Abstract
A new species of Lycengraulis from the Amazon basin is described. Lycengraulis figueiredoi can be distinguished from L. grossidens by a short upper maxilla, its posterior margin not reaching the lower maxilla joint (vs. upper maxilla longer, its posterior margin reaching to or a little past of mandible joint). Lycengraulis figueiredoi can be distinguished also from L. poeyi by 26 to 31 anal-fin rays (vs. 21 to 23 anal-fin rays) and by 44 to 46 vertebrae (vs. 42 vertebrae), and from L. batesii by having the anal-fin origin at vertical through base of second to fifth dorsal-fin ray (vs. anal-fin origin at vertical through base of sixth to 10th dorsal-fin ray) and by 17-21 gill rakers on the lower branch of first gill arch (vs. 12–15 gill rakers on the lower branch of first gill arch). The new species occurs in the rio Purus, Negro, Trombetas and Solimões, in the Amazon basin, Brazil.