Biogeography, systematics and conservation of a complex of seasonal killifishes species of the genus Hypsolebias Costa 2006 (Cyprinodontiformes: Rivulidae) from the Caatinga
Endangered species, Molecular phylogeny, Neotropical fishes, São Francisco River
In Brazil, the neotropical seasonal killifishes genus Hypsolebias can be found in temporary pools within the floodplains of the Cerrado and Caatinga hydrographic basins. Over the past two decades, Hypsolebias has undergone frequent taxonomic changes that have led to the recognition of new phylogenetic relationships, providing an investigative framework for the evolutionary biogeographic patterns of the genus. This study focuses on the species group Hypsolebias antenori in the Caatinga hydrographic basins, where allopatric or parapatric lineages exhibit intense sexual dimorphism. These lineages are identified by differences in the color patterns of male fins, as well as morphometric and meristic characters that distinguish them. Since its discovery in 1952, the species H. antenori was initially acknowledged to have a broad geographical distribution across the Pacoti, Jaguaribe, Apodi-Mossoró, and Piranhas-Açu river basins. Through an integrative taxonomy approach, three new species were diagnosed, and H. antenori was restricted to the Jaguaribe River basin. The recognition of the three new species required a new systematic proposal for the H. antenori group. While phylogenetic analyses of molecular delimitation reveal that the H. antenori group can be separated into three species complexes, chrono-phylogenetic reconstructions date the divergence time between them to the late Pliocene. These results allow for the suggestion of the conservation status of the new species and a discussion on whether the divergence time between the H. antenori complexes reflects synchronicity with geomorphological episodes that altered the paleocourse of the São Francisco River. This river's mouth was situated in the North Atlantic through hydrographic connections with the Parnaíba, Jaguaribe, and Piranhas-Açu river basins until the Neogene period.