THE CENTER FOR NORTH AMERICAN HERPETOLOGY

Reptilia    Squamata (part-snakes)    Crotalidae  

Ridge-nosed Rattlesnake
Crotalus willardi Meek, 1906
KROH-tah-lus — WIL-lard-eye

SSAR 9th Edition Comments:
 There are no current SSAR comments for this taxon.

Range maps are based on curated specimens and provided gratis by CNAH.
(Created by Travis W. Taggart; Version: 2023.04.08.12.46.05)
Download GeoJSON polygon range file: - 0.45 MB

Province/State Distribution:
United States: Arizona New Mexico

Taxonomic Etymology:
A small montane species from the southwestern U.S. named for its discoverer.
Crotalus — From the Greek word κρόταλον (krótalon); meaning: “Rattle, castanet, or clapper”. In ancient Greek, krotalon referred to a percussive musical instrument used in dances or rituals — similar to modern castanets.
willardi — Patronym honoring Frank C. Willard (1885?-1936?), a businessman and amateur naturalist from Tombstone, Arizona. He collected the type specimen of the snake in Ramsey Canyon, near the town of Hamburg.

First instance(s) of published English names:
Willard's Rattlesnake (Crotalus willardi: Van Denburgh, John. 1922. The Reptiles of Western North America: An Account of the Species Known to Inhabit California and Oregon, Washinton, Idaho, Utah, Nevada, Arizona, British Columbia, Sonora, and Lower California. Volume I. Lizards. California Academy of Sciences, San Francisco. 556pp.); Willard's Rattlesnake (Crotalus willardi: Schmidt, Karl Peterson and D. D. Davis. 1941. Field Book of Snakes of the United States and Canada. C.P. Putnam and Sons, New York. 365pp.); Ridge-nosed Rattlesnake (Crotalus willardi: Schmidt, Karl P. 1953. A Check List of North American Amphibians and Reptiles. 6th Edition. University of Chicago Press, Chicago, Illinois. 280pp.); Arizona Ridge-nosed Rattlesnake (Crotalus willardi willardi: Schmidt, Karl P. 1953. A Check List of North American Amphibians and Reptiles. 6th Edition. University of Chicago Press, Chicago, Illinois. 280pp.); New Mexican Ridge-nosed Rattlesnake (Crotalus willardi obscurus: Harris, Herbert, Jr., and R. S. Simmons. 1976. The paleogeography and evolution of Crotalus willardi, with a formal description of a new subspecies from New Mexico, United States. Bulletin of the Maryland Herpetological Society 12(1):1-22); West Chihuahua Ridge-nosed Rattlesnake (Crotalus willardi silus: Harris, Herbert, Jr., and R. S. Simmons. 1976. The paleogeography and evolution of Crotalus willardi, with a formal description of a new subspecies from New Mexico, United States. Bulletin of the Maryland Herpetological Society 12(1):1-22);

Taxon Links:

  
Catalog of American Amphibians and Reptiles
  
The Reptile Database
  
NatureServe
  
iNaturalist
  
GenBank
  
USGS - Nonindigenous Aquatic Species Database

Selected References:
1906 "1905" Meek, Seth Eugene. An annotated list of a collection of reptiles from southern California and northern lower California. Field Columbian Museum Publication 104 8(1):3-19
1940 Gloyd, Howard K. The rattlesnakes, genera Sistrurus and Crotalus. Chicago Academy of Sciences Special Publication 4(1):1-266
1949 Klauber, Laurence M. The subspecies of the Ridge-nosed Rattlesnake, Crotalus willardi. Transactions of the San Diego Society of Natural History 11(8):121-140
1956 Klauber, Laurence M. Rattlesnakes. Their habits, life histories, and influence on mankind. 2 Volumes. University of California Press, Berkeley, California. pp.
1961 Bogert, Charles M. and William G. Degenhardt. An addition to the fauna of the United States, the Chihuahua Ridge-nosed Rattlesnake in New Mexico. American Museum Novitates (2064):1-15
1962 Anderson, James D. A new subspecies of the Ridge-nosed Rattlesnake, Crotalus willardi, from Chihuahua, Mexico. Copeia 1962(1):160-163
1972 Klauber, Laurence M. Rattlesnakes. Their Habits, Life Histories, and Influence on Mankind. 2 Vols. 2nd ed. University of California Press, Berkeley and Los Angeles. pp.
2002 Holycross, Andrew T., Michael E. Douglas, J. R. Higbee, and R. H. Brogden. Isolation and characterization of microsatellite loci from a threatened rattlesnake (New Mexico Ridge-nosed Rattlesnake, Crotalus willardi obscurus). Molecular Ecology Notes 2:537–539
2007 Holycross, Andrew T. and Michael E. Douglas. Geographic isolation, genetic divergence, and ecological non-exchangeability define ESUs in a threatened sky-island rattlesnake. Biological Conservation 134(2007):142-154
2024 Pillod, David S., Michelle I. Jeffries, Robert S. Arkle, and Deanna H. Olson. Climate futures for lizards and snakes in western North America may result in new species management issues Ecology and Evolution 14(10):1-23
2024 Myers, Edward A., Rhett M. Rautsaw, Miguel Borja, Jason Jones, Christoph I. Grünwald, Matthew L. Holding, Felipe Grazziotin, and Christopher L. Parkinson. Phylogenomic discordance is driven by wide-spread introgression and incomplete lineage sorting during rapid species diversification within rattlesnakes (Viperidae: Crotalus and Sistrurus) Systematic Biology syae018:

THE CENTER FOR NORTH AMERICAN HERPETOLOGY — Accessed: Friday 05 December 2025 15:58 CT