Nogueira Acácio F, Langeani Francisco, Netto-Ferreira André L
Programa de Pós-Graduação em Zoologia, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil.
Laboratório de Ictiologia, Departamento de Zoologia e Botânica, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), São Jose do Rio Preto, Brazil.
J Fish Biol. 2019 May;94(5):798-803. doi: 10.1111/jfb.13972. Epub 2019 Apr 8.
Hemiodus bimaculatus sp. nov., is described from tributaries of the Rio Juruena and Rio Teles Pires in the upper Rio Tapajós basin. The new species is diagnosed from most congeners, except Hemiodus jatuarana, by having a conspicuous circular or horizontally elongate dark blotch on the caudal peduncle (v. inconspicuous in H. iratapuru and absent in the other species). The new species differs from H. jatuarana by having a round midlateral spot on the flank (v. absent in H. jatuarana), 98-121 perforated scales in the lateral line (v. 66-72 in H. jatuarana), 23-28 scale series above and 14-19 below lateral line (v. 12-13 above and 6-7 below in H. jatuarana). Hemiodus bimaculatus is hypothesised to be related to species of the H. microlepis group, from which it also differs by having 11-25 epibranchial (v. 26-34 in H. argenteus, 29-39 in H. microlepis, 21-42 in H. orthonops and 27-35 in H. parnaguae) and 18-31 ceratobranchial (v. 38-50 in H. argenteus, 43-58 in H. microlepis, 32-52 in H. orthonops and 34-48 in H. parnaguae) gill rakers in the first arch.
新物种双线半齿脂鲤（Hemiodus bimaculatus sp. nov.）是在亚马孙河支流塔帕若斯河上游流域的茹鲁埃纳河和特莱斯皮里斯河支流中发现并描述的。除了雅图阿拉纳半齿脂鲤（Hemiodus jatuarana）外，该新物种与大多数同属物种的区别在于其尾柄上有明显的圆形或横向拉长的黑斑（伊拉塔普鲁半齿脂鲤（H. iratapuru）的黑斑不明显，其他物种则没有）。该新物种与雅图阿拉纳半齿脂鲤的区别在于其体侧中部有一个圆形斑点（雅图阿拉纳半齿脂鲤没有），侧线有98 - 121个穿孔鳞片（雅图阿拉纳半齿脂鲤有66 - 72个），侧线上方有23 - 28排鳞片，下方有14 - 19排鳞片（雅图阿拉纳半齿脂鲤上方有12 - 13排，下方有6 - 7排）。双线半齿脂鲤被认为与小鳞半齿脂鲤（H. microlepis）种群的物种有关，但它也与之不同，其第一鳃弓上有11 - 25个上鳃耙（银半齿脂鲤（H. argenteus）有26 - 34个，小鳞半齿脂鲤有29 - 39个，直眼半齿脂鲤（H. orthonops）有21 - 42个，帕尔纳瓜半齿脂鲤（H. parnaguae）有27 - 35个）和18 - 31个角鳃耙（银半齿脂鲤有38 - 50个，小鳞半齿脂鲤有43 - 58个，直眼半齿脂鲤有32 - 52个，帕尔纳瓜半齿脂鲤有34 - 48个）。
