Title: A New Species of Pocket Gopher (Genus Pappogeomys) From Jalisco, Mexico
Author: Russell, Robert J.
Language: English
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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, México


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, México

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 Michoacán, and, like most of the mountainous terrain in
this region of México, 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, México; 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 México.

_Transmitted August 30, 1956._


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Transcriber's Notes:

Bold text is shown within =equal signs=.

Italic text is shown within _underscores_.





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