Using geometric morphometrics for integrative taxonomy: An examination of head shapes of milksnakes (genus Lampropeltis)

Species discovery and identification has long relied on traditional morphometric analyses, although molecular methods for species delimitation are becoming increasing popular and important. Despite an increase in studies that rely solely on molecular data to differentiate between species, additional evidence that supports genealogically-based species delimitation is desirable at least for field and museum identification of species and is part of an integrative approach to taxonomy. The present study uses geometric morphometric (GM) analyses to examine six species of milksnake (genus Lampropeltis) that have recently been delimited based on multilocus data in a coalescent framework. Landmarks are plotted onto the dorsal view of 487 specimens and canonical variate analysis (CVA) is used to determine whether the differences in head shape of these six species can be used to correctly classify specimens. For five of the six species, CVA accurately classifies individuals >70% of the time. The present study illustrates that, although GM-based analyses may not correctly differentiate between species 100% of the time, GM methods can be useful for detecting shape differences between species and help to corroborate species delimitation.