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
26-5801
[Pg 359]
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.
[Pg 360]
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[Pg 361]
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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