Webb’s Mountain Kingsnake — Lampropeltis webbi Bryson, Dixon & Lazcano 2005 

Other Common Names: Sinaloan Mountain Kingsnake, Webb’s Kingsnake

Spanish Name: None

Original Description: Bryson, R. W., Jr., J. R. Dixon, and D. Lazcano. 2005. New species of Lampropeltis (Serpentes: Colubridae) from the Sierra Madre Occidental, México. Journal of Herpetology 39(2):207–214. 

Holotype & Type Locality: UANL 5684, collected by Robert Bryson, Deron Hartman, and Javier Banda on 30 June 2000, from 4.0 km west of El Palmito on Hwy. 40, Municipio Concordia, Sinaloa, México (23° 33’ 14.2” N, 105° 50’ 47.2” W), 2000 m elevation.

Etymology: The species name is a patronym honoring University of Texas at El Paso herpetologist Robert G. Webb, foremost student of the herpetofauna of the Sierra Madre Occidental, and scientific describer of L. greeri

Scientific Describers: Robert W. Bryson, Jr. (1976–) was a graduate student at Sul Ross State University (Alpine, Texas) during this period of field work in Mexico. Subsequently, Bryson earned his Ph.D. at University of Nevada at Las Vegas, focusing on evolutionary patterns in Mexican herpetofauna. James Ray Dixon (1928–2015) was a long-time faculty member at Texas A&M University, and was one of the most productive herpetological systematists working in the New World, having described many new species of amphibians and reptiles. Several species or subspecies are named in his honor, including Lampropeltis triangulum dixoni (Dixon’s Milksnake), the Southeast Asian gecko genus DixoniusAspidoscelis dixoni (Gray Checkered Whiptail), Phyllodactylus dixoni (Dixon’s Leaf-toed Gecko), and a South American frog (Eleutherodactylus dixoni). David Lazcano Villareal is Professor and Curator of the herpetology collection at the Universidad Autónoma de Nuevo León, in Monterrey, México.  He has been very active in conducting systematic field surveys of the herpetofauna, focusing mainly on the states of Nuevo León and Tamaulipas. He and Bryson are frequent collaborators and have co-authored numerous publications. 

Distribution: This is a recently described species of Lampropeltis, known from only a few specimens, all taken from along the Highway 40 corridor on both sides of the Sinaloa-Durango border in the Sierra Madre Occidental. There are just two specimens in museum collections, both obtained as roadkills about 10 km apart on Highway 40. Several additional snakes have been found in the last few years, but there are no living examples outside of Mexico.

    Webb’s Mountain Kingsnake occupies the extremely rugged, heavily vegetated barranca region straddling the Sinaloa-Durango border. Not only is field hunting impractical because of the difficult terrain, but the region is one of Mexico’s most dangerous, given the high levels of narcotraficante activity. Thus, it is not surprising that this species would remain hidden from scientific discovery until the 21st century. Interestingly, a single DOR specimen, obtained in 1968, sat in a jar of alcohol in the Fort Worth Museum of Science and History in Texas. Not considered much of a repository for scientific specimens, this Fort Worth specimen went unnoticed by herpetologists for many years. Examination revealed it to be the same species as the DOR collected by Bryson and crew in the summer of 2000.  

Habitat: The Mixed Boreal-Tropical Forest community extends north and south of the Highway 40 corridor, and presumably L. webbi will eventually be discovered elsewhere. However, as presently understood, the range of webbi lies outside the known ranges of nearby species of LampropeltisL. pyromelana knoblochi, L. greeri, and L. ruthveni, although L. greeri occurs on the cooler, drier eastern slopes of the Sierra Madre along Hwy 40.Additionally, Lampropeltis polyzona (Tropical Milksnake) occurs to the west of L. webbi in the coastal plain and foothills of Sinaloa, but it seems unlikely that this species and L. webbi come in contact along the rugged Highway 40 corridor.

    For interested readers, there is an excellent paper by Robert Webb—“Herpetogeography in the Mazatlán-Durango region of the Sierra Madre Occidental, Mexico” (published in 1984 in a volume called “Vertebrate Ecology and Systematics: A Tribute to Henry S. Fitch” [edited by R. A. Seigel et al.], published by the University of Kansas Museum of Natural History). Webb provides a nice description of the region’s topography and vegetation, and includes b/w photos of “Mixed Boreal-Tropical” forest. Here is a brief excerpt of Webb’s description of this area: “The Mixed Boreal-Tropical covers rugged, mountainous terrain at the highest elevations in large barrancas and canyons, and is best developed on south-facing slopes. Steep, boulder-strewn hillsides with rock outcrops, interrupted by small, relatively level areas, are covered in most places with a tall pine-oak woodland and often a dense understory of herbs, shrubs, and thick tangles of vines…. This region occurs for approximately 51 km (32 mi) along Highway 40 between elevations of …7900 and 5900 ft….”

    Clearly, the range of L. webbi is much larger than present records suggest, although lack of roads, rugged terrain, and criminal activity will make expanding our field knowledge of this species a great challenge! 

Growth and Size: There are too few specimens available to permit any meaningful summary of adult size, but the handful of DOR and living specimens have been < 70 cm TL. 

Pattern Variation: The few available specimens were taken within a relatively small area and were similar to one another in overall pattern and coloration. Features these specimens have in common are: grayish-white body rings joined laterally beneath the red-orange body blotches, forming a chain-like pattern. The red-orange blotches are edged in black, and do not reach the ventral surface, instead tapering laterally. The ventral surface is mottled/checkered with black, light gray, and light red-orange. The head pattern is different in each of five specimens; in general, the head pattern can be characterized as off-white to gray with variable amounts of black pigment dorsally, and with or without red-orange markings on the top of the head. 

Relationships: Based on mtDNA data, L. webbi is allied with L. pyromelana and L. mexicana, but clearly distinct from both species More recently, DNA sequences from nuclear genes suggest a sister relationship with L. ruthveni + L. mexicana.  In general, color and pattern do not appear to be particularly reliable indicators of phylogeny in Mexicana kings. In the case of webbi, there are pattern elements that resemble those observed in ruthveni, mexicana, and greeri, but taken together are unique. 

Conservation Status: As presently understood, this species has the smallest range of any Mexican Lampropeltis other than the island endemic L. herrerae (Todos Santos Kingsnake), although we expect that with additional field work, the known range of webbi will be expanded. The rugged terrain in which this species occurs probably ensures that it will be only modestly affected by human alterations to the habitat. 

Captive Stock: None known to be in captivity.