CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Sonoran Lyresnake - Trimorphodon lambda

Cope, 1886
Click on a picture for a larger view



Lyresnakes California Range MapRange in California: Orange

Red: California Lyresnake



observation link





Sonoran Lyresnake Sonoran Lyresnake Sonoran Lyresnake
Adult, eastern Imperial County © Keith Condon Divided anal plate of adult from eastern Imperial County © Keith Condon
 
Sonoran Lyresnakes from Outside California
Sonoran Lyresnake Sonoran Lyresnake Sonoran Lyresnake
  Adult, Santa Cruz County, Arizona  
Sonoran Lyresnake Sonoran Lyresnake Sonoran Lyresnake
Adult, Arizona, © Chris Gruenwald
  Sonoran Lyresnake  
  Adult, Santa Cruz County, Arizona  
     
Habitat
Rosy Boa Habitat Sonoran Lyresnake Habitat  
Possible habitat, eastern
Imperial County,
Possible habitat, Chemehuevi Mountains, San Bernardino County  
   
Description

Mildly Venomous - but not considered dangerous to humans.

Delivers a mild venom from rear fangs, but the venom is not considered dangerous to humans.
Handle this snake with caution, as some people have had unpleasant reactions to this snake's bite.

Size
Trimorphodon have been recorded from 18 - 47 3/4 inches in length (46 - 121 cm). Most snakes encountered are 24 - 36 inches long (61 - 91 cm).

Appearance
A slender snake with a broad head well-differentiated from the slim neck.
The pupils are vertical, like those of a cat.
The anal plate is divided.
Color and Pattern
Coloring closely matches a snake's rocky habitat, from gray to light brown.
There are usually about 28 large dorsal blotches with light edges and a pale crossbar in the center, and smaller irregular blotches on the lower sides.
A lyre-shaped marking is present on top of the head.
The underside is off-white or yellowish with dark spots.

Comparison of the Two Species of Lyresnake Found in California
Sonoran Lyresnake - Trimorphodon lambda

Has fewer body blotches than T. lyrophanes.
(Fewer than 31 primary dark body blotches - average of 24.)

Body blotches are more widely separated than those on T. lyrophanes.
(The seventh and eighth blotches are separated by an average of four scale rows.)

The anal scale is divided.



California Lyresnake - Trimorphodon lyrophanes

Has a greater number of body blotches than T. lambda.
(Fewer than 48 primary dark body blotches - (average of 34.)

Body blotches are more narrowly separated than those on T. lambda.
(The seventh and eighth blotches are separated by an average of two scale rows.)

The anal scale is divided or entire.

(From Devitt et al, 2008 * See more detailed information here.)

Life History and Behavior

Activity
Nocturnal, active in very dry conditions as well as during rains. Terrestrial, and good climbers. This snake often searches rock crevices for prey. It can be found during the day inside crevices in large rock outcrops, as well as crossing desert roads at night.
Diet and Feeding
Primarily lizards, but also known to eat small mammals, nestling birds, and snakes.
Breeding
Not well known. Lyre snakes apparently originated in the tropics, where breeding is year round, and the northern races may have retained this capability.

Habitat
Associated primarily with rocky desert locations, but found in rockless areas, also.

Geographical Range
In California, found only in the southeast along the Colorado River from the Baja California border north into San Bernardino County and the Nevada border.

Devit et al 2008 *described the entire range of Trimorphodon lambda:
"Found from southern Nevada (Nye Co.), extreme southwestern Utah (Washington Co.), south through much of Arizona except for the northeastern quarter, southwestern New Mexico (Hidalgo and Grant counties), southeastern California generally east of the Salton Trough region, south through Sonora and western Chihuahua west of the Sierra Madre Occidental, to northern Sinaloa."

In his 2006 study ** Thomas Devitt did not sample any specimens west or east of the Salton Sea in the apparent contact area, or any specimens along the Colorado River in California. He used no specimens of T. lambda from California at all, as you can see in the map detail taken from the study below. This leaves me uncertain as to exactly where the contact zone exists between T. lambda and T. lyrophanes. I have found no museum records which are identified down to subspecies that help. (Museum records still use Trimorphodon biscutatus with subspecies as I write this 2/14.) In the range maps shown in field guides from those authors who recognize the two species (or former subspecies) the area of contact is shown in more than one place; some show T. lyrophanes ranging all the way east to the Colorado River, others show its range ending somewhere northeast of the Salton Sea in Riverside County, and another shows it ranging even farther west. I have chosen to show the two species meeting west of the river in Riverside County, following Devitt's map below, however I will change this if I can obtain more accurate information. The northern range of T. lambda is also uncertain. While the maps in Devitt et al 2008 and in Devitt 2006 below show the species ranging north and west of the Colorado River into Nevada somewhere above Needles, as I have done, some maps show it ranging only as far north as the Whipple Mountains/Parker Dam area, and I can find no museum or other records of lyresnakes consistent with either interpretation, (or even any farther north than Riverside County in that area.)


From Devitt 2006 **
Full Species Range Map
Notes on Taxonomy
Devitt et al 2008 * recommended that the subspecies of Trimorphodon biscutatus - lambda, lyrophanes, and vilkinsonii, be recognized as distinct species - Trimorphodon lambda, Trimorphodon lyrophanes, and Trimorphodon vilkinsonii. They recommended that the common names be Peninsular Lyresnake for T. lyrophanesand Sonoran Lyresnake for T. lambda.

This species was formerly regarded as a subspecies of Trimorphodon biscutatus: T. b. lambda - Sonoran Lyresnake.


Alternate and Previous Names (Synonyms)

Trimorphodon lambda - Sonoran Lyre Snake (Stebbins & McGinnis 2012)
Trimorphodon biscutatus - Western Lyre Snake (Stebbins 2003)
Trimorphodon biscutatus lambda - Sonoran Lyre Snake (Stebbins 1985)
Trimorphodon lambda - Sonora Lyre Snake (Stebbins 1966)
Trimorphodon lambda - Arizona Lyre Snake (Stebbins 1954)
Trimorphodon lambda - Sonoran Lyre Snake (Cope 1886)

Conservation Issues  (Conservation Status)
None
Taxonomy
Family Colubridae Colubrids Oppel, 1811
Genus Trimorphodon Lyresnakes Cope, 1861
Species

lambda Sonoran Lyresnake Cope, 1886
Original Description
Trimorphodon lambda - Cope, 1886

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Trimorphodon - Greek - tri - three, and morph - shape, and odon- teeth - refers to the 3 tooth shapes in the upper jaw,                            recurved anterior teeth;  the shorter middle teeth, and elongate grooved fangs at the rear.
lambda - Greek - letter of Greek alphabet - refers to the chevron-shaped mark on head

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Related or Similar California Snakes
T. lyrophanes - Baja California Lyresnake
Sonoran Gopher Snake
Desert Glossy Snake

More Information and References
California Department of Fish and Wildlife

Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Snakes of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Bartlett, R. D. & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000.

Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997.

Ernst, Carl H., Evelyn M. Ernst, & Robert M. Corker. Snakes of the United States and Canada. Smithsonian Institution Press, 2003.

Wright, Albert Hazen & Anna Allen Wright. Handbook of Snakes of the United States and Canada. Cornell University Press, 1957.

* Devitt, Thomas J., Travis J. LaDuc, and Jimmy A. McGuire. The Trimorphodon biscutatus (Squamata: Colubridae) Species Complex Revisited: A Multivariate Statistical Analysis of Geographic Variation. Copeia. 2008 (2): 370-387.

** Devitt, T. J. Phylogeography of the Western Lyresnake (Trimorphodon biscutatus): testing aridland biogeographi- cal hypotheses across the Nearctic–Neotropical transition. Molecular Ecology 2006 15:4387–4407.

Conservation Status

The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.


This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Organization
Status Listing
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None
IUCN

 

Home Site Map About Us Identification Lists Maps Photos More Lists CA Snakes CA Lizards CA Turtles CA Salamanders CA Frogs
Contact Us Usage Resources Rattlesnakes Sounds Videos FieldHerping Yard Herps Behavior Herp Fun CA Regulations
Beyond CA All Herps


Return to the Top

 © 2000 -