Revisão taxonômica e filogenia da tribo Compsurini (Characiformes: Characidae: Cheirodontinae)

• Ano de defesa: 2011
• Autor(a) principal: Jerep, Fernando Camargo
• Orientador(a): Malabarba, Luiz Roberto
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ZOOLOGIA; ICTIOLOGIA; PEIXES - TAXIONOMIA; FILOGENIA
• Link de acesso: http://hdl.handle.net/10923/5386

Compsurini is a tribe of Cheirodontinae known for hosting inseminating species, and also characterized by unusual morphological modifications related to the male sexual dimorphism. The tribe defined by Malabarba, Weitzman & Burns, was found to be monophyletic in the phylogeny of the Cheirodontinae (Malabarba, 1998), however the relationships among its members was unstable when new terminals were added to the analysis by Malabarba, whose search for characters was focused to the Cheirodontini. With the description of new species after Malabarba´s analysis and the discovery of eight possible new species to the tribe Compsurini, a phylogenetic analysis of Compsurini was developed with the aim of testing the monophyly of the tribe and elucidating the relationships among its members. A hypothesis of phylogenetic relationships of Compsurini was built through parsimony analysis under implied weights based on 278 characters including external morphology, osteology, miology and ultrastructure of spermatozoa. In this analysis, both Cheirodontinae and Compsurini were found to be monophyletic. The new synapomorphies supporting Compsurini are: 1) distance between mesethmoid lateral processes distal tips, equal or shorter than mesethmoid posterior region; 2) anal-fin hooks anteriorly directed, curved over lateral surface of the anal-fin ray; 3) anal-fin rays bearing hooks concentrated along distal half or distal third of their length; 4) anal fin more strongly pigmented along distal portion of branched anal-fin rays on mature males; 5) spermatozoa midpiece not truncated posteriorly, and citoplasmatic canal longer than the half length of nucleus; and 6) spermatozoa with numerous globular vesicles.In Compsurini, two new species from the Amazon basin without caudal-fin sexual dimorphism were found to be sister group of the remaining integrants of the tribe. The genera Kolpotocheirodon, Saccoderma, and Compsura, the latter with two new species, were found to be monophyletic in this analysis. The Central America species “Compsura” gorgonae, “Odontostilbe” dialeptura, and “Odontostilbe” mitoptera, formed a monophyletic clade, sister group of the trans-Andean genus Saccoderma, which synapomorphies are related to sexual dimorphism and spermatozoa ultrastructure, supporting the creation of a new genus to accommodate these three species hitherto kept in temporary genera. In the taxonomic revision carried out in parallel to the phylogenetic analysis, the genus Compsura was redescribed along with the description of two new species from rio Guaporé and rio Araguaia basins. The genus Macropsobrycon is redefined and here considered monotypic with M. uruguayanae as typespecies. Saccoderma is also redescribed and restricted to two valid species, S. hastata and S. melanostigma, and the species S. falcata and S. robusta, considered synonyms of S. hastata. Three genera and six new species of the tribe are described for the high portion of Amazonian tributaries, along with the proposal of a taxonomic key comprising all compsurin species. Finally, on the reanalysis of the morphology-based matrix of characters present in the literature for Characidae, “Macropsobrycon” xinguensis was found to be sister group of Leptobrycon jatuaranae (with the addition of those species), and thus, “M”. xinguensis is located to Leptobrycon.