Andrade M. C. auteur aut IRD Jégu Michel auteur aut IRD Buckup P. A. auteur aut IRD Netto-Ferreira A. L. auteur aut IRD text journalArticle eng text/pdf born digital access Myleus pachyodus, a new serrasalmid species, is described from the Rio Teles Pires and Rio Jamanxim, both tributaries of the Rio Tapajos in Mato Grosso and Para states, Brazil. The new species differs from all congeners by having a remarkable ontogenetic thickening of the teeth shifting from slender incisiform in juveniles to thick bulky teeth at standard length100mm, whereas congeners present slender, antero-posteriorly flat teeth throughout all life stages. The new species further differs from congeners by having 18-20 branched dorsal-fin rays, by the lack of a diastema between contralateral outer series of premaxillary teeth and by the presence of 16-25 prepelvic spines, with the anteriormost spine never reaching the vertical through the pectoral-fin origin. specialized Neotropical Ostariophysi rheophilous fish taxonomy threatened fish BRESIL MATO GROSSO PARA RIO TAPAJOS BASSIN RIO TELES PIRES RIO JAMANXIM 034 92 6 1902-1914 2018 0022-1112 https://www.documentation.ird.fr/hor/fdi:010073146 10.1111/jfb.13628 0022-1112 [F B010073146] https://www.documentation.ird.fr/hor/fdi:010073146 https://www.documentation.ird.fr/intranet/publi/2018/07/010073146.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2018-09-03 2018-09-03 fdi:010073146 fre