Taxonomic Turmoil: Using ddRAD Data to Resolve Taxonomic Discrepancies within the Genus Characodon (Cyprinodontiformes: Goodeidae)

Characodon (Cyprinodontiformes: Goodeidae) is a highly imperiled genus of fishes fromnorthern Mexico that consists of two extant species (C. lateralis and C. audax), as well as a thirdextinct species (C. garmani), only known from the holotype. There are uncertainties in regard tothe type localities for C. lateralis and C. garmani, making taxonomic revisions challenging. Wegathered ddRADSeq data to generate a genome-wide data set for populations of Characodonacross the range. Our population genetic (F ST , DAPC, PCA, sNMF) and phylogenetic analyses (ML)recovered three major groups/clades within Characodon, including one group corresponding toabove the falls, and two separate groups from below the falls. Species delimitation analysesusing BPP confirm the existence of three groups. Therefore, we recognize four species withinCharacodon. We must continue to recognize C. garmani as we did not include samples in ourstudy and are therefore unable to re-assess its taxonomic status based on genetic data. Werecognize all other populations above the falls as C. audax due to issues associated with thetype locality and syntypes of C. lateralis. Finally, we recognize two undescribed species belowthe falls, Characodon sp. 1 (Los Berros-La Constancia) and Characodon sp. 2 (Amado Nervo) thatawait formal descriptions.