Dokuchaev (1997) recognizes the similarities of the northern, short-tailed, tri-colored shrews in the S. cinereus complex, as does van Zyll de Jong (1991), and suggests they are conspecific with the name S. jacksoni having priority:

• Sorex jacksoni jacksoni (Hall & Gilmore 1932) - Restricted to Saint Lawrence Island. (Type locality: Sevoonga (sic), two miles east of North Cape, St. Lawrence Island)
• Sorex jacksoni ugyunak (Anderson & Rand 1945) - Northwestern Alaska and east to Hudson Bay.
• Sorex jacksoni portenkoi (Stroganov 1956) - Northeastern Russia.

Species diagnosis

• Third upper unicuspid equal to or slightly larger than the fourth
• Fifth upper unicuspid not readily apparent
• Length of dentary usually less than 6.5mm
  
• Length of c1-m3 less than 4.1mm
  
• Height of coronoid process less than 3.2mm
• Pigment on i1 distributed in three sections
  
• i1 set at an angle less than 8 degrees from the
  horizontal ramus of the dentary
  
• Limited to Pribilof Islands
  
• Pelage tricolored

Literature cited

• Dokuchaev, N. E. 1997. The role of Beringia in migration and speciation of shrews. Byuleten' Dalnevostochonogo Otdeleniya Rossiyskoy Academii Nauk 2:54-61 (in Russian).
• Hall, E. R. and R. M. Gilmore. 1932. New mammals from St. Lawrence Island, Bering Sea, Alaska. University of California Publications in Zoology 38(9):391-404.
• van Zyll de Jong, C. G. 1991. Speciation of the Sorex cinereus group. Pp. 65-73 in The Biology of the Soricidae (J. S. Findley & T. L. Yates, eds.). Special Publication, Museum of Southwestern Biology, 1:1-91.