Phylogenetic relationships of new taxa support repeated pelvic fin loss in mountain catfishes from southern Brazil (Siluriformes: Trichomycteridae)

Abstract

The presence of paired appendages supported by endoskeleton elements is primarily shared by all gnathostomes, but secondarily lost in different lineages. Absence of pelvic fin and girdle is a condition relatively rare among trichomycterine catfishes, but a recent morphological study suggest that pelvic loss have occurred independently within the genus Cambeva. Herein we perform a molecular phylogenetic analysis encompassing all the five pelvic-less species of Cambeva, including two that are new: Cambeva podostemophila Costa, Feltrin & Katz sp. nov., which is supported by molecular and morphological data as sister to Cambeva poikilos, a species with well-developed pelvic fin and girdle; and Cambeva tourensis Costa, Feltrin & Katz sp. nov., that is sister to Cambeva flavopicta, another pelvic-less species. The ancestral character state reconstruction indicates that pelvic-fin loss occurred four times independently in Cambeva. Field observations indicated that C. podostemophila is closely associated to the podostemacean aquatic herb Podostemum rutifolium, consisting of the first record of trichomycterid–podostemacean association.