A new species of Knodus (Characiformes: Characidae: Stevardiinae) from the rio Aripuanã, rio Madeira basin, Brazil

ABSTRACT A new species of the characid genus Knodus is described from the rio Aripuanã (rio Madeira basin). It can be distinguished from its congeners by its very low body depth, the presence of tri- to pentacuspid teeth on the outer premaxillary series, with the median cuspid larger than the lateral ones, the teeth of the inner premaxillary series pentacuspid, distinctly larger than those of the outer series, the maxillary teeth tri- to pentacuspid, with the median cusp slightly larger than the lateral ones, the four anteriormost dentary teeth pentacuspid, the smaller posterior teeth tri- to pentacuspid, a complete lateral line with 36-38 scales, 3 longitudinal scale series from pelvic fin origin to lateral line, and 11-12 circumpeduncular scales. The new species is also compared to incertae sedis species of ‘Bryconamericus’ from northern South America since phylogenetic studies suggest a closer relationship of those species with Knodus.

摘要：本研究描述了采自阿里普万河（马代拉河流域）的脂鲤科克诺脂鲤属（Knodus）一新种。该新种可通过以下特征与同属物种相区分：体高极低；外列前颌骨齿为3至5齿尖型，其中央齿尖显著大于侧齿尖；内列前颌骨齿为5齿尖型，且明显大于外列齿；上颌齿为3至5齿尖型，中央齿尖略大于侧齿尖；下颌最前方4枚齿为5齿尖型，后方较小的齿为3至5齿尖型；侧线完全，具36~38枚鳞片；腹鳍起点至侧线的纵向鳞列数为3；尾柄周鳞数为11~12。鉴于系统发育研究表明这些‘布氏脂鲤属（Bryconamericus）’的分类未定物种与克诺脂鲤属物种的亲缘关系更为密切，本研究同时将该新种与南美洲北部的‘布氏脂鲤属（Bryconamericus）’分类未定物种进行了比对。