric chromosomes. The two karyotypes were closely related and one might have derived from the other by a Robertsonian centric fusion/fission. In both karyo­types the X and Y chromosomes were large acrocentrics. The karyotypes of the voles studied were more similar to that described for M. (T.) thomasi than to the other species of Terricola known in Greece.