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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY

Volume 9, No. 18, pp. 513-518, 1 map
January 14, 1960



Conspecificity of two pocket mice,
Perognathus goldmani and P. artus


BY

E. RAYMOND HALL AND MARILYN BAILEY OGILVIE



UNIVERSITY OF KANSAS
LAWRENCE
1960




UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson


Volume 9, No. 18, pp. 513-518, 1 map
Published January 14, 1960


UNIVERSITY OF KANSAS
Lawrence, Kansas


PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1960

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Conspecificity of two pocket mice, Perognathus goldmani and P. artus

BY

E. RAYMOND HALL AND MARILYN BAILEY OGILVIE


_Perognathus goldmani_ Osgood and _Perognathus artus_ Osgood from
southern Sonora, northern Sinaloa and adjoining parts of Chihuahua and
Durango, are two named kinds of the _Perognathus intermedius_ group of
pocket mice, of the subgenus _Chaetodipus_. Until now the two kinds
have been treated in the literature as two species. In both _goldmani_
and _artus_ the upper parts are Ochraceous-Buff (capitalized color
terms after Ridgway, Color Standards and Color Nomenclature,
Washington, D. C., 1912) having a strong admixture of black. The
lateral line is Ochraceous-Buff, and the underparts are white. _P.
goldmani_ is larger than _P. artus_ (see measurements beyond) and has
more inflated tympanic bullae and a relatively narrower (transverse to
long axis of skull) interparietal bone.

Specimens from a transect of southeastern Sonora show intergradation
between _Perognathus goldmani_ and _P. artus_. From northwest to
southeast the specimens are as follows: one mile east of Buena Vista,
on Río Yaqui Reservoir, 1000 feet (2 specimens, K. U.); Alamos, 1200
feet (7, U. S. B. S.); four and a half miles southeast of Alamos, 1000
feet (5, K. U.); nine miles southeast Alamos, 1000 feet (5, K. U.). The
specimens (_P. goldmani_) from Río Yaqui Reservoir are largest. Those
from nine miles southeast of Alamos (_P. artus_) are smallest. Those
from Alamos proper are _P. goldmani_. Those from four and a half miles
southeast of Alamos (80051-80055 K. U. collected by Robert L. Packard
and here referred to _goldmani_) include two as large as _goldmani_
from Alamos, one as small as _artus_ from nine miles southeast of
Alamos, and two that are intermediate in size. Features other than
size, considered geographically, also suggest intergradation.

Six specimens (61409-61413, 61415 K. U. collected by J. R. Alcorn),
including five adults (permanent fourth premolar of full height and
having cusps worn but not so much as to make a lake of dentine), from
four miles north of Terrero, Sinaloa, also seem to be intergrades
between _Perognathus goldmani_ and _Perognathus artus_. As compared
with adults of _P. goldmani_ from 10 miles north-northwest of Los
Mochis, Sinaloa, and _P. artus_ from one mile south of Pericos,
Sinaloa, the specimens from four miles north of Terrero are almost
exactly intermediate in length of hind foot, width of interparietal,
and width of tympanic bullae. Intermediacy is shown also in total
length of animal (slightly nearer that of _artus_) and length of
tympanic bullae (slightly nearer that of _goldmani_). In lack of
inflation laterally of the mastoidal bullae the specimens agree with
_artus_. In occipitonasal length and mastoidal breadth the specimens
from four miles north of Terrero average even larger than _goldmani_
from 10 miles north-northwest of Los Mochis but not so large as
specimens of _goldmani_ from the type locality, which is still farther
north. The uninflated mastoidal bullae "tip the balance" slightly in
favor of _artus_ to which the specimens from four miles north of
Terrero are here referred. The degree of inflation of the mastoidal
bullae elsewhere varies geographically. For example, the mastoidal
bullae of the 25 specimens of _goldmani_ from two and a half miles
north of El Fuerte, Sinaloa, are intermediate in size as between those
of _goldmani_ and _artus_.

The morphological intermediacy of the specimens from four and a half
miles southeast of Alamos and of those from four miles north of
Terrero, along with the geographic intermediacy of the two localities
where the specimens were obtained constitute basis for arranging
_artus_ as a subspecies of _goldmani_ that has one page of priority.

[Illustration: MAP 1. Geographic distribution of _Perognathus
goldmani_. The black dots are known localities of occurrence.

1. _P. g. artus_

2. _P. g. goldmani_]


~Perognathus goldmani goldmani~ Osgood

     _Perognathus goldmani_ Osgood, N. Amer. Fauna, 18:54,
     September 20, 1900, type from Sinaloa, Sinaloa.

     _Range._--See map 1.

     _Measurements._--Average of five topotypes (Osgood, _op.
     cit._:55): total length, 202; tail vertebrae, 112; hind
     foot, 28; occipitonasal length, 27.7; mastoidal breadth,
     14.5; greatest width of interparietal, 7.4.

     _Records of occurrence_ (in each state the localities are
     listed from north to south).--Sinaloa: 2-1/2 mi. N El
     Fuerte, 25 K. U.; Sinaloa (Osgood, N. Amer. Fauna, 18:55,
     September 20, 1900); 10 mi. NNW Los Mochis, 18 K. U. Sonora:
     1 mi. E Buena Vista, on Río Yaqui Reservoir, 1000 ft., 2 K.
     U.; Camoa, 7 (U. S. N. M.); Tesia (Burt, Miscl. Publ. Mus.
     Zool., Univ. Michigan, 39:46, February 15, 1938); Alamos, 7
     (U. S. N. M.); 4-1/2 mi. SE Alamos, 1000 ft., 5 K. U.;
     Chinobampo (Burt, _loc. cit._); 3 mi. NNW Bacarachi
     [= Bacavachi], 2 K. U.


~Perognathus goldmani artus~ Osgood

     _Perognathus artus_ Osgood, N. Amer. Fauna, 18:55, September
     20, 1900, type from Batopilas, Chihuahua.

     _Range._--See map 1.

     _Measurements._--Average of five adult topotypes (Osgood,
     _op. cit._:55, 63): total length, 191; tail vertebrae, 106;
     hind foot, 24.6; occipitonasal length, 25.4; mastoidal
     breadth, 12.4; greatest width of interparietal, 7.1.

_Remarks._--Considerable individual variation has been noted in each of
several populations of _Perognathus goldmani artus_. For example, in 14
adults from Culiacán, Sinaloa, the variation is 25.0 to 27.9 in
occipitonasal length and in mastoidal breadth is 12.6 to 14.0. Ten
specimens (83122-83131 Univ. Mich.) labeled as from Carimechi, Río
Mayo, Chi[huahua], were recorded by Burt and Hooper (Occas. Papers Mus.
Zool., Univ. Michigan, 430:6, May 27, 1941) as from "near Carimechi."
They identified the two largest (83130 and 83131) as _Perognathus
goldmani_ and the others as _Perognathus artus_. These identifications
were reasonable in the light of knowledge available in 1941, but in the
light of information presently available from the now more abundant
material it is clear that all 10 of the specimens are _P. g. artus_.
Examination (by Hall) of the specimens reveals that the differences
relied upon by Burt and Hooper to differentiate the two species are
well within the range of individual variation. For example, the
variation (5.3 to 5.6 mm.) in width of the supraoccipital is less than
in each of some other series of specimens of equal age of _P. g. artus_
from other localities.

Also, there is geographic variation in the mice here assigned to the
subspecies _P. g. artus_; skulls are smaller in the northern part of
the geographic range and become gradually larger toward the south. In
five adults from the northern part (Batopilas 3, and 26 mi. NE Choix 2)
the mean of 12.6 of the mastoidal breadth of the skull is significantly
smaller than the corresponding mean of 13.3 in 21 adults from the
southern part (32 mi. SSE Culiacán 14, and El Dorado 7). The pelage of
individuals from one and a half miles southwest of Tocuina is notably
dark both above and below; the venter is dusky rather than white. We
suppose that the darker color is a response to a dark-colored
substrate--lava and soils derived from dark lava.

     _Records of occurrence_ (in each state the localities are
     listed from north to south).--Chihuahua: Carimechi, Río
     Mayo, 10 U. Mich.; 1-1/2 mi. SW Tocuina [Tocuina is a
     construction camp, in 1959, on NW bank of the Río
     Septentrión, and is not the Tacuina shown on some maps SE of
     that River], 10 K. U.; Batopilas, 6 U. S. N. M. Durango:
     Chacala (Osgood, N. Amer. Fauna, 18:55, September 20, 1900).
     Sinaloa: Rancho Rosalita, 26 mi. NE Choix, 3 K. U.; 4 mi. NE
     Terrero, 6 K. U.; 1 mi. S Pericos, 20 K. U.; 12 mi. N
     Culiacán, 29 K. U.; 32 mi. SSE Culiacán, 20 K. U.; 6 mi. N,
     1/2 mi. E El Dorado, 41 K. U.; El Dorado, 2 K. U. Sonora:
     Río "Cuchahaque," 11.3 mi. E Alamos, 5 Univ. Arizona; 9 mi.
     SE Alamos, 1000 ft., 5 K. U.

We have not seen any specimens that are intergrades between _P.
goldmani_ and _Perognathus intermedius_ (subspecies _intermedius_ or
_lithophilus_), nor between _P. goldmani_ and _Perognathus nelsoni_
(subspecies _nelsoni_ or _canescens_), nor between _P. intermedius_ and
_P. nelsoni_. Collecting and studying specimens from geographically
appropriate places to test for intergradation between these three
species would be worthwhile as a means of improving our knowledge of
the taxonomy of these mice.

     We are obliged to J. R. Alcorn and William L. Cutter for
     collecting many of the specimens used by us, to the Watkins
     Fund of the Kansas University Endowment Association and to
     the American Heart Fund for financial assistance with
     collecting the specimens, to the National Science Foundation
     for financial assistance with study of the specimens in the
     Museum, to William H. Burt of the University of Michigan,
     and to Stanley P. Young, Richard P. Manville and Viola S.
     Schantz of the Biological Surveys Collection of the United
     States Fish and Wildlife Service for lending certain
     specimens.

_Transmitted October 1, 1959._


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Transcriber's Notes:

Italicized text is shown within _underscores_.

Bold text is shown within ~tildes~.