Mammalogy lab 4: Order Rodentia; Family Muridae (mice, rats, lemmings and voles) Order Rodentia, Family Muridae, Subfamily Arvicolinae— voles and allies
1) molars with triangles of dentine surrounded by enamel 2) zygomatic arches parallel or nearly so Ondatra zibethicus—muskrat
1) largest skull in B.C. exhibiting arvicoline teeth 2) conspicuous postorbital processes squarish
Lemmus trimucronatus (sibiricus)—brown lemming
upper cheek teeth
lower cheek teeth
1) re-entrant angles deeper on outer side of upper cheek teeth 2) triangles present on both sides of lower cheek teeth 3) skull conspicuously larger than Synaptomys Synaptomys borealis—northern bog lemming
lower cheek teeth
1) re-entrant angles deeper on outer side of upper cheek teeth 2) triangles absent on outer sides of lower cheek teeth 3) lateral grooves on upper incisors (hard to see) Synaptomys borealis Lemmus trimucronatus Phenacomys intermedius—heather vole
inner side
ant post
outer side
1) inner re-entrant angles deeper than outer re-entrant angles on lower molars Myodes gapperi—southern red-backed vole
1) bony palate terminates as a shelf (not a median ridge) between the last molars 2) posterior edge of palate completely fused in adults Myodes rutilus—northern red-backed vole
1) bony palate terminates as a shelf (not a median ridge) between the last molars 2) posterior edge of palate incompletely fused in adults Myodes rutilus Myodes gapperi Microtus pennsylvanicus—meadow vole
ant post
upper cheek teeth
1) 2nd upper molar with 3 triangles and round posterior loop Microtus pennsylvanicus Most widespread vole in N America – Most of Canada and N USA (central and E). NOT found in coastal BC or pacific USA. Microtus oeconomus—tundra vole
post post ant ant
lower cheek teeth upper cheek teeth
1) 1st lower molar with 4 triangles 2) 2nd upper molar with 3 triangles, but no posterior loop
Microtus longicaudus—long-tailed vole M. montanus—montane vole M. richardsoni—water vole M. oregoni—creeping vole M. townsendii—Townsend’s vole
post post
ant ant
lower cheek teeth upper cheek teeth
1) 1st lower molar with 5-6 triangles 2) 2nd upper molar with 3 triangles, but no posterior loop Microtus oregoni—creeping vole
ant post
upper cheek teeth
1) 3rd upper molar with 3 (not 4) inner angles Microtus oregoni
Only found in very SW BC and down Pacific cost to NW California Microtus richardsoni—water vole
1) when viewed dorsally, upper incisors protrude conspicuously beyond nasals 2) incisive foramina taper posteriorly to narrow slits Microtus longicaudus—long-tailed vole Microtus montanus—montane vole Microtus townsendii—Townsend’s vole
1) when viewed dorsally, upper incisors protrude inconspicuously or not at all beyond nasals Microtus townsendii
• Found on Vancouver island and very SW mainland Canada, down Pacific coast to NW California Microtus montanus
• Found in mountain meadows and valleys in S BC and NW USA Microtus longicaudus
• Found throughout BC, but not on (Vancouver island); N to Alaska and S to NW and central USA. • Generally uncommon but widespread Order Rodentia, Family Muridae, Subfamily Murinae: Old World mice and rats
1) molars with 3 rows of cusps without triangles 2) postorbital processes absent or inconspicuous Mus musculus—house mouse
1) upper incisors notched
Rattus norvegicus—Norway rat Rattus rattus—black or ship rat
1) zygomatic plate extends anteriorly from zygomatic process of maxilla
Order Rodentia, Family Muridae, Subfamily Neotominae: North American mice and rats
1) molars with 2 rows of cusps without triangles 2) postorbital processes absent or inconspicuous Neotoma cinerea—bushy-tailed woodrat
1) arvicoline-like teeth, but without conspicuous triangles 2) zygomatic plate extends anteriorly from zygomatic process of maxilla
Peromyscus keeni—Keen’s mouse Peromyscus maniculatus—deer mouse
1) cusps of molars rounded and arranged in 2 rows 2) upper incisors not grooved or notched Reithrodontomys megalotis—western harvest mouse
1) cusps of molars rounded and arranged in 2 rows 2) upper incisors grooved Peromyscus maniculatus
Reithrodontomys megalotis