From the mud to the tree: phylogeny of Austrolebias killifishes, new generic structure and description of a new species (Cyprinodontiformes: Rivulidae)

Abstract

Killifishes (Cyprinodontiformes) are a group of fish that include high proportion of small-bodied species living in seasonal aquatic habitats, with narrow geographic distributions and high human impact, that are among the most vulnerable vertebrates in the Neotropical region with nearly half of its species in threat categories. Herein we propose a new phylogenetic hypothesis of the Rivulidae genus Austrolebias, based on 10 different genes (6 nuclear and 4 mitochondrial) and 191 morphological characters including 90% of the total valid species of this genus. An updated definition and diagnosis of the existing subgenera of Austrolebias is provided and these are erected to genera. Also, 4 new genera are erected to accommodate the group´s taxonomy to the current phylogenetic hypothesis. Additionally, we describe a new species, Argolebias guarani, diagnosed by a unique color pattern, from a seasonal pond, at Middle Paraná River basin. This is an addition reinforcing this area as a biodiversity hotspot of endemicity that highlights the conservation importance of this region. Data on the ontogenetic changes in color pattern, egg’s chorion ornamentation and ecology of this species are also provided.