Analysis of Some Taxonomic Criteria in Lethenteron, Lampetra and Eudontomyzon

Lamprey larvae are extremely difficult target for taxonomists. So far, there are very few morphological characters that allow determining the taxonomic status of a particular specimen.

In the study is given a critical analysis of established as “classic” systematic criteria and the new ones, proposed recently.

It is shown that in genera Lethenteron, Lampetra and Eudontomyzon morphological criteria cannot be used as systematically significant features.

Shape and color of the caudal fin, color of the head - these existing criteria require clarification and further analysis.

Number of oocytes in a cross section cannot be used as a criterion, since as the number of oocytes greatly varies depending on the place of cross section, and also on the degree of maturity of gonads.

It is also shows that for genera Lampetra and Lethenteron such criteria like the structure and pigmentation of precursor, which vary greatly within a single population, may not be appropriate.