Museum specimens reveal a rare new characid fish genus, helping to refine the interrelationships of the Probolodini (Characidae: Stethaprioninae)

(Received 7 July 2021; accepted 23 September 2021) Two new characid fish species are described from the upper rio Tocantins basin, Chapada dos Veadeiros, Goiás State, Brazil. Both species were discovered among specimens in museum collections. Relationships of taxa were evaluated in a more comprehensive phylogenetic analysis utilizing the largest dataset available of molecular and morphological data for the family Characidae. The two species were recovered as sister species and described in a new genus, closely related to <i>Erythrocharax</i> and <i>Phycocharax</i>. <i>Dinotopterygium</i> gen. nov. is distinguished from all other characid genera by the unique combination of ten synapomorphies, including the unique anal-fin morphology with a small number of branched anal-fin rays (13-16). <i>Dinotopterygium uniodon</i> sp. nov. and <i>D. diodon</i> sp. nov. differ by the number of tooth series in the premaxillary bone (one or two) and number of tooth cusps (7 or 5). The additional phenotypic variation for a taxonomically informative character within the Characidae through the discovery of new forms has helped to refine the interrelationship of the tribe Probolodini (Characidae: Stethaprioninae). The discovery of these new and possibly critically endangered species emphasizes the importance of museum collections for understanding biodiversity past and present. http://zoobank.org/urn:lsid:zoobank.org:pub:E0FD8207-590B-4FF7-B9CA-FD481A7F8B0E

(2021年7月7日收稿；2021年9月23日录用) 本研究记述了采自巴西戈亚斯州韦阿代鲁斯高地托坎廷斯河上游流域的2个脂鲤科（Characidae）鱼类新种。两个新种均源自博物馆馆藏标本。本研究利用脂鲤科迄今规模最大的分子与形态学数据集，通过更全面的系统发育分析评估了类群间的系统发育关系。系统发育分析结果显示，这两个新种互为姐妹种，且隶属于一新属，该属与*Erythrocharax*及*Phycocharax*亲缘关系密切。*Dinotopterygium* gen. nov.（新属）可通过10项共有衍征的独特组合与脂鲤科其他所有属区分开来，其中包括具有13~16枚分支臀鳍鳍条的独特臀鳍形态。*Dinotopterygium uniodon* sp. nov.（新种）与*D. diodon* sp. nov.（新种）可通过前颌骨的齿列数（1列或2列）以及齿尖数（7个或5个）加以区分。本研究通过新类群的发现，为脂鲤科补充了一批具备分类学参考价值的表型变异特征，这有助于厘清原突脂鲤族（Probolodini，脂鲤科：胸脂鲤亚科Stethaprioninae）的系统发育亲缘关系。这两个新种可能属于极危物种，此次发现凸显了博物馆馆藏标本对于认识过去与现今生物多样性的重要价值。http://zoobank.org/urn:lsid:zoobank.org:pub:E0FD8207-590B-4FF7-B9CA-FD481A7F8B0E