Lampropeltis leonis

Formally described as Coronella leonis by Albert Günther in 1893 using the leonis phenotype. In 1924, Arthur Loveridge wrote a description for Lampropeltis thayeri based on the milksnake phase and the taxonomic confusion was on! Much like the gray-banded kingsnake (Lampropeltis alterna), Nuevo León kingsnakes have different color phases or phenotypes (called polymorphism by biologists) and the different color phases were not initially recognized as the same species. It took until leonis and milksnake phases were seen hatching from the same clutches to realize that these were most likely the same species. It wasn't until 2008 that this species was correctly recognized as L. leonis, and many hobbyists and scientists alike still lump them into the mexicana species. Steven Osborne first documented the recessive nature of the melanistic phase in 1982. Although found in the wild, the melanistic phase was never formally described as a separate species like the other 2 phases were.

The photo, taken by Robert Applegate, clearly shows the 3 main variants of the Nuevo León kingsnake. The melanistic phase is on the left, the leonis phase is on the right, and the milksnake phase is in the center. There are innumerable variations and intermediate phases between the leonis and milksnake phases. All 3 main color phases and intermediates have been documented in the wild (in fact they were the driver of much taxonomic confusion). Many captive leonis don't much resemble their wild ancestors anymore - there has been a concerted effort to line-breed these snakes. There are now spectacular captive animals that exhibit bright orange backgrounds, tiger striping, or clean white backgrounds. While these are lovely, I prefer to breed and revive the more natural-looking variants. There are no morphs in pure Nuevo León kingsnakes, unless you consider the naturally-occurring recessive melanistic form to be a "morph." Although albino animals can be found for sale, these animals are hybrids created by breeding leonis with other species. The amelanistic allele has never been documented in a pure leonis.

Entirely found in the country of Mexico, Nuevo León kingsnakes live in the northern Sierra Madre Oriental mountain range close to where it meets the Chihuahuan Desert. The eastern portion of the range receives more rainfall and therefore contains more and different vegetation than the drier western edge of its range. The range of this species does not seem to overlap with any closely related species, although L. leonis and L. alterna are known to inhabit the mountains on opposite sides of the city of Monterrey. L. greeri are their closest neighbors to the south. For a detailed treatise on the range and natural history of the entire Lampropeltis mexicana group, including L. leonis, please click the map to be directed to Robert Hansen and Gerard Salmon's excellent 2017 paper.

The color patterns of this species vary so much that they were long thought to be separate species until both leonis and milksnake phase animals were observed hatching from the same clutches. Add the naturally-occurring melanistic animals to the mix, and you can see the problem for taxonomists. Then Nuevo León kingsnakes were thought to be merely a subspecies of Lampropeltis mexicana and lumped in with that taxon. Currently they are established as their own species. Interestingly, genetic studies have nested L. leonis within and between L. alterna (the gray-banded kingsnake) specimens! More data and more modern techniques need to be applied to truly discern the relationships between leonis, alterna, mexicana, greeri, and even the milksnake L. triangulum. The phylogeny is from Bryson's thesis on this matter, and links to his work. This work was done when L. leonis was known as L. m. thayeri. Research by Bryson and others suggest that leonis belong to a "northern clade" of Lampropeltis that includes L. alterna, L. triangulum celaenops (New Mexico milksnake), and L. t. gentilis (Central Plains milksnake) with the relationships unresolved, particularly between L. leonis and L. alterna.

Nuevo León kingsnakes max out around 44 inches in length, although most are smaller. The adults in my collection average 34-36 inches and around 250-300 grams. I have had adults top out as small as 25 inches and as large as 41 inches in my collection. This is an ideal size - they never need more than an adult mouse as a prey item or larger than a 20-gallon tank or 35 quart tub as a home. Biting, other than as the tiniest of hatchlings, is really not in their defensive repertoire. I've never received a bite from a leonis more than 6 weeks old in 25 years of keeping them, even as a feeding response. Nervous individuals may rattle their tails or musk when approached or picked up. Most grow out of this behavior with time can consistent handling although some remain nervous. In hand, they behave like other kingsnakes - active, inquisitive, exploring.