[Pg 385]

University of Kansas Publications

Museum of Natural History

Volume 9, No. 13, pp. 385-388

May 12, 1958

A New Bog Lemming (Genus Synaptomys)

BY


J. KNOX JONES, JR.

University of Kansas

Lawrence

1958

[Pg 386]

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson

Volume 9, No. 13, pp. 385-388

Published May 12, 1958

University of Kansas

Lawrence, Kansas

PRINTED IN

THE STATE PRINTING PLANT

TOPEKA, KANSAS

1958

27-3033
[Pg 387]

A New Bog Lemming (Genus Synaptomys)

BY

J. KNOX JONES, JR.

In the autumn of 1952, I obtained a southern bog lemming,
Synaptomys cooperi, at Rock Creek State Fish Hatchery, Dundy
County, in extreme southwestern Nebraska. This locality of record
is the westernmost for the species in North America. Subsequently,
I reported this specimen in the literature (Univ. Kansas Publ., Mus.
Nat. Hist., 7:486, 1954), provisionally assigning it to Synaptomys
cooperi gossii, the subspecies occurring in eastern Nebraska.
In late November of 1956, J. R. Alcorn collected three additional
bog lemmings at the Rock Creek Hatchery.

These specimens from Dundy County represent a relict population
that differs in several characteristics from S. c. gossii, and that
differs also from all other subspecies of the species. This relict population
is, therefore, here given subspecific recognition.

Synaptomys cooperi relictus, new subspecies

Type.—Adult female, skin and skull, University of Kansas Museum of
Natural History no. 51617, from Rock Creek State Fish Hatchery, 5 mi. N,
2 mi. W Parks, Dundy County, Nebraska; obtained November 1, 1952, by
J. Knox Jones, Jr., original no. 995.

Distribution.—Known only from the type locality.

Diagnosis.—Size large for the species, both externally and cranially; dorsal
pelage dark; nasals broadly flared anteriorly (especially broad in relation to
nasal length); auditory bullae small; molariform tooth-rows and incisive
foramina long.

Measurements (in millimeters).—External measurements of the type specimen,
followed by those of another adult female (KU 72603), are: Total
length, 141, 145; length of tail-vertebrae, 24, 21; length of hind foot, 20, 20;
length of ear from notch, 11, 12. The type specimen weighed 46.3 grams.
Cranial measurements were taken in the manner described by Wetzel (Jour.
Mamm., 36:2-3, 1955) except that he did not record the occipitonasal length.
These cranial measurements of the type and KU 72603 are: Occipitonasal
length, 30.2, 29.8; condylobasilar length, 27.2, 27.1; zygomatic breadth, 18.1,
17.9; lambdoidal breadth, 14.2, 13.8; length of nasals, 8.2, 8.3; breadth of
nasals, 4.2, 4.0; length of rostrum, 6.6, 6.6; breadth of rostrum, 6.1, 5.9; breadth
of upper incisors, 4.6, 4.2; length of maxillary tooth-row, 8.5, 8.4; length of
incisive foramen, 5.8, 5.5; interorbital breadth, 3.1, 3.5.

Comparisons.—From Synaptomys cooperi gossii (specimens from eastern
Nebraska and eastern Kansas, including one topotype), S. c. relictus differs in:
[Pg 388]Dorsal coloration, in comparable pelages, darker, venter lacking buffy tinge;
skull averaging larger in all cranial dimensions (except rostral length, which is
approximately the same), especially breadth of upper incisors and length of
molariform tooth-rows; nasals broader anteriorly; auditory bullae nearly equal
in size, thus relatively smaller. From Synaptomys cooperi paludis (holotype
and paratypes) of Meade County, Kansas, S. c. relictus differs in: Skull averaging
smaller in all cranial measurements except rostral length and breadth
of upper incisors, which are approximately the same, and breadth of nasals,
length of incisive foramina and length of molariform tooth-rows, which measure
more; nasals relatively (48 per cent of length of nasals) as well as actually
broader anteriorly; anterior border of zygomatic plate more concave; auditory
bullae smaller; infraorbital foramina larger when viewed anterolaterally. S. c.
relictus closely resembles S. c. paludis in color and external proportions.

Remarks.—The total population of Synaptomys cooperi relictus
may be small because the only suitable habitat known to me for
these mice is the dense, grassy area, approximately 100 yards wide
and one mile long, around some of the rearing ponds and along the
creek at Rock Creek Hatchery. It has been taken there in association
with Cryptotis parva parva, Blarina brevicauda carolinensis,
Reithrodontomys megalotis dychei, Peromyscus maniculatus nebrascensis,
Microtus ochrogaster haydenii, and another relic, Microtus
pennsylvanicus finitis. All specimens of the newly named bog lemming
are from the border zone between the wet-substrate habitat
of M. p. finitis and the drier habitat occupied by M. o. haydenii.
Approximately 3000 trap nights produced the four known specimens.

S. c. relictus, like S. c. paludis, represents a relict population of
the more southwesterly distribution of the subgenus Synaptomys
during Wisconsin and post-Wisconsin times. Additional relict populations
likely will be found in the eastern Great Plains.

The new subspecies is intermediate in some features between
paludis and gossii. The type locality is separated from that of
paludis (14 mi. SW Meade, Meade County, Kansas) by a distance
of approximately 220 miles over habitats largely unsuitable
for bog lemmings. The nearest locality of record for S. c.
gossii to the east of the type locality of relictus is at Hunter, Mitchell
County, Kansas (see Cockrum, Univ. Kansas Publ., Mus. Nat.
Hist., 7:196, 1952), approximately 200 miles distant. The locality
of record of gossii in Nebraska nearest to the type locality of relictus
is even farther eastward—1 mi. N Pleasant Dale, Seward County
(KU 50188).

Specimens examined.—Four, from the type locality (KU 51617, 72601-03).

Transmitted March 11, 1958.