Age variation as the factor influencing on the exactness of identification of morphologically close species of mouse-like rodents

The analysis of morphometric features in two pairs of closed species of wool mice (Sylvaemus tauricus and S. sylvaticus) and voles (Terricola subterraneus and Microtus arvalis) is carried out. It is shown that the problems of diagnostics of morphologically closed species appear due to the coincidence of signs of the young stages of size-large species with the adult stages of lesser species. Increase in interspecies differences take place in oldest age groups