Intraspecific Variation of One of the Oldest Litopterna (Mammalia), Protolipterna ellipsodontoides, and Redescription of the Species

Acknowledging intraspecific variation is an important part of a reliable species diagnoses. For mammalian taxonomy, tooth morphology is an especially important trait and, therefore, the morphological variability of these structures is also greatly significant. Here we describe all dental variation present for Protolipterna ellipsodontoides based on a sample of more than 500 teeth and provide a differential diagnoses distinguishing from its sister taxa. Initially, the sample was carefully observed under stereo microscope in order to indentify variable traits. Further variable features were also highlighted by a geometric morphometric analysis. We conducted statistic tests to make sure all sample belong to the same species and the single identity of the sample was recovered. A great deal of our results show that structures like the parastyle, hypocone, conular cristae and ectoflexus can show different degrees of development for the same species. The tooth outline may also show some variation in shape and proportions. Many of those features are used as characters of phylogenies, however the current results pointed that those traits are inadequate for this sort of study, as they are variable within a single species. Some accessory cusps were also found, but they have very low frequency. These traits, however, does not have a clear phylogenetic sign and should be not be unadvisedly used in any taxonomy or phylogenetic research. doi: 10.5710/AMGH.11.08.2019.3250