A new vole from Hall Island, Bering Sea

VOL. _Xlli, PP. 13-14 JANUARY 31, 1899

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

A NEW ^VOLE FROM HALL _ISLAND, BERING SEA.*

BY GERRIT

S.

MILLER,

^JR.

A _specimen

of Microtus collected

by ^Mr.

^C.

^H. Townsend on Hall

_Island,

Bering

Sea, represents

a

species distinct

from any

hitherto described. Itis a rather large

member

of

the

_typical

group

^of

^the subgenus

^Microtus,

and

is

more _nearly

related to

a Siberian

_species

which

I

suppose

^to

^be M.

kamtxchaticus

(Polyakoff) than

to

any

^of

^the known Alaskan members

of

the genus except M.

kadiacensis.

On account

ofits

remarkably

^short

tail it

may ^be

^called:

Microtus abbreviatus

_sp. nov.

Type,

? young

adult (skin

and

_{skull),No. ifftf,}UnitedStatesNational

Museum,

^collected

on

Hall _Island, Bering Sea,

September

8, 1885,

by

C. H.

Townsend.

Generalcharacters. Sizerather_large(hind foot, 23

mm.)

; tail shorter than hindfoot; plantartubercles,6_; earsconcealed in thefur_;

enamel

pattern essentially asin MicrotusarvalisofEurope.

Fur and

color.

The

fur is dense

and

_onlymoderately long about 12

mm.

_{in length}atmiddleofback but the specimen

was

taken

when

in themidstof the

autumnal

_molt,with the short

new

hairsof thewinter coatappearing^asadense

mat among

^therootsof the longer^fur.

As

the skinhas been preserved^{inalcohol for}

an unknown

period,fthe_original colorof theanimal cannot be determined with_certainty. Initspresent condition the dorsal surface is light yellowish brown,^duller

on

_head,

*Published

by

permissionof Secretary oftheSmithsonian Institution.

fMr.

Townsend

tells

me

thatthespecimen

was

_{preserveddry.} It

was

receivedattheNational

Museum

inSeptember,1886,

and

itssubsequent history^isnot

known.

It

was

found inabottleof alcoholinOctober,^1898.

4 Bior,.Soc.WASH., VOL. XIII,1899 (13)

14 Miller A New Vole from Bering

^Sea.

cleareron rump, palingonthesides tothesoiledbuff ofthe

under

_parts,

which

are _slightlydarker

on

chest. Tail bicolor,brownish _{above, yel} lowishwhite beneath. Feetdirty whitish.

Skull

and

teeth.

The

skullis imperfect, lacking the occipitals

and

one ofthe audital bullre. It resembles that of M. kamtschaticusveryclosely, but the rostrum is slightly narrower anteriorly, the

mandible

is less heavilybuilt,

and

the

bony

palate^isnoticeablydifferent inform. In the palate ofM.kamtschaticusthelateralbridges arebroad

and

welldeveloped

and

thelateral pitsare deep

and

_verynoticeable. InM.abbreviatusthe bridges are small

and

_{barely complete,} while the _pits

behind them

^are shallow

and

inconspicuous. In

no

one of the seven specimens ^of M.

kamtschaticus with

which

I have

compared

^{it is} the peculiar palate of M.abbreviatus closelyapproached.

Teeth _slightly smaller than in

M.

kamtschaticus,but

enamel

_pattern

essentiallythe

same

inthe

two

_species. M. abbreviatus,however, has the anterior loop of the frontlower molar_{distinctlylonger}thanin M. kamt schaticus. In M.kamtschaticus there is usually a well developed ^fourth outersalientangle

on

the_posteriorupper^molar. Thisisquiteabsentin M. abbreviatus,butthe characterisnot_{likely to}prove^constant.

Measurements.*' Total length, 120; ^tail vertebrae, 19 (pencil, 9); hind foot, 22.5; ear from meatus, 9.5; ear from crown, ^{6. Skull:} greatest length, 27; zygomatic breadth, 15; interorbital constriction, 4; nasals, 7.8; mandible,17.4; maxillary^tooth

row

_(alveoli),6.4; mandibulartooth

row

_(alveoli),G.(>.

General remarks. Microtus abbreviatus is closely related to both M.

kamtschaticus

and

M.kadiacensis, though^{in external}appearance^itsshort, densely haired^tailgives^ita

much

closerresemblancetothe

members

of thesubgenus Phaiomys. In cranial

and

dental charactersitdiffersfrom M.kadiacensis

much

asitdoes

from

M.kamtschaticus,sincethese

two

_species agreeclosely inpalate structure

and

intheformof the frontlowermolar.

*A11fromskinin alcohol.