Reconquering the water

The Cercosaurini tribe stands out from other Gymnophthalmidae lizards for including several species with morphological adaptations to aquatic lifestyle (“Crocodile-Like Morphology” – CLM). Recent molecular phylogenies of Cercosaurini demonstrated the paraphyly of CLM species, implicitly suggesting that adaptations to the aquatic life evolved more than once. However, CLM species have remained poorly sampled, and a number of uncertainties persist, such as the monophyly of Neusticurus and the placement of Potamites apodemus within the tribe. Based on a more extensive molecular and morphological data set, we propose a phylogenetic hypothesis for Neusticurus and investigate, for the first time, the phylogenetic position of P. apodemus. We recovered a monophyletic Neusticurus clade; however, Neusticurus rudis as currently understood was recovered as paraphyletic, with two lineages that also show consistent morphological diagnosis; as a result, we resurrect and provide a taxonomic redescription of Neusticurus surinamensis Müller,. Moreover, because P. apodemus was recovered as sister to all other Echinosaura, we propose a new combination for this species (Echinosaura apodema). We also review the distribution of Neusticurus species, offering a comprehensive view of their biogeography. Lastly, our ancestral character reconstruction and dating analyses indicate that the CLM phenotype evolved four times independently during Cercosaurini′s evolutionary history. We hypothesize that the CLM phenotype and subsequent adaptation to aquatic life may be linked to the development of the Pebas Lake in western Amazonia during the Miocene.