In this section we provide a chronology of taxonomic changes and phylogenetic arrangements concerning snakes of the Lampropeltis mexicana complex: alterna, greeri, leonis, mexicana, ruthveni, and webbi. The fact that such a summary is necessary is testament to the historical difficulty in arriving at a satisfactory, robust taxonomy for this group. This is, in part, a combination of the challenges in acquiring needed specimens (hard-to-find snakes in hard-to-get-to places in a country that has not always welcomed non-Mexican scientists), and a group of snakes that apparently has experienced a rapid, recent radiation. There is a murkiness concerning species boundaries (how many species are represented?) and inter-species relationships. Indeed, it remains to be seen just which forms belong in a “mexicana group” or even if such a grouping reflects evolutionary history. However, in a recent paper, Hansen & Salmon (2017) summarized the history of scientific research involving these snakes, presented updated and detailed range maps, offered taxonomic recommendations, and discussed conservation status. If you want the most up-to-date treatment of this group, check out that paper first.
What follows is a chronological list, with annotations, of relevant published works. As new material comes to light, this section will be updated. For additional references, or for links to downloadable files, please check the Bibliography page.
1884 — Garman, S. The reptiles and batrachians of North America, Part I, Ophidia. Memoirs of the Museum of Comparative Zoology, Harvard 8(3):xxxi–185. Original description of L. mexicana, based on two females collected near Cd. San Luis Potosí (SLP).
1893 — Günther, A. C. Biologia Centrali-Americana: Reptilia and Batrachia. 1885–1902: xx + 326 pp. Original description of Lampropeltis leonis, based on a specimen from Nuevo Leon. The presumed type specimen is illustrated by a line drawing, and clearly represents the leonis-phase morph of “thayeri.” If one is to recognize the snake occurring in Nuevo Leon-Tamaulipas-Coahuila as distinct from L. m. mexicana, the correct name is L. m. leonis (or L. leonis).
1897 — Dugès, A. Description d’un Ophidien nouveau du Mexique (Oreophis boulengeri, g. et. sp. nn.). Proceedings of the Zoological Society of London 1897:284–285. Dugès erected a new genus and species for a specimen collected from the Sierra de Santa Rosa, Guanajuato. This was later placed in the synonymy of L. mexicana by Dunn (1922).
1902 — Brown, A. E.A new species of Ophibolus from western Texas. Proceedings of the Academy of Natural Sciences of Philadelphia 53:612–613, pl. 34. Original description of Lampropeltis alterna (as Ophibolus alternus) from the Davis Mountains of west Texas.
1920 — Blanchard, F. N. Three new snakes of the genus Lampropeltis. Occasional Papers of the Museum of Zoology, University of Michigan (81):1–10, 1 plate. Original description of Lampropetis ruthveni, based on a specimen from Patzcuaro, Michoacan.
1922 — Dunn, E. R. Note on Lampropeltis mexicana (Garman). Proceedings of the Biological Society of Washington 35:226. Dunn places Oreophis boulengeri Duges (1897), based on a specimen from Guanajuato, in the synonymy of L. mexicana.
1924 — Loveridge, A. A new snake of the genus Lampropeltis. Occasional Papers of the Boston Society of Natural History 5:137–139. Original description of L. thayeri, based on a specimen collected at Miquihuana, Tamaulipas. Loveridge clearly distinguishes this taxon from L. mexicana. He also reports on four recently-collected specimens of L. mexicana from near Alvarez, San Luis Potosí, which he erroneously (and inexplicably) refers to L. leonis.
1942 — Smith, H. M. Remarks on the Mexican kingsnakes of the triangulum group. Proceedings of the Rochester Academy of Sciences 8:197–207. Smith includes two figures—dorsal and ventral views—of the type specimen of Oreophis boulengeri Dugès (= L. mexicana); these are the same figures as printed in Smith and Necker 1943. Smith examined the series of 12 known specimens of L. mexicana from San Luis Potosí, comparing these to the single Dugès specimen from Guanajuato, finding general pattern similarities. He suggests that hemipenial characters place L. mexicana within the triangulum group. Smith elaborates on the specimen of L. alterna he obtained from just west of Saltillo, Coahuila (see Smith 1941 for details), and on the basis of hemipenial morphology and color pattern, acknowledges the relationship with L. mexicana, and further suggests that L. leonis (at this time known from but a single specimen) belongs with these two in a “mexicana subgroup.” Meanwhile, L. ruthveni and thayeri are placed in a “pyromelana subgroup” with knoblochi (then considered a full species), pyromelana, and zonata.
1944 — Smith, H. M. Snakes of the Hoogstraal Expeditions to northern Mexico. Zool. Ser. Field Mus. Nat. Hist. 29(8):135–152. An early attempt to make sense of the phylogeny of the mexicana group of snakes. Reports the collection of 3 specimens of L. leonis (leonis morphs), under the name L. thayeri, from near Galeana, which until this time was represented only by the type specimen. Examination of this new material caused Smith to modify composition of his “mexicana subgroup” to include thayeri, leonis, alterna, and mexicana.
1950 — Flury, A. A new king snake from Trans-Pecos Texas. Copeia 1950(3):215–217. Original description of Lampropeltis blairi, based on a single specimen from Terrell County, Texas. Later, Tanzer (1970) would demonstrate that blairi and alterna patterns could emerge from a single clutch, and blairi was reduced to a junior synonym of alterna (the older of the two names).
1961 — Webb, R. G.A new kingsnake from Mexico, with remarks on the Mexicana Group of the genus Lampropeltis. Copeia 1961(3):326–333. Original description of L. greeri from the Sierra Madre Occidental southwest of Ciudad Durango. Webb placed greeri with other species of the mexicana group based on color pattern elements. He also provides a B/W figure of the holotype of thayeri.
1962 — Gehlbach, F. R., and J. K. Baker. Kingsnakes allied with Lampropeltis mexicana: taxonomy and natural history. Copeia 1962(2):291–300. An early attempt to make sense of the phylogeny of this complex. L. alterna, L. blairi, L. greeri, L. mexicana, and L. thayeri are regarded as conspecific (under the oldest available name, L. mexicana, with five subspecies). They propose that this “mexicana complex” is distinct relative to L. doliata (= triangulum), L. pyromelana, and L. zonata. The type (and only known) specimen of L. leonis is briefly discussed, and this is regarded as a species distinct from L. mexicana. List of museum material available at the time.
1965 — Gehlbach, F. R., and C. J. McCoy, Jr. Additional observations on variation and distribution of the gray-banded kingsnake, Lampropeltis mexicana (Garman). Herpetologica 21(1):35–38. Report on L. alterna from Coahuila. Refer a specimen from 42 mi S Cd Durango (UCM 21061) to mexicana x alterna, and regard the type specimen of L. greeri as a mexicana x alterna intergrade. They thus place greeri in the synonomy of L. m. mexicana.
1967 — Gehlbach, F. R. Lampropeltis mexicana. Catalogue of American Amphibians and Reptiles 55:1–2. Review of the taxonomy, distribution, and relevant literature of L. mexicana. At this time, L. mexicana included the subspecies alterna, blairi, mexicana, and thayeri. This was published just prior to Tanzer’s discovery that alterna and blairi phenotypes could be produced in a single clutch.
1970 — Tanzer, E. C. Polymorphism in the mexicana complex of kingsnakes, with notes on their natural history. Herpetologica 26(4):419–428. [Tanzer followed Gehlbach’s construction of L. mexicana as a broadly defined taxon, inclusive of alterna, mexicana (+greeri), and thayeri. Importantly, Tanzer demonstrated that L. mexicana alterna and L. mexicana blairi were pattern morphs of the same species, and that the name alterna had priority (thus reducing the name blairi to a junior synonym of L. mexicana alterna). He also reported on the first specimen of alterna from Durango, suggesting that pattern element similarities between this specimen and the single known example of L. leonis “suggests that leonis might be part of the mexicana complex.” Tanzer’s discovery of extensive pattern variation across Texas populations of alterna led him to speculate about the potential for such phenomena elsewhere in the range of L. mexicana, and that L. thayeri might be a blairi phase of alterna. Although this suggestion might seem farfetched to modern students of the group, Tanzer and his contemporaries were severely hampered by the scarcity of specimens available for study. Interestingly, given what we now know of pattern diversity in L. leonis, his comment about the potential for polymorphism in other mexicana seems wonderfully insightful.
1973 — Blaney, R. M. Lampropeltis Fitzinger. Catalogue of American Amphibians and Reptiles (150):1–2. Offers support for Tanzer’s (1970) assessment that Lampropeltis leonis (Günther) is a synonym of L. mexicana.
1978 — Williams, K. L. Systematics and Natural History of the American Milk Snake, Lampropeltis triangulum. Milwaukee Public Museum, Publications in Biology and Geology, Number 2. 258 pp. In this published version of Williams’ Ph.D. dissertation, he relegates L. ruthveni to the synonymy of L. triangulum arcifera. Clearly, he was hampered by the paucity of preserved material from Jalisco, Michoacan, and Querétaro, and by the fact that Blanchard’s type specimen of ruthveni was represented only by a skin. Additionally, Williams seems to have been influenced by H. M. Smith’s 1942 resurrection of L. t. arcifera, to which Smith assigned various specimens from the full west-to-east extent of the Mexican Plateau; some of these have subsequently been assigned to other taxa (e.g., L. t. dixoni for TCWC 29504, from near Jalpan, Queretaro) and others no doubt pertain to L. ruthveni. An accurate assessment of “arcifera” has long been elusive, given the vagueness of the type locality (“Mexique”), as the works of Smith and Williams illustrate. Williams provides line drawings that depict head and midbody patterns of the holotype of ruthveni.
1982 — Garstka, W. R. Systematics of the Mexicana species group of the colubrid genus Lampropeltis, with an hypothesis [of] mimicry. Breviora (466):1–35. Garstka reduces thayeri to the synonomy of L. mexicana, regards L. alterna and L. mexicana as distinct species, and, importantly, resurrects L. ruthveni from the synonomy of L. triangulum arcifera (where it was buried by Williams, 1978) and includes it as a member of this species group.
1998 — Hilken, G., and R. Schlepper. Der Lampropeltis mexicana-Komplex (Serpentes, Colubridae): naturgeschichte und terrarienhaltung. Salamandra 34(2):97–124. Without presenting any new data, authors regard this complex as comprised of L. mexicana (with 3 subspecies: mexicana, greeri, thayeri), L. ruthveni, and L. alterna (with blairi and alterna as separate subspecies—clearly in conflict with available evidence).
2000 — Crother, B. I. (ed). Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. 5th edition. SSAR Herpetological Circular No. 29. 82 pp. Curiously, the authors followed Hilken & Schlepper (1998) and chose to recognize two subspecies of L. alterna, despite the fact that those authors presented no evidence in support of formal recognition of variation within L. alterna.
2002 — Bryson, R. W., Jr. Phylogenetic relationships of the Lampropeltis mexicana complex (Serpentes: Colubridae) as inferred from mitochondrial DNA sequences. Master’s thesis, Sul Ross State University, Alpine, Texas. 53 pp. Bryson offers several phylogenetic scenarios for L. alterna, mexicana, ruthveni, triangulum, and the undescribed (at that time) webbi, based on mtDNA sequence data. A favored tree is discussed in a biogeographic context.
2005 — Bryson, R. W., Jr., J. R. Dixon, and D. Lazcano. New species of Lampropeltis (Serpentes: Colubridae) from the Sierra Madre Occidental, México. Journal of Herpetology 39(2):207–214. Original description of Lampropeltis webbi from the Pacific versant of the Sierra Madre Occidental near the Sinaloa//Durango border region. MtDNA sequences and morphological characters are used to distinguish this form from putative nearest relatives L. pyromelana and L. mexicana.
2007 — Bryson, R. W., Jr., J. Pastorini, F. T. Burbrink, and M. R. J. Forstner.A phylogeny of the Lampropeltis mexicana complex (Serpentes: Colubridae) based on mitochondrial DNA sequences suggests evidence for species-level polyphyly within Lampropeltis. Molecular Phylogenetics and Evolution 43:674-684. Although the authors do not offer any taxonomic recommendations, this paper adds to the growing evidence that L. mexicana and L. triangulum, as presently constituted, are not monophyletic groups.
2008 — Liner, E. A., and G. Casas-Andreu.Standard Spanish, English and Scientific Names of the Amphibians and Reptiles of Mexico. 2nd edition. SSAR Herpetological Circular No. 38. 162 pp. Surprisingly, the authors follow the lead of Hilken & Schlepper (1998) in resurrecting subspecies for L. mexicana (greeri, mexicana, and “thayerii“) and L. alterna, despite the lack of any supporting evidence.
2008 — Crother, B. I. (ed). Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. 6th edition. SSAR Herpetological Circular No. 37. 84 pp. In this edition of the N American checklist, the authors reconsidered their previous view of subspecies recognition in L. alterna, now regarding that species as monotypic.
2014 — Ruane, S., R. W. Bryson, Jr., R. A. Pyron, and F. T. Burbrink. Coalescent species delimitation in milksnakes (genus Lampropeltis) and impacts on phylogenetic comparative analyses. Systematic Biology 63(2):231–250. Although focused on a phylogenetic study of the Lampropeltis triangulum complex, this work also included samples of alterna, mexicana (inclusive of greeri and mexicana, but not leonis), ruthveni, and webbi, as well as zonata, pyromelana, and knoblochi. Importantly, this work confirmed that 1) webbi probably belongs in a mexicana group rather than allied with pyromelana, and appears to be the sister species to ruthveni; 2) alterna is NOT nested within triangulum, a question that arose during earlier studies based on mtDNA, but instead belongs to a clade consisting of mexicana, ruthveni, and webbi; 3) a “mexicana group” (at least based on the species sampled here) is a monophyletic lineage, and forms a sister-group relationship with the mountain kingsnakes (pyromelana, knoblochi, zonata). They also found genetic evidence for historical hybridization (though at very low levels) between alterna and two lineages of L. triangulum. In general, their conclusions relative to mexicana-group species, based on both nuclear and mitochondrial gene sequences, corroborate older studies based on morphology.
2014 — Wallach, V., K. L. Williams, and J. Boundy. Snakes of the World: A Catalogue of Living and Extinct Species. CRC Press, Taylor & Francis Group, Boca Raton, Florida. In this catalogue of the world’s snakes, Wallach et al. treated greeri and leonis as synonyms of L. mexicana. They stated that alterna is probably a subspecies of L. mexicana, apparently based on a mis-reading of the phylogenetic tree published by Bryson et al. (2007).
2016 — Heimes, P. Herpetofauna Mexicana Vol. 1. Snakes of Mexico. Edition Chimaira, Frankfurt am Main, Germany. 575 pp. Recognized three subspecies of L. mexicana (greeri, mexicana, thayeri).
2017 — Figueroa, A., A. D. McKelvy, L. L. Grismer, C. D. Bell, and S. P. Lailvaux. A species-level phylogeny of extant snakes with description of a new colubrid subfamily and genus. PLoS ONE 11(9): e0161070. In a large-scale DNA study, L. webbi was recovered as sister to a knoblochi + pyromelana clade, and in turn this group was sister to a clade comprised of mexicana, ruthveni, and the tropical milksnakes. L. alterna was found to be part of a group containing northern milksnakes. These results are not congruent with other recent studies.
2017 — Chen, X., A. R. Lemmon, E. Moriarty Lemmon, R. A. Pyron, and F. T. Burbrink. Using phylogenomics to understand the link between biogeographic origins and regional diversification in ratsnakes. Molecular Phylogenetics and Evolution 111:206–218. L. webbi was recovered as sister to ruthveni + “mexicana” (in the broad sense), and alterna was found to be sister to the pyromelana + zonata clades.
2017 – Hansen, R. W., and G. T. Salmon. Distribution analysis, taxonomic updates, and conservation status of the Lampropeltis mexicana group (Serpentes: Colubridae). Mesoamerican Herpetology 4:700–758. Based on morphology, color pattern, and allopatric ranges, authors recognized six species-level taxa (and no subspecies): alterna, greeri, leonis, mexicana, ruthveni, webbi.