Synopsis and taxonomic revision of three genera in the snake tribe Sonorini

ABSTRACT

Delimiting species is a crucial goal of integrative biology, and yet can be misled by homoplasy and high levels of morphological variation. The snake tribe Sonorini contains three genera that have long confounded taxonomists: Chilomeniscus, Chionactis and Sonora. Dynamic colour evolution in this group, including rampant geographic variation in colour and colour polymorphism, has led to a chaotic taxonomy. We used mitochondrial and high-throughput nuclear data (ddRADseq) and complete taxonomic sampling of each genus to reconstruct phylogenetic relationships and systematically revise the genus. Our research revealed that Sonora is paraphyletic with regards to Chilomeniscus and Chionactis and that at least one species (S. semiannulata) is paraphyletic with respect to at least one other recognized species. Additionally, we found substantial undescribed genetic diversity within multiple species which is incongruent with morphological variation in coloration. Accordingly, we proposed synonymizing Chionactis and Chilomeniscus with Sonora, which has taxonomic priority over both genera. As we found genetic evidence that supported some of the historically delimited diversity within multiple taxa, we revised species-level taxonomy accordingly. This new taxonomy recognizes a revised genus of Sonora that contains 15 species of diminutive and often brightly coloured snakes that are distributed from central Mexico to north-western USA.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:45A553D8-6435-4E0A-84ED-DF31E2CCD872

KEYWORDS:

• Sonora
• Chilomeniscus
• Chionactis
• Sonora semiannulata

Acknowledgements

We thank the University of Texas-Arlington Herpetology graduate students, the Texas Herpetological Society (THS), and the Kansas Herpetological Society (KHS) for tissue donation, specimen collection, and logistical assistance. Our gratitude is extended to the staff and curators at the following museum collections for access to specimens: Museum of Vertebrate Zoology at the University of California Berkeley, California Academy of Sciences, San Diego Natural History Museum, Arizona State University, University of Arizona, New Mexico State University, Museum of Southwestern Biology at the University of New Mexico, the Texas Natural History Collection at The University of Texas at Austin, the Biodiversity Collections at the University of Texas - El Paso, the Amphibian and Reptile Diversity Research Center at the University of Texas - Arlington, Sam Noble Museum at the University of Oklahoma, the Biodiversity Institute and Natural History Museum at the University of Kansas, and the Sternberg Museum of Natural History at Fort Hayes State University. We especially thank Travis J. Laduc, Curtis Schmidt, and Carl J. Franklin for curatorial assistance. We also thank Sonal Singhal for bioinformatics assistance. This project was funded by the Theodore Roosevelt Memorial Fund from the American Museum of Natural History to C.L. Cox, as well as a Systematics Research Fund Award from The Linnaean Society and an NSF Postdoctoral Fellowship in Biology (DBI-0906046) to A.R. Davis (Rabosky).

Data availability statement

Data for this study is archived in the Dryad Data Repository (https://datadryad.org/). Mitochondrial sequence data are available at https:doi.org:10.5061/dryad.vt00811. ddRADseq sequence data are available at https://doi.org/10.5061/dryad.8jt2694.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Theodore Roosevelt Memorial Fund from the American Museum of Natural History; The Linnaean Society; NSF Postdoctoral Fellowship [DBI-0906046].