THE TAXONOMIC STATUS OF THE WYOMING TOAD, BUFO BAXTERI PORTER

Abstract

Although discovered by George Baxter in 1946 (Baxter and Meyer, 1982), existence of the Wyoming Toad was apparently fi rst recorded by Stebbins (1954: 143, map p. 145), who learned about it from Baxter (Stebbins, personal communication) and listed it from Albany Co., southeastern Wyoming, under the name of Bufo hemiophrys Cope. The range of that species is otherwise limited to central western Canada and northern parts of the adjacent United States (Montana, North Dakota, Minnesota), southward in the Red River drainage to northeastern South Dakota. Thus a minimum of about 800 airline km separates the range of the Wyoming toad from that of its more northern closest relative (Figure 1). The Wyoming population, abundant within 30 miles (48.3 km) of Laramie in the 1950’s (Baxter and Meyer, 1982), is now thought to be extinct in nature (Baxter and Stone, 1985; Baxter, personal communication), none having been seen in the wild for some ten years, except for captive-bred releases. The species is federally classifi ed as endangered and requires both federal and state permits for any activity involving it (Levell, 1997). However, specimens have been bred very successfully in several zoos and facilities of the Wyoming Game and Fish Department, with hopes of reestablishing the population in sanctuaries within the limits of its historical range. Following his original report, Stebbins continued (1966) to refer the Wyoming population to Bufo hemiophrys, but added a more specifi c range: “along the Big and Little Laramie Rivers to about 15 miles north and 15 miles west of Laramie.” Conant (1958, 1975) and Conant and Collins (1991) mapped, but did not name or discuss in detail this population in their guides to the eastern and central herpetofauna of North America, because this population fell outside the geographic range covered by them. It remained for Porter (1968) to regard the Wyoming population as taxonomically distinct, naming it Bufo hemiophrys baxteri (holotype formerly KRP 5-164, now USNM 166434). That subspecies has been generally accepted since then (e.g., Baxter and Stone, 1980, 1985; Stebbins, 1985; Collins et al., 1978, 1982; Sanders, 1987; ABSTRACT: The population of toads in southeastern Wyoming named Bufo hemiophrys baxteri by Porter in 1968 is presumed to be extinct in nature, except perhaps for released, captive-bred specimens. It is suffi ciently distinct in several respects, and suffi ciently isolated geographically from its nearest relative, B. h. hemiophrys, that it should be regarded as a distinct species, forming a superspecies group with B. hemiophrys.