Chapter I

UNIVERSITY OF KANSAS PUBLICATIONS

MUSEUM OF NATURAL HISTORY

Volume 9, No. 11, pp. 357-361

January 21, 1957

A New Species of Pocket Gopher (Genus Pappogeomys) From Jalisco, Mexico

BY

ROBERT J. RUSSELL

UNIVERSITY OF KANSAS LAWRENCE 1957

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Harrison B. Tordoff

Volume 9, No. 11, pp. 357-361 Published January 21, 1957

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1957

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A New Species of Pocket Gopher (Genus Pappogeomys) From Jalisco, Mexico

BY

ROBERT J. RUSSELL

J. R. Alcorn collected a number of pocket gophers of the genus _Pappogeomys_ in the states of Jalisco, Nayarit, and Colima. The bulk of this material was obtained in 1949 and 1950. Full treatment of these interesting pocket gophers will be given by the author in a future publication.

Among the _Pappogeomys_ collected by Alcorn were three specimens from the high Sierra del Tigre, an isolated range not previously sampled for pocket gophers. The Sierra del Tigre is situated in southern Jalisco and western Michoacan, and, like most of the mountainous terrain in this region of Mexico, is volcanic in origin. To the south the Sierra del Tigre descends abruptly to lower elevations of the arid coastal plains, uninhabited by gophers of this genus. The small pocket gopher occurring in the Sierra del Tigre seems to be an undescribed species of the genus _Pappogeomys_ which may be known as

=Pappogeomys alcorni= new species

_Type._--Adult female, skull and skin; No. 39806, University
of Kansas, Museum of Natural History; 4 mi. W Mazamitla,
6600 ft., Jalisco, Mexico; October 18, 1950; obtained by J.
R. Alcorn, original number 12835.

_Distribution._--Known only from the Sierra del Tigre, and
probably occurs only at higher elevations within the
geographic limits of this isolated range of mountains.

_Diagnosis._--Size medium for genus (see measurements); tail
naked, short relative to length of head and body; hind foot
short; hairs of upper parts and underparts Plumbeous basally
and Orange-Cinnamon apically (capitalized color terms after
Ridgway, Color Standards and Color Nomenclature, Washington,
D. C., 1912); large nasal patch Cinnamon-Buff in two
specimens, but Pale Pinkish-Buff in holotype; white throat
spot small and inconspicuous, throat mostly bright
Cinnamon-Buff; auricular patch pure Plumbeous, hairs lacking
cinnamon-colored tips; tarsi with Cinnamon-Buff hairs;
dentition as in _P. bulleri_ except that enamel plate of
posterior wall of M1 reduced to a vestige present only on
inner fourth, outer three-fourths of posterior wall of M1
without trace of enamel; zygomata slender, bowed outward;
jugal long, widely separating maxillary and squamosal arms
of zygoma; skull deep (measured from a point on the frontal
to a point on the palate directly below and between the
maxillary teeth); rostrum narrow and short; nasals broadly
truncate posteriorly, and not decurved anteriorly; narrow
across mastoid processes of squamosals; anterior palatine
foramina small and rounded in outline, not slitlike.

_Comparisons._--Compared with _Pappogeomys bulleri_, the
only other named species of the genus, _P. alcorni_ differs,
as follows: Nasal patch cinnamon or buffy instead of white;
enamel plate of posterior wall of M1 reduced to inner fourth
rather than developed completely across posterior wall of
tooth; nasals broadly truncate posteriorly instead of narrow
and emarginate; anterior palatine foramina short and round
instead of long and slitlike.

_Measurements._--The type and an adult female topotype (in
parentheses) measure, as follows: Total length, 210 (210);
length of tail, 61 (63); length of hind foot, 29 (28);
condylobasal length, 38.0 (36.9); basilar length, 32.8
(31.9); breadth across zygomata, 24.2 (24.8); palato-frontal
depth, 15.0 (14.8); palatal length, 24.7 (24.1); length of
nasals, 12.7 (12.8); breadth of braincase, 18.1 (17.5);
breadth across mastoid processes of squamosals, 21.5 (21.4);
breadth of rostrum, 8.4 (8.1); length of rostrum, 16.9
(16.3); alveolar length of maxillary tooth-row, 9.3 (8.8);
breadth across angular processes of rami, 26.1 (26.2).

_Specimens examined._--Three, all from Jalisco, as follows:
4 mi. W Mazamitla, 2; 3 mi. WSW Mazamitla, 1.

_Remarks._--The features which distinguish _Pappogeomys alcorni_ seem to be beyond the range of variation in _Pappogeomys bulleri_. In view of the absolute quality of the differences between _P. alcorni_ and _P. bulleri_, it seems best to regard the former as a species, rather than as a subspecies of _P. bulleri_. Moreover, it seems unlikely that actual intergradation of the two species can occur, since the broad, low valleys between the higher terrain, where pocket gophers of this genus are found, do not offer suitable habitat for _Pappogeomys_.

In every example of _P. bulleri_ that I have seen (more than 100 specimens, representing all of the named subspecies) the anterior palatine foramina are long and slitlike and the nasals are always narrow and emarginate posteriorly, whereas in _P. alcorni_ the anterior palatine foramina are short and round and the nasals broad and squarely truncate posteriorly. The conspicuous nasal patch of _P. alcorni_ is large and bright cinnamon or buffy, and, although the nasal patch may be large in some subspecies of _P. bulleri_, in each specimen possessing the patch the hairs are whitish with little or no trace of pigmentation.

One of the most interesting features of _P. alcorni_ is the reduction of enamel on the posterior wall of the first upper molar. In _P. alcorni_ the enamel present is thick, but it occurs only on the inner one-fourth of the posterior wall of the tooth. The enamel is always complete in _P. bulleri_; but in some old individuals it becomes thin with wear, and at a casual glance may appear to be partly or entirely absent. Close examination under magnification reveals, however, in every specimen of _P. bulleri_, a fine line of enamel completely across the posterior wall. It seems that the posterior enamel plate of M1 is disappearing in both _P. bulleri_ and _P. alcorni_. In both species the enamel on the posterior wall of M1 does not extend down the crown so far as the level of the alveolus, whereas the anterior plate of enamel on M1, for example, extends well below the alveolus of the tooth. Even though disappearance of the posterior enamel seems to be a trend in both species, it has proceeded farther in _P. alcorni_ than in _P. bulleri_. Examination of the posterior wall of M1 in _P. alcorni_ disclosed only the vestige of enamel on the inner side of the tooth, and no enamel, not even a thin plate, was present on the remainder of the posterior wall of the tooth.

The name _alcorni_ is proposed as a token of appreciation to Joseph Raymond Alcorn, whose collecting has greatly enriched our knowledge of the mammals of Mexico.

_Transmitted August 30, 1956._

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Transcriber's Notes:

Bold text is shown within =equal signs=.

Italic text is shown within _underscores_.