Psalidodon, Eigenmann, 1911

Nunes, Denis Bruno Santos Marques, Pontes, Alany Itala, Santos, Leandro Ferreira dos, Calado, Leonardo Luís, Barros-Neto, Luciano Freitas, Lustosa-Costa, Silvia Yasmin, Queiroz Lima, Sergio Maia & Jacobina, Uedson Pereira, 2024, DNA barcoding highlights taxonomic uncertainties and cryptic lineages of São Francisco River basin fishes, Neotropical Ichthyology 22 (4), pp. e 240059-e 240059 : e240059-240059

The case of SPLIT and MIXTURE in the species complexes of Psalidodon and Astyanax .

Our results identified emblematic cases involving the genera Astyanax and Psalidodon within the MATCH, SPLIT, and MIXTURE categories, mitigating the Linnaean deficiencies related to representatives of these genera. Three clusters and three BINs (SPLIT) were identified for Astyanax lacustris in the SFR basin, with two exclusives to the upper section and one spread across all four sections, revealing a high cryptic diversity in this nominal taxon. A single cluster and one BIN (MATCH) for A. cf. fasciatus , including an individual of P. fasciatus , demonstrate the confusion and lack of updates in the taxonomic nomenclature of this group. Recently, A. fasciatus was reclassified as P. fasciatus ( Terán et al., 2020) . Morphological studies indicate that this specific epithet should be applied only to specimens from the SFR, in accordance with the original description (Cuvier, 1819). However, Melo, Buckup (2006) reported a species complex, including A. fasciatus , occurring outside the São Francisco basin, in the Paraná river basin. Until a complete taxonomic revision is published, the valid epithet for these populations remains P. fasciatus .

On the other hand, a single BIN (MIXTURE) involved four species ( A. bimaculatus , A. cf. fasciatus , P. rivularis , and P. fasciatus ). However, Bayesian analyses and the two species delimitation methods, GMYC and ASAP, separated a cluster exclusively for P. rivularis from another that is shared with the other mentioned taxa. Recently, the genus Psalidodon was reestablished as a valid monophyletic genus by Terán et al. (2020). This genus includes many taxa previously classified as Astyanax , encompassing most species from the A. eigenmanniorum , A. fasciatus , A. scabripinnis , and A. dissimilis groups. In the SFR basin, P. rivularis and P. fasciatus still present confused identifications across different sections. Therefore, our data highlight significant challenges in taxonomy and the urgent need to revise the classifications related to these species in the São Francisco River basin ( Rossini et al., 2016; Terán et al., 2020).