Cryptical nature of morphometric variation in diploid-poliploid spined loach network (Cypriniformes, Cobitidae, Cobitis) of the Lower Danube

Introduction.  The paper devoted to morphometric variation investigation of spined loaches network from Lower Danube consisting of two parental species (C. elongatoides, C. tanaitica) and three hybrid biotypes (C. 2 elongatoides -- C. tanaitica, C. elongatoides -- 2 tanaitica, C. elongatoides -- tanaitica) which identified by the allozymes Purpose. The purpose of the work was to verify the significance of the factor of geographic variability in determining the affiliation to different species and biotypes by means of morphometric indices. Methods.  It was used standard morphometry of the body form and size by means by 23 measurements and 26 indexes, multidimensional statistics (method of the main components) and unidimensional statistics. Results.  The obtained results prove that only 55% of females can correctly identify by means of the body measurements, while only 28% by the indexes. Despite the significant difference between most single characters, nonetheless, their application to distinguish between species and biotypes causes considerable difficulties, since in all cases of pairwise comparisons there are significant transgressions. Conclusion. The use of individual measurements or body indices, or their complex, does not make it possible to distinguish between species and biotypes even within the same group. This means that the geographic factor, if it alters the morphological differences of species, but its effect in this case is very small and can be neglected.