Fish fauna of moderate altitude from first order stream in upper Rio Machado, Rondônia, Brazil

This study represents an inventory of fish collected in a first order tributary of the Igarapé Piracolina at Chapada dos Parecis, upper Rio Machado drainage, Rio Madeira basin, Vilhena, Rondônia, Brazil. The sampled stream is located in moderate altitudes (570-590) m above sea level and it is the type locality of five recently described species. Through fieldwork carried out in four fieldtrips between 2014 and 2015, 966 specimens were captured belonging to 18 species, distributed in nine families and four orders. Most of these species have a restricted distribution in the upper Rio Machado. Characidae was the most representative family both in number of species and specimens. One species is recognized as new and endemic to the region, and belong to the genus Pyrrhulina (Lebiasinidae), while five other species (Ancistrus verecundus, Bryconops piracolina, Hyphessobrycon lucenorum, Moenkhausia cambacica, and M. parecis) are also possibly endemic to the upper Rio Machado basin. In this scenario, our results provide relevant data for the establishment of guiding policies, management decisions and bases for conservation actions in moderate altitude areas of the Amazon basin.