ROBERT L. PACKARD
UNIVERSITY OF KANSAS
LAWRENCE
1958
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,Robert W. Wilson
Volume 9, No. 15, pp. 397-404Published December 19, 1958
UNIVERSITY OF KANSASLawrence, Kansas
PRINTED INTHE STATE PRINTING PLANTTOPEKA, KANSAS1958
27-5660
BY
ROBERT L. PACKARD
The southern pygmy mouse, Baiomys musculus, is known as far north asthe Mexican states of Jalisco, Michoacán, south of the Mesa Central,east to central Veracruz (see Hooper, 1952a:90), and south to westernNicaragua (see Goodwin, 1942:161). Previously, two subspecies have beenrecognized from the southern part of the known range of this species:B. m. nigrescens, blackish mice from Chiapas, México, and Guatemala,and B. m. grisescens, grayish-brown mice from Honduras and westernNicaragua. Study of recently acquired specimens from Guatemala, ElSalvador, and Nicaragua reveals two additional subspecies.
For the loan of comparative material, I am grateful to the United StatesNational Museum (USNM) and the American Museum of Natural History(AMNH). Unless otherwise indicated, specimens are in the University ofKansas Museum of Natural History. Measurements are as taken by Hooper(1952b:10). Postpalatal length is the distance from the posterior marginof the hard palate to the anterior margin of the foramen magnum. Unlessotherwise noted, statistical significance as used in this paper is atthe 95 per cent confidence limit or higher.
The two heretofore undescribed subspecies are characterized below andmay be known as:
Baiomys musculus handleyi, new subspecies
Type.—Adult female, USNM No. 275604 (Biological SurveysCollection), skin and skull; from Sacapulas, El Quiché, Guatemala;obtained on April 24, 1947, by Charles O. Handley, Jr., originalnumber 991.
Distribution.—Known only from the type locality; probablyinhabits parts of the east-west drainage of the Río Negro.
Diagnosis.—General ground color of upper parts between WoodBrown and Buffy Brown (all capitalized color terms are those ofRidgway, Color Standards and Color Nomenclature, Washington, D. C.,1912), dorsal parts of fore- and hind-feet, and ankles white; inregion of median venter, throat, and chin, hairs white to base; inlateral regions hairs Neutral Gray at base; dorsal hairs below tipsAvellaneous, Neutral Gray at base; guard hairs black-tipped; tailwhite below, brownish above; nasals truncate anteriorly;frontalparietal suture forming an obtuse angle with median-parietal[Pg 400] suture; alveolar-length of upper molar tooth-row and tail long.
Comparisons.—From Baiomys musculus nigrescens (paratypes, fromthe Valley of Comitán, Chiapas, México), found to the north, B. m.handleyi differs in: color paler dorsally and ventrally; fore- andhind-feet whitish instead of dusky to sooty; hairs in region offacial vibrissae white instead of brown; tail bicolored instead ofunicolored; anterior tips of nasals square, not rounded;frontoparietal suture forming obtuse angle with median parietalsuture instead of a right angle; tail and a