Morphometric analysis of intraspecific variation in Microtus maximowiczii (Rodentia, Cricetidae) in relation to chromosomal differentiation with reinstatement of Microtus gromovi , stat. nov.
The vole Microtus maximowiczii Schrenck, 1858 is a widely distributed species inhabiting humid biotopes of the forest zone in East Asia. It comprises three subspecies: M. m. maximowiczii Schrenck, 1858, Microtus m. ungurensis Kastchenko, 1913, and Microtus m. gromovi Vorontsov, Boeskorov, Lyapunova and Revin, 1988. The description of the latter subspecies was based on one subadult individual only. Here, we present a morphological investigation of the three subspecies and relate the results to the karyological variation observed in M. maximowiczii. In a morphometric analysis, 124 skulls of the three subspecies were studied, including seven of M. m. gromovi, which have been collected near Ayan village at Ohotsk sea coast (Russian Far East). The samples of M. m. gromovi clustered separately from the other subspecies of M. maximowiczii. In average, M. m. gromovi proved to be considerably smaller than the others. The analysis of the third upper molar (M3) revealed that the majority of individuals of M. m. gromovi (from Ayan and from the coast of Lake Bol’shoe Toko) possessed a complicated shape of M3. In the karyological analysis, the number and morphology of chromosomes in all three M. m. gromovi individuals investigated were stable and equal: 2n = 44, NF = 60. While the same chromosome formula is also found in the other subspecies of this karyologically highly variable species, the individuals from Ayan possess peculiar characters: pericentric inversions in the first and fourth chromosome pairs, a large acrocentric chromosome and additional euchromatin in the 10th pair. In total, the results confirm a distinct systematic position of M. m. gromovi and consequently, this taxon should be raised to species status. A redescription of Microtus gromovi Vorontsov, Boeskorov, Lyapunova and Revin, 1988, stat. nov. is given.
Document Type: Short Communication
Affiliations: 1: Laboratory of Evolutionary Zoology and Genetics, Institute of Biology and Soil Science, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, Russia 2: Institute of Natural Resources, Ecology and Cryology, Siberian Branch of the Russian Academy of Science, Chita, Russia 3: Museum of Natural History Vienna, 1. Zool. Department, Laboratory of Molecular Systematics, Vienna, Austria
Publication date: February 1, 2009