Micruroides euryxanthus, commonly known as the Sonoran coral snake or the Arizona coral snake, is a species of venomous elapid, which is endemic to northwestern Mexico and the Southwestern United States.
Adults are 11–24 inches (280–610 mm) in total length (including tail).
The color pattern consists of broad, alternating rings of red and black, separated by narrower rings of white or yellow. Markings become paler as they reach the belly. The head is black, the black extending to the posterior border of the parietals.
The smooth dorsal scales are arranged in 15 rows at midbody. Ventrals 214-241; anal plate divided; subcaudals 21-34, also divided (paired).
Micruroides euryxanthus resembles Micrurus fulvius. However, the white or yellow rings are broader than in Micrurus fulvius, and there are fewer black rings on the tail, usually only 2. Also, the first ring on the body (the first ring behind the white or yellow ring on the back of the head) is red, whereas in Micrurus fulvius it is black.
The venom is neurotoxic and extremely potent, but no fatalities have been reported.
M. euryxanthus is found in arid/semiarid regions in numerous habitats, both on plains and on lower mountain slopes, from sea level to 5,800 ft (1,800 m). In Arizona it is abundant in rocky upland desert.
The Sonoran coral snake usually stays underground and comes out at night, but can also appear during and after rains.
When startled or threatened, M. euryxanthus will hide its head under its body and raise and tightly curl its tail. While in this posture, it will sometimes forcibly and noisily emit gas from its cloaca, a behavior known as “cloacal popping”.
The Arizona coral snake preys upon small snakes, predominantly Leptotyphlops, but also Chionactis, Hypsiglena, Sonora, and Tantilla. It will also eat small lizards such as skinks.
Like all other species of New World coral snakes (genera Leptomicrurus and Micrurus), Micruroides euryxanthus is oviparous. Adult females may lay up to 3 eggs, and the hatchlings are 18–20 cm (7-8 inches) in total length.
Micruroides euryxanthus is found from central Arizona and southwestern New Mexico to Mazatlán in southern Sinaloa. Isolated populations are also found in the Chocolate Mountains, La Paz County, western Arizona and on Tiburón Island in the Gulf of California.