A new study; ”Sequence-based molecular phylogenetics and phylogeography of the American box turtles (Terrapene spp.) with support from DNA barcoding” by Bradley T. Martina, Neil P. Bernsteinb, Roger D. Birkheadc, Jim F. Koukla, Steven M. Mussmannd and John S. Placyk Jr. has studied the DNA of all species and sub species of box turtles except Terrapene nelsoni klauberi. The study that was published in Molecular Phylogenetics and Evolution Volume 68, Issue 1, July 2013, Pages 119–134 can be found here and show that DNA evidence suggest that the species in the genus Terrapene should be revised.
The most important findings of the new study were:
- Terrapene ornata ornata and T. o. luteola shows no genetic difference and should be considered the same subspecies. The combined species should be known as Terrapene ornata
- T. c. triunguis (Three-toed box turtle) is to be considered a separate species (suggested name Terrapene mexicana) and not a subspecies of T. carolina due to a higher than 2% genetic difference between the species. The Mexican box turtle, T. carolina mexicana and Yucatán box turtle, T. carolina yucatana should be considered sub-species of the new Terrapene mexicana and should be called T. m. mexicana and T. m. yucatana respectively.
- Terrapene nelsoni was confirmed to be the sister taxon of T. ornata. Ie they are very closely related but still separate species.
- The study was not able to produce any conclusive results for T. carolina bauri, T. c. major, and T. coahuila
The findings of this study are very important since they will help conservation work that is species specific. The results of the study is a suggested revision of the genus Terrapene and until such time that these revisions are adopted the old names will still be valid. A revision do however seem likely so it might be worth memorizing these new names and consider them synonyms until a decision is made on whether to revise the genus or not.
If you would like to know more I recommend you read the study (available here).