Some questions of cytogenetics, hybridization and systematics of the Acipenseridae

N. I. Nikoljukin Research Institute of Sea Fisheries and Oceanography, Moscow

Investigation of chromosome complexes in Acipenseridae has shown that a series of species of this family such as - Huso huso, Acipenser ruthenus, A. stellatus, A. nudiventris are characterized by a low chromosome number (about 60) differing strongly from A. gueldenstaedti whose chromosome number is more than twice higher (above 130). Owing to this, the first four species when crossed among themselves yield fertile hybrids while each crossed separately with A. gueldenstaedti produce hybrids either partly fertile or completely sterile. Consequently the most stressed cytogenetical boundary lies not between the genera Huso and Acipenser, but within the limits of the latter among its species. In connection with this a question arises whether it was justified to form separate genus Huso including Huso huso and exclude the latter from the genus Acipenser to which it had belonged since Linneus time is as much as the morphological differences between them are not so considerable.