University of Kansas Publications Museum of Natural History

Volume 14, No. 12, pp. 145-159, 1 fig. in text

May 18, 1962

Noteworthy Mammals from Sinaloa, Mexico

J. KNOX JONES, JR., TICUL ALVAREZ, AND M. RAYMOND LEE

University of Kansas


Lawrence


1962

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.

Volume 14, No. 12, pp. 145-159, 1 fig. in text


Published May 18, 1962

University of Kansas


Lawrence, Kansas

PRINTED BY


JEAN M. NEIBARGER, STATE PRINTER


TOPEKA, KANSAS

1962

29-3000

Noteworthy Mammals from Sinaloa, Mexico

BY

J. KNOX JONES, JR., TICUL ALVAREZ, and M. RAYMOND LEE

In several of the past twelve years field parties from the Museum
of Natural History have collected mammals in the Mexican state of
Sinaloa. Most of the collections contained only a modest number
of specimens because they were made by groups that stopped for
short periods on their way to or from other areas, but several collections
are extensive. Field work by representatives of this institution
now is underway in Sinaloa with the aim of acquiring materials
suitable for treating the entire mammalian fauna of that state.

Among the mammals thus far obtained are specimens of twenty
species that represent significant extensions of known range, are of
especial taxonomic or zoogeographic interest, or that complement
published information, and it is these records that are reported
herein.

The following persons obtained specimens mentioned beyond:
J. R. Alcorn (1950); J. R. and A. A. Alcorn (1954 and 1955); R. H.
Baker and a party of students (1955); W. L. Cutter (1957); S. Anderson
and a party of students (1959); M. R. Lee (1960 and 1961);
and J. K. Jones, Jr., accompanied by R. R. Patterson and R. G.
Webb (1961). The Kansas University Endowment Association and
the American Heart Association provided funds that helped to defray
the cost of field operations.

In the accounts that follow, all measurements are in millimeters
and all catalogue numbers refer to the mammal collection of the
Museum of Natural History, The University of Kansas. Placenames
associated with specimens examined are indicated on the
accompanying map (Fig. 1).

Notiosorex crawfordi (Coues).—A non-pregnant female (75184)
was obtained on November 29, 1957, at El Fuerte by W. L.
Cutter. Comparison of this specimen with topotypes of N. evotis
(see below) and with undoubted examples of N. crawfordi proves
our specimen to be referable to the latter. We presume that the
shrew reported as evotis on geographic grounds from El Carrizo
by Hooper (1961:120) also is referable to crawfordi. External
measurements of our female are: total length, 77; length of tail, 20
(tip missing); length of hind foot, 11; length of ear from notch, 8;
weight in grams, 4. Cranial measurements of this individual are
given in Table 1.

Fig. 1. Map of Sinaloa on which are plotted symbols representing placenames
mentioned in text. From north to south, these are: El Fuerte; San
Miguel; Los Mochis; Guamúchil; Terrero; Pericos; Culiacán; El Dorado;
Piaxtla and Camino Reál (one symbol); Pánuco; Mazatlán; Matatán; Rosario;
Escuinapa; Concepción.

Notiosorex evotis (Coues).—Four topotypes (85533-36), all
males, were collected by Lee at Mazatlán. One was caught on December
17, 1960, in a museum special trap set "in low weeds near
thorn bush" in a sandy field at the north edge of Mazatlán, less than
a mile from the ocean. A few trees and some grasses grew in this
area; Mus musculus and Perognathus pernix were taken in the same
line of traps. Additional trapping at this locality failed to produce
more shrews. The other three specimens were captured alive on
February 1 (one) and February 2 (two), 1961, in the wake of a
bulldozer that was clearing land adjacent to the place where the
first specimen was trapped. The ground cover being cleared away
consisted mostly of dry, dense weeds and short, thorny scrub; the
latter was sparse in some places and formed dense thickets in others.
One individual that was kept alive for a short time in a can ate
crickets and roaches readily and ate one spider, but refused isopods.
On one occasion it ate six crickets in about three hours. Wet oatmeal
and oatmeal mixed with peanut butter both were refused.

Table 1. Cranial Measurements of Two Species of Notiosorex.

Average and extreme external measurements of the four males are as follows:
total length, 93.2 (90-98); length of tail, 25.5 (23-27); length of hind
foot, 11.9 (11-13); length of ear from notch, 7.7 (7-8); weight in grams, 5.4
(4.4-6.3). Cranial measurements are given in Table 1.

Notiosorex evotis was described by Coues (1877:652) on the basis
of a single specimen, obtained at Mazatlán by Ferdinand Bischoff
in 1868, that originally had at least the partial skull inside. Subsequently
the skull was removed and evidently lost (Poole and
Schantz, 1942:181). Coues named evotis as a species distinct from
crawfordi (described by him in the same paper) on the basis of
larger size, shorter tail, and alleged slight differences in color. He
did not describe the skull, but did note that the dentition was "substantially
the same as that of N. crawfordi." Evidently, the only
other correctly identified specimen of evotis on record is an individual
from Mazatlán in the British Museum, the skull of which
was figured by Dobson (1890:pl. 23, fig. 20).

Merriam (1895:34) characterized evotis, known to him by only
the holotype, as: "Similar to N. crawfordi, but slightly larger and
darker." He did not examine the skull, which by that time had
been "lost or mislaid." Merriam reduced evotis to subspecific status
under crawfordi with the following remarks: "In the absence of
sufficient material of N. evotis, it is impossible to determine its exact
relations to crawfordi. Dobson did not recognize it as distinct, but
figured its teeth under the name crawfordi [loc. cit., possibly a
lapsus]. For the present it seems best to retain it as a subspecies."

Merriam's arrangement of evotis as a subspecies of crawfordi has
been followed by subsequent workers, mostly, we suppose, because
additional material of undoubted evotis has not until now been
available. Comparisons of our four specimens with specimens
(from Jalisco, Sinaloa and Tamaulipas) and published descriptions
and measurements (see especially Hoffmeister and Goodpaster,
1954:46-47, 51) of crawfordi reveal that evotis has a longer body
and hind foot than crawfordi but a relatively (sometimes actually)
shorter tail and ear, and a distinctly larger, heavier skull (see Table
1). The upper parts of our specimens average pale brownish
gray and are paler, not darker, than the upper parts of crawfordi.
But, all of the latter were obtained in the warm months of the year
except one November-taken individual from El Fuerte, Sinaloa, the
dorsal pelage of which approaches in color that of the darkest of
the evotis. The pelage of both kinds probably is paler in winter
than in summer and may be indistinguishable in the same season.
Ventrally, all four evotis are grayish white, faintly to moderately
tinged with brownish buff.

Notiosorex evotis differs cranially from Notiosorex crawfordi as
follows: larger (see measurements); mesopterygoid fossa squared
rather than broadly U-shaped anteriorly; rounded process on maxillary
at posterior border of infraorbital canal well developed (faint
or lacking in crawfordi); occipital condyles smaller and, in lateral
view, elevated above basal plane of skull; upper molars slightly
more crowded in occlusal view. These differences, although admittedly
slight, appear to be constant in the specimens we have
seen, but ought to be used cautiously owing to the small samples
studied.

Shrews of the genus Notiosorex have been reported twice previously
from localities in west-central México, other than from Mazatlán,
as follows: 21 mi. SW Guadalajara (remains from owl pellets)
and 13 mi. S, 15 mi. W Guadalajara, Jalisco, by Twente and
Baker (1951:120-121); and Cerrito Loco, 2 mi. E La Palma, Michoacán
(remains from owl pellets), by Baker and Alcorn (1953:116).
The remains were referred to evotis on geographic grounds in one
instance and were so referred inferentially in the other. Examination
of the specimens upon which these reports were based reveals
that all are crawfordi on the basis of characters previously cited. As
a result, N. evotis is known only from the type locality at Mazatlán,
whereas N. crawfordi is widely distributed on the Mexican Plateau
as far south as Jalisco and northern Michoacán, and occurs on the
west side of the Sierra Occidental as far south as northern Sinaloa.

The two kinds obviously are closely related and intergradation
eventually may be demonstrated between them. But, for the present,
we adopt a conservative course and treat evotis as a full species
owing to its distinctive features, restricted geographic distribution,
and the lack of evidence of intergradation between it and crawfordi.

Balantiopteryx plicata pallida Burt.—Thirty-five specimens from
two adjacent localities along the Río del Fuerte in northern Sinaloa,
3 mi. NE San Miguel, 300 ft. (84944-48) and 10 mi. NNE Los Mochis
(60572-75, 60667-78, 60681-94), provide the first records of the
subspecies from the state. Individuals from both localities were
shot at dusk as they foraged among trees in the valley of the river.
Fifteen of 18 females from 10 mi. NNE Los Mochis, collected on
June 5, 6 and 7, 1955, were pregnant; each contained a single embryo,
the embryos ranging from 7 to 15 mm. in crown-rump length.
B. p. pallida previously has been reported from the southern parts
of Baja California and Sonora.

Balantiopteryx plicata plicata Peters.—Specimens in the Museum
of Natural History from the following localities, several of which
are marginal, document better than previously has been done the
distribution of this subspecies in Sinaloa: 32 mi. SSE Culiacán
(60699); 10 mi. SE Escuinapa (68629); 17 mi. SSE Guamúchil
(60576); 5 mi. NW Mazatlán (85537-61, 85901-04); 1 mi. SE Mazatlán,
10 ft. (39461-76); 1 mi. S Pericos (60697-98, 60700); ½ mi. E
Piaxtla (60701); ½ mi. W Rosario, 100 ft. (39477-79); 5 mi. SSE
Rosario (60702-03); 4 mi. N Terrero (60695-96).

Pregnant females, each with a single embryo, were recorded in
1954 from 4 mi. N Terrero, 2 (June 9), 1 mi. S Pericos, 2 (June 13),
and 5 mi. SSE Rosario, 2 (June 20). None of 16 December-taken
females from 5 mi. NW Mazatlán was pregnant.

The specimen from 17 mi. SSE Guamúchil, preserved in alcohol,
is provisionally referred to B. p. plicata on geographic grounds inasmuch
as specimens from the nearby localities of 1 mi. S Pericos
and 4 mi. N Terrero, although more grayish on the average than
specimens from southern Sinaloa, are somewhat darker and distinctly
larger than specimens of B. p. pallida from along the Río del
Fuerte in northern Sinaloa. Specimens from southern Sinaloa
average only slightly paler than typical plicata examined from
southern México and Nicaragua.

Pteronotus psilotis (Dobson).—A total of six specimens from two
localities in southern Sinaloa provide the first records from the state
and are the northernmost records in western México. The two localities
are: ½ mi. S Concepción, 250 ft. (84987-90); 1 mi. W Matatán
(84985-86). The two individuals from the last-mentioned place
extend the known range of the species approximately 275 miles
north-northwest from a locality 7 mi. W, ½ mi. S Santiago, Colima
(Anderson, 1956:349), and place the limit of the known distribution
of P. psilotis farther to the north in western México than in the eastern
part of the country. We follow Burt and Stirton (1961:24-25)
in use of the generic name Pteronotus for this species.

The two specimens from 1 mi. W Matatán were shot at late dusk
as they foraged with other bats, presumably of the same species, low
over water at the place where the Río San Antonio joins the larger
Río Baluarte. The four individuals from ½ mi. S Concepción were
captured in mist nets stretched across the Río de las Cañas at the
Sinaloa-Nayarit border, and were taken shortly after dark at heights
of three feet or less above the water. Our six specimens all are
males. Five are in the reddish color phase and one is in the brownish
phase.

Average and extreme measurements of the six males, which average slightly
smaller than specimens examined from Colima and Guerrero, are as follows:
total length, 66.8 (65-69); length of tail, 16.3 (15-18); length of hind foot,
11.8 (11-12); length of ear from notch, 16.9 (16.5-17.0); length of forearm
(dry), 41.5 (40.6-42.4); weight in grams, 8.3 (6.9-9.8); greatest length of
skull, 15.4 (15.2-15.5); zygomatic breadth, 8.3 (8.2-8.4); interorbital constriction,
3.4 (3.3-3.6); mastoid breadth, 8.7 (8.6-8.8); length of maxillary tooth-row,
5.8 (5.8-5.9); breadth across M3, 5.4 (5.3-5.6).

Sturnira lilium parvidens Goldman.—The first specimens to be
reported from Sinaloa are as follows: 32 mi. SSE Culiacán (61087);
1 mi. S El Dorado (75207); Pánuco, 22 km. NE Concordia (85648-50).
The three bats from the last-mentioned locality were caught
after midnight in a mist net stretched across a road adjacent to a
nearly dry stream bed. The vegetation in the vicinity of the net
consisted mostly of dry weeds and grass along with some low shrubs,
but a tree-filled canyon was about one-fourth mile above the net.
We lack details about the capture of the other two bats.

S. l. parvidens has been reported only once from farther north in
western México than Sinaloa. Anderson (1960:7) recorded five
specimens from along the Río Septentrión, 1½ mi. SW Tocuina, Chihuahua.

Artibeus lituratus palmarum Allen and Chapman.—This species
has been reported once previously from Sinaloa (from 1 mi. S El
Dorado by Anderson, 1960:3). Six specimens (85668-72, 85674),
all males, collected on December 23 and 24, 1960, at Pánuco, 22 km.
NE Concordia, provide the second known occurrence in the state.

Artibeus toltecus (Saussure).—A male (85666) from Pánuco, 22
km. NE Concordia, provides the first record of this species from
Sinaloa and extends the known range northwestward approximately
182 miles from Ambas Aguas [= 6½ km. SW Amatlán de Jora],
Nayarit (Andersen, 1908:300). Our specimen was taken on December
22, 1960, in a mist net placed across a road in an area where
vegetation consisted mostly of weeds, grasses and shrubs. Two
Glossophaga soricina leachii and two Choeronycteris mexicana were
taken in the same net.

Davis' (1958:165-166) key is useful in separating the small Mexican
members of the genus Artibeus, but we have found some adults
of toltecus to be smaller than the key indicates. For example, in the
12 Mexican specimens (Oaxaca, 6, Tamaulipas, 3, Jalisco, 2, Sinaloa,
1) examined by us the total length of skull varies from 19.7 to
21.0 and the forearm from 36.3 to 42.6.

Dalquest (1953) and more recently Koopman (1961) regarded
A. toltecus and the larger A. aztecus, which occurs in the same areas
but at higher elevations than toltecus, as subspecies of the more
southerly A. cinereus. Davis (op. cit.), on the other hand, recognized
toltecus, aztecus, and cinereus as distinct species. More specimens
of small and medium-sized Artibeus are needed from México
before this baffling complex can be studied adequately, but on the
basis of specimens examined we are inclined to agree with Davis
as concerns the specific distinctness of toltecus and aztecus. In
Tamaulipas (the mammalian fauna of which is currently under
study by Alvarez) for example, toltecus is known from Rancho
Pano Ayuctle at an elevation of 300 feet in tropical deciduous forest,
whereas aztecus has been taken only four miles away at Rancho del
Cielo, but at an elevation of 3000 feet in cloud forest. The altitudinal
difference between ranges of the two kinds in Tamaulipas corresponds
to that found in Sinaloa (see Koopman, loc. cit.) and is
of approximately the same magnitude found by Davis at higher elevations
in Guerrero. This relationship suggests that the two kinds
are neither subspecies of a single species, nor individual variants
of a widespread, monotypic species, but probably are two different
species. We agree that one, most likely the smaller toltecus, may
eventually prove to be a northern subspecies of cinereus.

Myotis occultus Hollister.—A single specimen of this species
(67491) from 1 mi. N, ½ mi. E San Miguel provides the first certain
record from Sinaloa, and is indistinguishable from specimens from
Alamos, Sonora, that were referred to occultus by Hall and Dalquest
(1950:587). Miller and Allen (1928:100) identified a skin alone
from Escuinapa as occultus, but Hall and Dalquest (loc. cit.) later
assigned this specimen provisionally to M. fortidens on geographic
grounds and because it agreed in color with undoubted specimens
of the latter from Guerrero. Specimens from south of San Miguel
and north of the undoubted range of fortidens are needed in order
to ascertain whether the two kinds are distinct species or instead
only subspecies of a single species.

The Sinaloan bat was taken in a mist net stretched over a drainage
ditch adjacent to the Río del Fuerte on the night of June 19-20,
1955, by R. H. Baker. Several other kinds of bats were obtained
(shot or netted) at the same place, among which was one specimen
of Myotis velifer. The specimens studied of occultus from Sinaloa
and Sonora are clearly separable from specimens of velifer from the
same region (Sonora and northern Sinaloa) in having paler (more
reddish) pelage, shorter forearm, smaller skull, relatively broader
rostrum, and four fewer teeth.

Myotis velifer velifer (J. A. Allen).—Three specimens from the
following localities in northern Sinaloa provide the first records of
the species from the state: El Fuerte (75234); Río del Fuerte, 1
mi. N, ½ mi. E San Miguel (67490); Río del Fuerte, 10 mi. NNW
Los Mochis (61149). The subspecies M. v. velifer has been reported
previously from the adjacent states of Chihuahua, Durango,
and Sonora.

A female (61149) obtained on June 8, 1954, carried a single embryo
that measured 3 mm. in crown-rump length.

Lasiurus borealis teliotis (H. Allen).—A female from 10 mi.
NNW Los Mochis (61172), obtained on June 8, 1954, represents
the first record of the species from Sinaloa, and is tentatively referred
to this subspecies. It resembles cranially, but is paler than,
Californian specimens seen of teliotis.

Molossus ater nigricans Miller.—This large free-tailed bat previously
has been reported no farther north in western México than
the type locality, Acaponeta, Nayarit. Nineteen specimens from
four different localities in Sinaloa are as follows: 1 mi. SE Camino
Reál, 400 ft. (85093-99); 32 mi. SSE Culiacán (61279-87); 1 mi. S
Pericos (61277-78); ½ mi. E Piaxtla (61288). The specimens labeled
with reference to Camino Reál and Piaxtla were obtained
along the Río Piaxtla at approximately the same place. Those from
1 mi. S Pericos extend the known range of the species approximately
225 miles northwestward.

M. a. nigricans is characteristically an early flier. Along the Río
Piaxtla, 1 mi. SE Camino Reál, where bats probably found daytime
retreats in the rocky walls of the steep-sided valley of the river, individuals
first appeared early in the evening when the sun was still
on the western horizon, but were gone before other species of bats
were seen. A female from 32 mi. SSE Culiacán, taken on June 18,
1954, contained one embryo that was 18 mm. in crown-rump length.
Each of the color phases of the species, reddish (8) and black (11),
are represented among our specimens. We follow Goodwin (1960)
in the use of the specific name ater for this bat.

Dasypus novemcinctus mexicanus Peters.—Two armadillos
(85402-03) from the valley of the Río del Fuerte, 3 mi. NE San
Miguel, 300 ft., are the first of the species to be reported from
northern Sinaloa. They extend the known range northwestward in
the state approximately 285 miles from Escuinapa (Russell, 1953:25)
and signal the possible occurrence of D. n. mexicanus in southern
Sonora. Sign of the armadillo was abundant at the place where
our two specimens were collected. Because it was felt that the
species possibly had been introduced along the Río del Fuerte, a
number of local residents were questioned on the point, but all insisted
that armadillos were native to the area.

External measurements of 85402 (female) and 85403 (male) are, respectively,
as follows: total length, 725, 748; length of tail, 351, 357; length of
hind foot, 87, 89; length of ear from notch, 39, 39.

Sylvilagus audubonii goldmani (Nelson).—This cottontail has
been reported from Sinaloa only from Bacubirito, Culiacán (type
locality), and Sinaloa (Nelson, 1909:226). Additional records are:
12 mi. N Culiacán (67561-62); 6 mi. N El Dorado (75263); 6 mi. N,
1½ mi. E El Dorado (75264-66); 7 mi. NE El Fuerte (81076-77); and
1 mi. S Pericos (61292-93). Specimens from the vicinity of El Dorado
extend the known range some 30 miles southward from the
type locality. A female from 1 mi. S Pericos that was taken on
June 13, 1954, carried three embryos that measured 29 mm. in
crown-rump length.

Sciurus truei Nelson.—Three specimens (61300-02) of this species
collected by A. A. Alcorn on June 19, 1954, 32 mi. SSE Culiacán
extend the known range approximately 210 miles south-southeast
from Guirocoba, Sonora (Burt, 1938:38), and provide the first record
from Sinaloa. Two of the specimens are females and each was
pregnant, one with two embryos and the other with three.

Our specimens generally agree in color with S. truei, but are
larger than typical individuals and in this respect approach S. sinaloensis
of southern Sinaloa. Probably truei and sinaloensis both are
only subspecies of the more southerly S. colliaei. The three nominal
species currently constitute the S. colliaei group in which the presence
or absence of P3 seems to vary geographically. The tooth frequently
is absent in the northern truei and usually present (invariably
in the specimens we have examined) in colliaei. Only one of
our Sinaloan specimens is accompanied by a skull; in it P3 is present
on the right side and absent on the left.

External measurements of the male and two females are, respectively: total
length, 512, 508, 504; length of tail, 263, 263, 252; length of hind foot, 64, 63,
64; length of ear from notch, 28, 29, 28. Cranial measurements of 61300 (a
female) are: greatest length of skull, 56.2; zygomatic breadth, 32.6; interorbital
constriction, 17.9; postorbital constriction, 17.9; length of nasals, 17.3;
alveolar length of maxillary tooth-row (on side lacking P3), 10.9.

Thomomys umbrinus atrovarius J. A. Allen.—Two specimens
(85104-05) from the valley of the Río Piaxtla, 1 mi. SE Camino
Reál, 400 ft., resemble the description of atrovarius and agree in
size, color and most cranial details with a specimen (85744) from
5 mi. NW Mazatlán. The first-mentioned specimens extend the
known range of the subspecies some 50 miles northward from Mazatlán
(Bailey, 1915:96), and indicate the probable occurrence of
the species at lower elevations in other parts of central Sinaloa.

Peromyscus merriami goldmani Osgood.—This subspecies has
been reported previously only from the type locality, Alamos, Sonora.
Eight specimens were collected in Sinaloa by W. L. Cutter
in the autumn of 1957 as follows: 6 mi. N, 1½ mi. E El Dorado
(75368-72); 2½ mi. N El Fuerte (75365-66); El Fuerte (75367).
The first-mentional locality is approximately 200 miles south-south-east
of the type locality. All specimens collected by Cutter were
taken in lowland areas, supporting remarks by Commissaris (1960)
concerning habitat preferences of P. merriami as compared with
those of the closely related P. eremicus.

Two of three females from northeast of El Dorado were pregnant
on November 18 and 19; one carried four embryos (8 mm. in crown-rump
length) and the other three (11 mm.).

External and cranial measurements of P. m. goldmani previously were
known only for the holotype (Osgood, 1909:252, 267). Measurements of
five adults, a male (75370) and four females (75365, 75369, 75371-72) are,
respectively, as follows: total length, 204, 225, 215, 214, 210; length of tail,
105, 120, 110, 108, 109; length of hind foot, 21, 23, 23, 22, 22; length of ear
from notch, 21, 21, 21, 20, 21; weight in grams, 29, 19, 35 (pregnant), 33, 34
(pregnant); greatest length of skull, 26.6, 26.5, 26.9, 26.5,——; zygomatic
breadth, 13.8, 13.9, 14.1, 13.4,——; interorbital constriction, 3.9, 3.8, 4.0,
4.0,——; mastoid breadth, 11.8, 11.9, 11.8, 11.9, 11.5; length of nasals, 10.1,
9.4, 10.0, 10.0,——; length of maxillary tooth-row, 4.5, 4.3, 4.1, 4.1, 4.1.

Onychomys torridus yakiensis Merriam.—Only one specimen of
this grasshopper mouse has been reported previously from Sinaloa
(from the town of Sinaloa by Hollister, 1914:471). Thirteen specimens
in the Museum of Natural History better define the range of
the species in the state as follows: 12 mi. N Culiacán (67981-82); 6
mi. N, 1½ mi. E El Dorado (75374-80); 2½ mi. N El Fuerte (75373);
1 mi. S Pericos (62118-20). The individuals from northeast of El
Dorado extend the known range of the species some 115 miles south-southeast
from Sinaloa.

A female taken on November 17, 1957, from 6 mi. N, 1½ mi. E El
Dorado carried two embryos that measured 23 mm. in crown-rump
length. A female obtained on November 18 at the same place carried
four embryos that measured 10 mm.

Neotoma albigula melanura Merriam.—Four specimens from
northern Sinaloa, two (85379-80) from 3 mi. N, 1 mi. E San Miguel,
350 ft., and two (75386-87) from 2½ mi. N El Fuerte, provide the
first records of the species from the state. N. a. melanura has been
known previously from adjacent parts of Sonora and Chihuahua
(see Hall and Kelson, 1959:687-688). The specimens from northeast
of San Miguel were trapped in runways under cholla cactus,
in which nests also were found, on a slope above a rocky arroyo.

Spilogale pygmaea Thomas.—Two pygmy spotted skunks from
5 mi. NW Mazatlán (85898-99) are the fifth and sixth of the species
to be reported (see Van Gelder, 1959:381) and the second and third
taken in Sinaloa (the holotype of pygmaea was obtained at Rosario).
One of our specimens, an adult male, was shot on the night
of January 10, 1961, as it foraged near an old hollow tree in weedy-thorn
bush habitat adjacent to the Pacific Ocean. The hollow tree
contained the nest of a woodrat. The second, an adult female, was
trapped nearby in a commercial rat trap baited with peanut butter
and set near a burrow in a forested area having little undergrowth.

The two individuals here reported fit fairly well the description of color
pattern given for the species by Van Gelder (op. cit.: 379), but are larger
(considering sex), externally and cranially, than any of the four specimens reported
previously. Measurements of the male and female are, respectively:
total length, 291, 270; length of tail, 65, 58; length of hind foot, 38, 35; length
of ear from notch, 25, 23; weight in grams, 247.0, 190.5; condylobasal length,
46.0, 42.9; occipitonasal length, 45.0, 41.4; zygomatic breadth, 29.0, 27.3;
mastoid breadth, 23.9, 22.5; interorbital constriction, 14.3, 13.6; postorbital
constriction, 14.8, 14.1; palatilar length, 15.6, 14.6; postpalatal length, 23.2,
22.4; cranial depth, 16.6, 15.2; length of maxillary tooth-row, 14.2, 13.4.
Cranial measurements were taken in the manner described by Van Gelder
(op. cit.: 236-237).

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Transmitted March 15, 1962.

29-3000

Transcriber's Notes

Corrected typo: semi-colon for comma in "postpalatal length, 23.2, 22.4;".