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Sonoran Coralsnake (Micruroides euryxanthus)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2589″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Sonoran Coralsnake, Sierra La Purica, Sonora. Photo by Jim Rorabaugh[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2590″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake, Sierra Aconchi, Sonora, MX. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2590″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake, Photo by Young Cage[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2592″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake, Photo by Young Cage[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2593″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake, Photo by Young Cage[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2594″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake, Photo by Young Cage[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2595″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Coralsnake in the web of a Black Widow, Boyce Thompson Arboretum, Pinal Co., AZ. Photo by Larry Jones. Documented in Jones et al. 2011, Herpetological Review 42(3):440-441[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

The New World Coralsnakes consist of two genera: Micrurus (79 species) and Micruroides (1 species), and as a group is distributed from the southern United States south to Argentina as well as adjacent islands.  They tend to be secretive, relatively docile, and not inclined to bite, although their venom is often of lethal toxicity.  Many are vividly banded with red, black, and yellow or white, although some species lack red bands or are mostly black.  The colorful banding pattern is warning coloration for potential predators, but can also act to conceal.  A coralsnake moving rapidly through the dappled light on a forest floor almost disappears as the banding pattern blurs and blends with its surroundings.

The sole coralsnake in our area, and the only member of the genus Micruroides, the Sonoran Coralsnake (M. euryxanthus), is unusually small (< 660 mm total length) among the coralsnakes, but exhibits the striking banding of most, with alternating black, white or yellow, and red bands that encircle the body. The white or yellow bands contact the red bands, and red bands are absent on the tail. The snout and most of the head is black, and the third band from the snout is red.  It has smooth dorsal scales in 15 rows at mid-body and the anal plate and subcaudal scales are divided.  The eye is small and the head is only slightly differentiated from the neck. A number of non-venomous snakes in our area resemble the Sonoran Coralsnake, but in many, but not all of the look-alikes, the red bands do not contact the white or yellow bands (the shovel-nosed snakes (Chionactis) are the exception), and red bands are usually present on the tail.

In the 100-Mile Circle, the Sonoran Coralsnake is widely distributed in Sonoran desertscrub, Chihuahuan desertscrub, semi-desert grassland, and the lower reaches of oak woodland at elevations of about 320-1770 m.  This is a species primarily of bajadas and rocky canyons, and is rarely found in valley bottoms.  It is active March to November, with most found during the summer monsoon season.  The Sonoran Coralsnake is primarily nocturnal or crepuscular, although it may be surface active on cool or overcast days, particularly in spring and fall.

Two to six eggs are laid in July or August, which hatch in September. Females may not produce clutches every year. This species feeds primarily on other snakes, particularly Threadsnakes (Rena), but a variety of other small snakes have been recorded in the diet. Various lizards, such as whiptails, Madrean Alligator Lizards, skinks, and night lizards may also be consumed.  Smooth-scaled reptiles are preferred.  Sonoran Coralsnakes that are captured or otherwise perceive a threat may void feces from the vent and make a popping noise by expelling air from the cloaca (cloacal popping).

The fangs are quite short (1.0 mm or less) and located in the front of the upper jaw.  The venom is neurotoxic and potent; however, the small size of this snake and its short fangs make envenomation of a human difficult. Also, they are generally not prone to bite. Nonetheless, people are sometimes bitten, causing symptoms ranging from pain and numbness to nausea, weakness, drowsiness, and muscle problems.  This species should not be handled casually.

Four Sonoran Coralsnakes may be taken each year or held in captivity with a valid Arizona hunting license. It is listed as a species of least concern on the 2013 IUCN’s Red List.

Suggested Reading:

Brennan, T.C., and A.T. Holycross. 2006. Amphibians and Reptiles in Arizona. Arizona Game and Fish Department, Phoenix, AZ.

Ernst, C.H., and E.M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Books, Washington, D.C.

Ernst, C.H., and E.M. Ernst. 2012. Venomous Reptiles of the United States, Canada, and Northern Mexico. Volumes 1 & 2. Johns Hopkins University Press, Baltimore, MD.

Goldberg, S.R. 1997. Reproduction in the western coral snake, Micruroides euryxanthus (Elapidae), from Arizona and Sonora, Mexico. Great Basin Naturalist 57:363-365.

Jones, L.L.C., A.D. King, P.A. Simpson, J. Taiz, and P. Wolterbeek. 2011. Micruroides euryxanthus (Sonoran Coralsnake). Predation. Herpetological Review 42(3):440-441.

Lowe, C.H., C.R. Schwalbe, and T.B. Johnson. 1986. The Venomous Reptiles of Arizona. Arizona Game and Fish Department, Phoenix.

Rorabaugh, J.C., and J.A. Lemos Espinal. 2016. A Field Guide to the Amphibians and Reptiles of Sonora, Mexico. ECO Herpetological Publishing and Distribution, Rodeo, NM.

Roze, J.A. 1996. Coral Snakes of the Americas: Biology, Identification, and Venoms. Krieger Publishing Co., Malabar, Florida.

Vitt, L.J., and A.C. Hulse. 1973. Observations on feeding habitats and tail display of the Sonoran Coralsnake, Micruroides euryxanthus. Herpetologica 29:302-304.

Author: Jim Rorabaugh

For additional information on this species, please see the following volume and page in the Sonoran Herpetologist: 1988-91 Collected Papers:205.

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