Crotalus oreganus helleri
- Common names: Southern Pacific rattlesnake, black diamond rattlesnake, more.
is a venomous pitviper subspecies
found in South-West California
and south into Baja California
Adults are 24-55 inches (61-139 cm) in length.
The color pattern consists of a pale brown, gray-brown, or yellowish brown ground color overlaid with a series of large, dark brown dorsal blotches that may or may not have pale centers. The blotches are more diamond shaped, as opposed to those of C. o. oreganus that are more hexagonal, and are bordered by light scales. The tail rings are not clearly defined. In juveniles, the end of the tail is bright orange, but this turns to brown as the snakes mature. In adults, the base of the tail and the first segment of the rattle are brown. The postocular stripe is moderately to very clearly defined. In juveniles, this stripe is bodered above by a pale stripe, but as the snakes mature this turns to drab yellow or brown. A conspicuous pale crossbar is sometimes present across the supraoculars, after which the head is a uniform dark color. In some older snakes the head is mostly dark with almost no trace of the supraorbital crossbar, or none at all.
Southern Pacific rattlesnake, black diamond rattlesnake, black (diamond) rattler, gray diamond-back, mountain rattler, Pacific rattler, San Diegan rattler, timber rattler.
The United States in southern California
, and Mexico in northern Baja California, west of the desert. In the north from the counties of San Luis Obispo
, and south through the counties of Santa Barbara
, Los Angeles
(including Santa Catalina Island
), southwestern San Bernardino
, western Riverside
, San Diego
and extreme western Imperial
. From there its range extends south though Baja California to lat. 28° 30' North. According to Klauber (1956), the type locality
is "San Jose, Lower California" [San José, lat. 31° N, Baja California (state), Mexico].
- Ashton KG, de Queiroz A. 2001. Molecular systematics of the western rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the d-loop in phylogenetic studies of snakes. Molecular Phylogenetics and Evolution, Vol. 21, No.2, pp. 176-189. PDF at CNAH Accessed 12 December 2007.