Polymorphism and karyotype divergence in taimens of the Hucho genus

Karyotypes of Siberian taimen Hucho taimen from the Manoma River (Amur basi n) were investigated. The karyotypes examined differed in chromosome number from 2n = 82 to 2n = 83; chromosome arm number was NF = 112. These differe nces, as well as the difference in the karyotype of Siberian taimen from th e lower flow of the Amur River (2n = 83) described earlier, are due to Robe rtsonian polymorphism of one pair of large submetacentric chromosomes. The nucleolus organizer regions are located on the short arms of one or two sub telocentric chromosomes of different pairs. The probable sequence of karyot ype divergence in taimens of the Hucho genus is discussed.