Taxonomic review and interspecific relationships of Lebiasininae (Ostariophysi: Characiformes: Lebiasinidae)

The subfamily Lebiasininae has been traditionally divided into two genera: Lebiasina and Piabucina. Historically, such division has been contested due to the inconsistency of the diagnostic characters differring both genera. To investigate the relationships among the Lebiasininae and the validity of Lebiasina and Piabucina, 59 representatives of the Lebiasinidae were compared, as well as representatives of five other characiform families as additional outgroups. The phylogenetic analysis, including 208 characters, obtained from different morphological complexes, yielded six fundamental trees with 800 steps. The topologies obtained recover the monophyly of the Lebiasininae based in five synapomorphies (four exclusive): postero-dorsal margin of infraorbital 3 with a projection that excludes patrially or completelly the infraorbital 4 from the orbital rim; dorsal surface of the mesethmoid T shaped; postero-ventral margin of coracoid truncate, without a distinct posteriorly projected process; infraorbital ramus of latero-sensory canal extending onto the antorbital; caudal blotch present. On the other hand, the topologies refute the monophyly of Lebiasina and Piabucina, and their synonymy is formally proposed herein. The analysis also recovers the Lebiasinidae as a monophyletic assemblage (based in 20 synapomorhies, 12 exclusive) as well as all other subunities of the family. Gradual miniaturization events apparently associated with several reductive characters and the evolution of life strategies in Nannostomus and Pyrrhulinina are discussed. As a result of the taxonomic review, 19 of the 22 nominal species are considered valid and seven are described as new. Among them, there are three species so far identified as Lebiasina bimaculata. All species are redescribed, their distribution is extended and new diagnoses are proposed to each of them. Additionally, an identification key to the species (valid and new) is presented. (AU)