A new early on-line study examines reports unrecognized diversity in the milksnake (Lampropeltis triangulum) Coalescent species delimitation indicates that L. triangulum is not monophyletic and that there are multiple species of milksnake, which increases the known species diversity in the genus Lampropeltis by 40%. Both genealogical and temporal discordance occurs between gene trees and the species tree, with evidence that mtDNA introgression is a main factor. The highlights of the study include the following.
1) Lampropeltis triangulum: from Ontario, Canada along the Georgian Bay, throughout southern Quebec, and east of Lake Huron, extending throughout southern Maine, south through New England and New York to North Carolina and the extreme northern Alabama and Georgia and west to eastern Minnesota. Subspecies synonymized under L. triangulum would include L. t. syspila and any suspected “intergrades” that occur in Alabama, Indiana, Iowa, Illinois, Kentucky, Missouri, Mississippi, Tennessee, and possibly Arkansas north of the Arkansas River, and some milksnakes that have fallen under the subspecies L. t. amaura in northeastern Louisiana (specifically in La Salle Parish).
2) Lampropeltis gentilis: Found from the Panhandle of northern Texas, western Oklahoma, central and western Kansas, eastern Colorado, and south-central and southwestern Nebraska. The range of L. gentilis also includes the ranges of the following subspecies, which are synonymized with L. gentilis: L. t. amaura (part), found in eastern Texas, southeastern Oklahoma, Louisiana west of the Mississippi River, and southern Arkansas; L. t. celaenops in southeastern Arizona, New Mexico and adjacent eastern Texas; L. t. multistriata, found in northwestern Nebraska, the western half North Dakota, northern Wyoming, and southern Montana; and L. t. taylori found in Utah, northern Arizona, and western Colorado. In addition, L. gentilis includes L. t. annulata from at least central Texas and L. t. syspila from Nebraska, Kansas, and Oklahoma.
3) Lampropeltis elapsoides: southeastern US as far north as Virginia and Kentucky east of the Mississippi River and in eastern Louisiana. Suspected “intergrades” with L. triangulum from eastern Virginia to southern New Jersey are likely L. triangulum and not hybrids.
4) Lampropeltis annulata: Mexican states of Nuevo León, Querétaro, and Tamaulipas. It is likely that this species is also found in Coahuila, eastern San Luis Potosi, and Hidalgo. Subspecies synonymized with L. annulata include L. t. dixoni.
5) Lampropeltis polyzona: Mexican states of Colima, Guerrero, Hidalgo, Jalisco, Puebla, Michoacán, Oaxaca, Sinaloa, Sonora, and Veracruz. It is likely that this species is also found in Guanajuato, Morelos, and Nayarit, and western San Luis Potosí.
6) Lampropeltis abnorma: southern Veracruz and southeastern Guerrero ranging south through Nicaragua, Honduras, and western Costa Rica. This species is possibly in southern Oaxaca, and likely Campeche, Chiapas, Quintana Roo, Tabasco, and Yucatan as well as Belize and El Salvador. . Subspecies synonymized with L. abnorma include L. t. blanchardi, L. t. hondurensis, L. t. oligozona and L. t. stuarti.
7) Lampropeltis micropholis: eastern Costa Rica, throughout Panama, and south to Ecuador. It is likely found in Colombia and possibly Venezuela. Subspecies synonymized with L. micropholis include L. t. gaigeae and L. t. andesiana.
Sara Ruane, Robert W. Bryson, Jr., R. Alexander Pyron, and Frank T. Burbrink (2014) Coalescent Species Delimitation in Milksnakes (genus Lampropeltis) and Impacts on Phylogenetic Comparative Analyses. Systematic Biology early on-line December 10, 2013 doi:10.1093/sysbio/syt099