Woodrats (Genus Neotoma) of Sinaloa, Mexico

Abstract

Sinaloa, situated on the western coast of Mexico between 22° 30' and 27° 00' north latitude and between 106° 25' and 109° 30' west longitude, is one of the few states in the ncyrthern part of that country for which a comprehensive, published survey of the native mammalian fauna is lacking. This report is one of several studies planned or in progress (see also Dunnigan, 1967) that are intended to make better known the systematics and ecology of rodents of this important transitional area between the fluctuating environment of temperate North America and the more stable environment of tropical Middle America. Hardy and McDiarmid (1969) recently studied the herptofauna of Sinaloa and summarized the physiographic, climatic, and vegetational characteristics of the state. Briefly, Sinaloa is characterized by east-west relief of about 2780 meters, from the Sierra Madre Occidental, which extends along the entire eastern edge of the state, to sea level. The northern boundary of the state transects the southern edge of the Sonoran Desert and extreme southern Sinaloa encompasses the northern extensic)n of tropical savanna. The genus Neotoma is represented in Sinaloa by four speciesa including members of three of the four currently recognized subgenera. The tnto members of the subgenus Neotomv (vlbigslv and mexisdSv) are wideranging species that occupy broad distributions in the southwestern United States and Mexico; the biological characteristics of these two species have been reported on by several authors (for example, Vorhies and Taylor, 1940; Finley, 1958; and Brown, 1969). Neotoma (Hodomys) vlleni and Neotomv (Teanopus) phenax boi are endemic to relatively restricted regions in western Mexico. Neither species has been intensively studied, although Kelson (1952) reviewed Neotomv alleni taxonomically. Specimens were aged according to criteria established by Hoffmeister and de la Torre (1960:479) for Neotoma stephensi (based on the degree of eruption and relative height of labial re-entrant angles of mdars); only animals categorized in groups 3 or 4 using iis system are regarded as adults in the accounts beyond. All measurements are expressed in millimeters; those of crania were taken by means of dial calipers and external