Resolving Questionable Records of Pituophis ruthveni (Louisiana Pinesnake)
Authors: Connor S. Adams, Josh B. Pierce, D. Craig Rudolph, Wade A. Ryberg, and Toby J. Hibbitts
Pituophis ruthveni (Louisiana Pinesnake) is considered one of the rarest snakes in North America. For that reason, P. ruthveni is not well represented in scientific collections, and each existing specimen is very important. Some museum records for the species are considered questionable or unverified, especially those that represent extralimital records or those from habitats not normally utilized by Louisiana Pinesnake. Clarifying these questionable Louisiana Pinesnake records will ultimately provide a better understanding of its historic and current distribution, which is necessary for listing decisions, critical-habitat designation, and overall conservation efforts for the species. To resolve this uncertainty, we performed a multivariate analysis using 13 morphological characters on 50 specimens representing 3 snake groups: (1) P. ruthveni (n = 23), (2) P. catenifer sayi (Bullsnake; n = 23), and (3) questionable or unverified snakes (n = 4). We included Bullsnake because they are sister to Louisiana Pinesnake genetically and also most morphologically similar. We identified all questionable records of Louisiana Pinesnake examined as Bullsnake. Blotch count, ventral-scale number, and scale-row number at mid-body were the most reliable characters for distinguishing between groups. These results have potential conservation implications for the species. The influence of these erroneous records could be substantial in future research and conservation of the species due to the relatively few known specimens of Louisiana Pinesnake. We recommend that the specimens we identified be annotated and considered erroneous records.