Анотація:
Karyological evidence of a middendorfii group vole representative occurrcnce in south-eastern Yakutia (lower Maya river), i. e. in an area formerly not included in their range. Chromosomal set of 2 examined females consists of 50 chromosomes, inorphologilally identical to the described Middendorf’s vole karyotype Range and habitat distribution data support their identification as M. Iiyperboreus.