CHROMOSOMAL COMPLEMENT AND TAXONOMIC POSI TION OF SEVERTSOV WILD SHEEP (OVIS AMMON SEVERTZOVI)

A review of the genus Ovis taxonomy indicates;that the position of (Se vertsov wild sheep from the Nura-Tau mountains (Kyzyl-Kum desert) is u nclear. Its range fails between urial sheep (O. vignei, 2n = 58) and a rkhar sheep (O. ammon, 2n = 56). A specimen of O. ammon severtsovi she ep from the region, similar to terra typica, was studied. It has 2n = 56 and a karyotype consisting of 2 pairs of metacentric and 25 pairs o f acrocentric autosomes, a large acrocentric X and a minute biarmed Y. The (Giemsa-band analysis permitted accurate pairing of all chromosom es. The banding patterns of the largest pair of metacentrics were iden tical to those of the largest biarmed chromosomes in all wild and dome stic sheep of the genus Ovis. The banding patterns of the second pair of metacentric chromosomes were identical to the third pair of biarmed chromosomes in al sheep of the genus Ovis with 2n = 54 (muflons and a ll domestic sheep) and to the third largest pair of metacentric in the 2n = 52 karyotype of Siberian snow sheep (O. nivicola). The G-banded karyotype of Severtsov's wild sheep is consistent for all subspecies o f Arkhar-Argali (O. ammon) karyotyped Numerical assignment of acrocent ric chromosome equivalents based on the fundamental Ovis karyotype and other Caprini that gave rise to the biarmed chromosomes of severtzovi are 1 and 3, 5 and 11 for these two largest metacentric pairs, respec tively. The G-band patterns of Eurasian and North American wild sheep are compared with severtzovi, and their homologies are related to the chromosomal evolution of Ovis. The first data on heterochromatic area (C-banding) of wild sheep and ArgNOR's-banding patterns of O. a. sever tzovi are described. Based on the diploid chromosome number, Severtsov 's sheep should be considered as subspecies of the Arkhar-Argalis grou ps and not of the Urial one. Hypotheses of chromosomal evolution in th e genus Ovis are reviewed from the standpoint of their consistency wit h paleontological wild sheep and Pleistocene evolution of the Holarcti c fauna.