The pigmy woodrat, Neotoma goldmani Merriam, the smallestknown member of the genus, inhabits rocky areas in the elevateddesert regions of the northern part of the Mexican Plateau (Mesadel Norte). Goldman (N. Amer. Fauna, 31:82, October 10, 1910)had for study ten specimens from two localities in Coahuila. Sincehis report, Dalquest (Louisiana State Univ. Studies, Biol. Sci. Ser.No. 1:162, December 28, 1953) extended the known distributionof this species approximately 225 miles southward into San LuisPotosí, where he reported animals from five localities. Fieldworkers from the Museum of Natural History at the University ofKansas recently have taken goldmani in the Mexican states ofChihuahua, Coahuila, Durango, Zacatecas and San Luis Potosí, andnow we can define, with greater accuracy, the geographic rangeof this species (see fig. 1 and list of specimens examined).
Goldman (loc. cit.), relying chiefly on external appearance,placed goldmani in the desertorum group, now known as thelepida group (Goldman, Jour. Mamm., 13:67, February 9, 1932).Blossom (Occ. Papers Mus. Zool., Univ. Michigan, 315:3, May 29,1935) thought that goldmani might be a subspecies of lepida butthat intergradation between the two had not been demonstrated.Our newly acquired material, instead of confirming the opinions ofGoldman and Blossom, shows that goldmani is more closely relatedto Neotoma albigula.
Externally goldmani resembles Neotoma lepida (examples fromCalifornia, Utah, and Colorado) in having long, silky pelage;ochraceous buffy coloring, especially along sides; and underpartsbasally plumbeous except for a small throat patch where the hairsare entirely white in some individuals. In albigula this patch ofwhite hairs usually is much larger and more conspicuous. Cranially,instead of resembling the lepida group (including Neotomastephensi), goldmani looks more nearly like a miniature albigula(specimens of albigula from Coahuila). The auditory bullae, inrelation to the length of the skull, are of comparable size in goldmani[Pg 622]and albigula whereas those of the lepida group are proportionatelymuch larger. Moreover, the posterior margin of the palatalbridge is concave in goldmani and albigula instead of truncateas in the lepida group. Neotoma goldmani differs from both albigulaand lepida in: ascending branches of premaxillaries broaderposteriorly; supraorbital ridges less pronounced; rostrum less massive;interp