Population Structure and Origin of Some Ecological Forms of Сoregonus lavaretus pidschian from the Olenek River.

The results of morphogenetic analysis of sympatric forms/species of the Coregonus lavaretus pidschian (Coregonus pidschian) complex from the Olenek River basin are presented. It was demonstrated that the Olenek River basin was inhabited by three distant forms of whitefishes. Two of these forms, C. lavaretus pidschian n. brachymystax and C. lavaretus pidschian n. glacialis, were confined to the estuary, while the third form was found in the middle course of the river. It was demonstrated that all forms/species had similar numbers of gill rakers and perforated scales in the lateral line, while they were different in size and appearance. Analysis of the mtDNA ND1 gene sequence variation showed that these whitefishes belonged to phylogroups previously identified in the water bodies of the Taimyr Peninsula. The new whitefish form from the middle course of the Olenek River has the same mtDNA as glacial-plain whitefish, and according to allozyme analysis, it belongs to the group of East Siberian whitefishes, which indicates the hybrid nature of this form. [ABSTRACT FROM AUTHOR]