Patterns of Phenetic Diversity and Taxonomy of the Ide <i>Leuciscus idus</i> (Cypriniformes, Cyprinidae) from Water Bodies of Russia and Adjacent Countries

Abstract

Using the methods of population morphology, we studied the structure of phenetic diversity of the ide Leuciscus idus (L.) from the water bodies of the Russian Federation and some neighboring countries. We analysed our own collection and literature data on meristic characters of external morphology, axial skeleton, as well as the pharyngeal teeth formula. The main features contributing to population differentiation were the number of lateral line scales, total vertebrae count, caudal and pre-caudal vertebrae ratio. It was shown that the strong positive relationships of the first two features with the geographical latitude of fish habitats is associated, first of all, not with the direct influence of physical factors functionally dependent on latitude, but with particular (sub)speciation processes in river basins and dispersal of evolutionarily derived forms to the north. The results obtained are discussed in terms of evolutionary trends in the subfamily Leuciscinae and call for a taxonomic revision of the L. idus species in its current volume with elevation of the former subspecies L. idus oxianus to a species rank.