Chapter I

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 Rio 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 Rio 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.

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 Rio 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 Culiacan, 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, Rio 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 Culiacan 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, Rio
Mayo, 10 U. Mich.; 1-1/2 mi. SW Tocuina [Tocuina is a
construction camp, in 1959, on NW bank of the Rio
Septentrion, 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
Culiacan, 29 K. U.; 32 mi. SSE Culiacan, 20 K. U.; 6 mi. N,
1/2 mi. E El Dorado, 41 K. U.; El Dorado, 2 K. U. Sonora:
Rio "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~.