Morphological studies on collared lemmings (Rodentia, Arvicolidae, Dicrostonyx) from Bolshevik Island of the Severnaya Zemlya Archipelago, with notes on evolution and taxonomic position.

Abstract

The variation of molar patterns and lower jaw of collared lemmings from the Bolshevik Island is analyzed. In all teeth except m2 the morphotype henseli is dominant. Morphotype simplicior is the second most common morphotype in M3. Such type of dentition was typical for the lemmings of the Late Pleistocene and within the recent collared lemmings of Palaearctic was not recorded until now. Morphotype variation in the sample from Bolshevik Island is most similar to that in the sample from the Late Pleistocene Betovo site (36 thousand years BP). By the structure of the lower jaw lemmings from Bolshevik Island differ both from all recent subspecies of the genus, known karyomorphs, mtDNA phylogroups, and lemmings from Betovo.