Relationships within the Holarctic Sorex arcticus — Sorex tundrensis Species Complex

Systematics of Holarctic Sorex arcticus — Sorex tundrensis species complex has been m dispute; the current l i terature places North Ameri-can and Eurasian populations in S. arcticus, separated by S. tundrensis in the Yukon and in Alaska. Results of morphometric analysis of the three populations indicate that the Eurasian shrews more closely re-semble tundrensis than arcticus, and they are referred to that taxon. The fundamenta l numoer of autosomes in arcticus (NFa = 34) also differs f rom that of the Eurasian populations of tundrensis (NF = 52, 56; NFa=48, 52)); unfortunately North American tundrensis have not been karyotyped. A map of the distribution of the Eurasian subspecies is presented: chromosome analysis of specimens assigned to 5. t. sibiriensis indicate that there are probably two distinct species in this area, but nomenclatural changes are considered premature, pending fur ther study