Integrating morphological and molecular data in the taxonomic and phylogenetic study of the miniature fish Priocharax Weitzman & Vari (Teleostei, Characiformes, Characidae)

Abstract

The Neotropical region harbors the most diverse freshwater ichthyofauna in the world, with many diminutive forms. Miniature fishes are those whose adults do not grow over 26 mm of standard length and include more than 210 Neotropical species, a third in the family Characidae. Priocharax is a genus from the Amazon with three of the smallest characids known, characterized mainly by the retention of the larval pectoral fin in adults. Priocharax was proposed as closely related to the subfamily Heterocharacinae, but the relations among the genera in this subfamily are yet to be tested in light of new evidence including the molecular approach. The amount of samples of Priocharax in collections has considerably increased, revealing new records and morphological variations that allow recognizing additional undescribed species. However, due to its inherent fragility, freshly collected and adequately preserved samples are needed for a proper morphological study since old specimens deposited in museums lose scales, colour and decalcify, impeding a detailed morphological approach. I herein propose seven fieldtrips to localities of confirmed records of Priocharax in order to have properly preserved material for osteological and other morphological studies, compilation of a tissue collection of all species, in addition to photographs of the live fish and their localities. Tissue samples will be incorporated to others already available, allowing a DNA barcode study to complement the taxonomic investigation, and an approach using six molecular markers to access the phylogenetic relationships of Priocharax at intra- and intergeneric levels. (AU)