Cryptic diversity and recent diversification in the <i>Pyrrhulina australis</i> species complex (Characiformes, Lebiasinidae) revealed by mitochondrial <scp>DNA</scp>

Pyrrhulina australis Eigenmann & Kennedy, 1903, is widely distributed across the main hydrographic basins of South America. The taxonomic integrity of this species is nevertheless challenged by the lack of clear diagnostic characters, its marked geographic variation and the morphological overlap with its congeners. In this context, the present study investigated the genetic diversity of the P. australis group (P. australis, Pyrrhulina marilynae and Pyrrhulina vittata), using sequences of the mitochondrial Cytochrome Oxidase I gene to delimit evolutionary lineages and provide insights into biogeographic patterns and divergence times. The molecular delimitation analyses (Automatic Barcode Gap Discovery [ABGD], Assemble Species by Automatic Partitioning [ASAP], Bayesian Poisson Tree Processes (bPTP), multi-rate Poisson Tree Processes [mPTP], General Mixed Yule Coalescent [GMYC] and Poisson Tree Processes [PTP]) revealed 12 consensual MOTUs, which represent a complex of cryptic species revealed under the nominal name P. australis, with widely distributed lineages. Divergence time estimates indicate a recent evolutionary history for the group, occurring between the late Pliocene and the Pleistocene. The results reveal a surprising level of diversity within P. australis and provide unprecedented discussions on the biogeographic patterns of the group.