The Baja California rat snake (Bogertophis rosaliae) is a species of nonvenomous snake in the family Colubridae. The species is native to Baja California, Mexico; extreme southern California; and some islands in the Sea of Cortés. Description The Baja California rat snake is a large, slender colubrid snake with a long head, large eyes, and smooth dorsal scales. Adults have a total length (including tail) of . Each dorsal scale contains two apical pits (Price 1990a, 1990b). The dorsum is uniform olive or reddish brown without dark markings on a cream-colored background (Ottley and Jacobsen 1983). Yellowish or greenish coloration extends from the lower sides of the body to the venter (Price 1990b). The iris is yellow-green (Ottley and Jacobsen 1983). Taxonomic remarks Dowling and Price (1988) placed this snake in its own genus, Bogertophis, based on immunological data, but complications with the data set and the mode of analysis indicated that it was best to regard this species as a member of the rat snake genus, Elaphe, until further data became available (L. Grismer and John Wright, pers. comm.). No attempts have been made to characterize genetic variation across the geographic range of B. rosaliae. An understanding of that variation is needed to determine whether genetically differentiated populations exist within B. rosaliae. The difficulty in obtaining the requisite material for such a study makes it likely that novel techniques, such as extracting DNA from preserved specimens, will be needed to address this problem. Geographic range The Baja California rat snake ranges from extreme southern Imperial County, California, southward into Baja California to Cabo San Lucas (Price 1990a). Over at least the northern half of its range, it is known from widely disjunctive locations (Ottley and Jacobsen 1983, Price 1990b). Its known elevations range from near sea level to ca. . In the United States, B. rosaliae is known from only one road-killed specimen, CSDSNH 644161 taken 26 May 1984 on Interstate Highway 8, east of Mountain Spring (Imperial County), California. Although Stebbins (1985) and others believe this locality to be genuine (L. Grismer and G. Pregill, pers. comm.), some have questioned the validity of this record (S. Barry, J. Copp, and C. Fagan, pers. comm.). Life history The life history of B. rosaliae is virtually unknown (Price 1990b). The species seems to be nocturnal or crepuscular and may be surface active during daylight hours under suitable conditions (Ottley and