Characiformes is one of the most diverse orders in Actinopterygii, representing the richest order in the Amazon basin. Among the genera distributed in this biome, we highlight Priocharax, currently with five valid species of miniature fishes (i.e., reaching up to 26 mm Standard Length), all of which retain the larval pectoral fin in the adults. Preliminary morphological, osteological and molecular data indicate the existence of an undescribed species of Priocharax in the region of rio Purus, near its mouth. Therefore, the proposed project aims at a detail analysis of material available in collections and from a recent fieldtrip based on meristic, morphometric and osteological data. Meristic and morphometric data will be accessed with the aid of a stereomiscroscope connected to a computer, with the use of morphometric tools of the Zen software. Some specimens will be cleared and stained for accessing the osteological characters. Comparative analyses with congeners will also be done based on information in the literature as well as direct examination of specimens already available for this study, including types. Results obtained will be joined to DNA barcode data provided by a collaborating research group in the context of project JP-FAPESP (2017/1970-4). The proposed taxonomic study of Priocharax sp. aims at a more precise diagnosis of this putative new species to describe it. This will lead to the better understanding of the diversity in the genus, as well as the Amazonian ichthyofauna in general.
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