Occasional papers of the Museum of Natural History, the University of Kansas

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LIBRARY

OCCASIONAL PAPERS NOV 5 1971

of the HARVARD

MUSEUM OF NATURAL HISTORY
The University of Kansas
Lawrence, Kansas

NUMBER 5, PAGES 1-7 JUNE 18, 1971

A NEW SPECIES OF SPINY POCKET MOUSE
(GENUS LIOMYS) FROM JALISCO, MEXICO

By
Hugh H. Genoways^

In the course of a systematic revision of the spiny pocket mice of
the genus Liomys, a series of large, brightly colored mice from
several localities in southeastern Jalisco was studied. Individuals in
this series appeared to be morphologically distinct from mice typical
of Liomys pictus pJantinaremis Merriam, 1902, "taken in the same
traplines at several localities, and from specimens of Liomys irrorahis
joUscensis (J. A. Allen, 1906), a taxon that also occurs in southeastern
Jalisco. My studies now have progressed to the point where the
large and distinctively colored mice from Jalisco can be defined as a
new species which is distinct from, but closely related to, Liomys
pictus. The new species is named and described below.

Liomys spectabilis new species

HoJotype. — Adult male, skin and skull, no. 96051 Museum of
Natural History, The University of Kansas ( KU ) ; from 2.2 mi NE
Contla, 3850 ft, Jalisco; obtained on 20 September 1963 by Percy L.
Clifton; original no. 5244.

Geographic distribution. — Known only from southeastern Jalisco
(presently known limits from a point 8.5 mi S Mazamitla, 5300 ft in
the north to a place 8 mi SW TecaHtlan in the soutli — see Fig. 1 ) .

Description. — Size large, both externally and cranially (see
measurements and Table 1 ) ; skull proportionally similar to that of
L. pictus, but much larger (Fig. 2); six plantar tubercles; dorsal
coloration reddish brown, lateral stripe bright ochraceous; under-

^ Research Assistant, Division of Mammals, Museum of Natural History,
University of Kansas.

OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

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KILOMETERS
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Museum of Natural History
University of Kansas

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Fig. 1. — Geographic distribution of three species of Liomijs in Jalisco, Mexico.
Closed circles indicate localities from which Liomijs spectabilis has been taken.
The inset map in the upper, left-hand corner indicates the position of the state

of Jalisco in western Mexico.

parts white; bacular morphology similar to that described for L.
pictus (Bm-t, 1960:44 and pi. 11).

Measurements. — External measurements (in millimeters) of the
male holot\'pe, followed by the mean (and extremes) of four adult
females for the first two measurements and eight for the second two
measurements are: total length, 280, 249.5 (242-261); length of tail,
142, 129.0 (122-134); length of hind foot, 31, 30.4 (29.5-32); length
of ear, 17, 16.9 (16.5-17.5). Weights of the holotype and another
adult male were respectively, 69.3 and 67.1 grams; seven nonpreg-
nant adult females averaged 51.2 (48.6-56.1) grams in weight.
Cranial measurements of tlie specimens of Liomijs spectabilis are
given in Table 1 along with comparative measrrrements of Liomys
pictus plantinarensis and Liomys pictus pictus.

NEW SPECIES OF SPINY POCKET MOUSE

B

C

Fig. 2. — Dorsal view of the crania of three taxa of Liomys: A. Liomijs pictus

pictus (KU 112276, c5 , San Sebastian, Jalisco); B. Liomys spcciahiUs (KU

96051, c$, 2.2 mi NE Contia, Jalisco); C. Liomys pictus planiinarensis (KU

96048, i , 2.2 mi NE Contia, Jalisco). Scale at right is 10 mm.

Comparisons. — From Liomys picttis plantinarensis witli which it
occurs sympatrically, Liomys spectahiJis can be distinguished easily
by its much larger size ( Table 1 ) . There is no overlap in measm-e-
ments of adults of the two taxa for total length, length of hind foot,
greatest length of skull, interorbital constriction, mastoid breadth,
length of nasals, and length of rostrum, and spectahiUs averages
significantly larger in all other measurements analyzed (Fig. 2).
Middorsal coloration of L. spectahiUs is significantly darker than
that of L. p. plantinarensis as revealed by use of a Photovolt Photo-
electric Reflection Meter, Model 610. Mean reflectance values for
L. spectahiUs, followed in parentheses by those for typical L. p.
plantinarensis, were: red, 11.0 (14.6); green, 6.3 (7.9); blue, 5.8
(7.1).

From Liomys pictus pictus of the coastal and montane areas of
western JaHsco, L. spectahiUs is again distinguished by its larger
size, although the difference is not as striking as in the case of
plantinarensis (Table 1, Fig. 2). Only in gi-eatest length of skull
and length of rostium is there no overlap in the measurements of the
two taxa, although spectahiUs averages larger in all measurements
except for interparietal length of females. A useful character in
separating these two taxa externally is length of the hind foot, which
is rarely less than 30 in spectahiUs and rarely more than 30 in pictus.
The only subspecies of L. pictus that approaches L. spectahiUs in
size is annectens from the mountains of Guerrero and Oaxaca. From
this race, spectahiUs can be distinguished by its slightly larger over-

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6 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

all size, proportionately shallower cranium, and paler dorsal
coloration.

Liomys spectahiJis can be distinguished from Liomys irroratus
jaliscensis from southeastern Jalisco by its generally longer but pro-
portionately narrower cranium (greatest length of irroratus males,
33.4, females, 31.8; mastoid breadth, 14.9 and 14.4). Other charac-
teristics distinguishing spectobilis from irroratus are those characters
that also serve to distinguish pictus from irroratus — for example,
differences in bacular morphology (Burt, 1960:44), six (spectabilis
and pictus) rather than fi\'e plantar tubercles on the hind feet, and
reddish brown dorsal coloration and a bright ochraceous lateral
stripe ( as compared to grayish brown coloration and a pale pinkish
lateral stripe in irroratus).

Remarks. — Liomys spectabilis appears to be a member of the
Liomys pictus-group as defined by Goldman (1911). L. spectabilis
occupies a restricted distribution near the eastern limits of the geo-
graphic range of L. pictus in Jalisco. It seems plausible that the
precursor of these two species occurred throughout this area of
Mexico, and that the parental stock was split into two parts in re-
sponse to changing environmental conditions. One segment prob-
ably was resti-icted to coastal regions of western Mexico and ga\'e
rise to L. pictus, whereas the other was isolated in interior Jalisco
and gave rise to L. spectabilis. Subsequent to speciation, L. pictus
has reinvaded inland areas of Jalisco and now occurs sympatrically
with spectabilis at several localities.

The area northeast of Contla, Jalisco, in the vicinity of the type
locality is under heavy agricultiu'al use. All trapping in this area was
conducted in the immediate vicinity of a high\\'ay which follows a
shallow valley northeastward from Contla. The road right-of-way is
about 40 to 50 feet wide at most points and has been allowed to
grow to weeds, low brush, and ti'ees; cornfields were present beyond
the right-of-way in relatively level areas. Around the edges of these
cornfields were rock or wire fences that were heavily overgrowai
with weeds and brush. On adjacent hillsides, where the slope be-
came too steep to plant corn the grass was heavily grazed in most
places and was interspersed with clumps of dense, low brush. It was
along fencerows and in pastureland of the type described that P. L.
Clifton obtained the original series of the new species between 17
and 27 September 1963. During that period Clifton obtained speci-
mens of Liomys spectabilis and Liomys pictus plantinarensis in the
same traplines at three localities as follows: 3.3 mi NE Contla (four
spectabilis and two pluntimirensis), 3 mi NE Contla (one spectabilis

NEW SPECIES OF SPINY POCKET MOUSE 7

and one plantinarensis) , 2.2 mi NE Contla (seven spectabilis and 11
plant inarensis) . Along with Larry C. Watkins and Elmer C. Birney,
I revisited this same area on 7 August 1969 and obtained a specimen
of L. spectabilis at a place 6 km NE Contla, at the edge of a dense
clump of brush in a pasture. In early March 1964, P. L. Clifton
trapped three additional specimens of spectabilis 8/2 mi S Mazamitla.
Traps in which these specimens were taken were set along a brush
fence between a cornfield and a grove of oak. Nothing is known of
the circumstances under which the specimens from near Tecalitlan
and Pihuano were taken.

Only one of the six adult females of spectabilis evinced gross
reproductive activity; a female taken on 26 September 1963 at a
place 2.2 mi NE Contla carried five embryos that measured 4 mm in
crown-rump length. Four adult males taken between 17 and 20
September 1963 had testes that averaged 21.5 (21-22) in length.

Specimens examined (21). — All localities are in Jalisco (those in italics are
not plotted on Fig. 1 because undue crowding of symbols would have resulted):
8)2 mi S Mazamitla, 5300 ft, 3 ( KU 97182-84); 8 km N Contla, 4300 ft, 3 (KU
96035-37); 6 km NE Contla, 1310 m, 1 ( KU 120606); 3.3 mi NE Contla, 3900
ft, 4 (KU 96042-45); 3 mi NE Contla, 3850 ft, 1 (KU 96039); 2.2 mi NE
Contla, 3850 ft, 7 (KU 96049-54, 96064); 12 mi NE Pihuano, 3150 ft, 1 (Mich-
igan State University, 11496); 8 mi SW Tecalitlan, 1 (California Academy of
Science, 13961).

LITERATURE CITED

BUHT, W. H.

1960. Bacula of North American mammals. Misc. Publ. Mus. Zool., Univ.
Michigan, 113:1-76.
Goldman, E. A.

1911. Revision of the spiny pocket mice (genera Heteromys and Liomys).
N.Amer. Fauna, 34:1-70.

University of Kansas Publications
MUSEUM OF NATURAL HISTORY

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