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Chromosome changes can perform an important role in speciation by acting as post-zygotic reproductive barriers. The Neotropical electric fish genus Brachyhypopomus (Gymnotiformes, Hypopomidae) has 28 described species, but cytogenetic data are hitherto available only for four of them. To understand karyotype evolution and investigate the possible role of chromosome changes in the diversification of this genus, we describe here the karyotype of eight species of Brachyhypopomus from a sympatric assemblage in the central Amazon basin. We analyzed cytogenetic data in the context of a phylogenetic reconstruction of the genus and known patterns of geographical distribution. We found a strong phylogenetic signal for chromosome number and noted that sympatric species have exclusive karyotypes. Additional insights into the role of chromosome changes in the diversification of Brachyhypopomus are discussed.

染色体变化可通过充当合子后生殖隔离屏障，在物种形成过程中发挥关键作用。新热带区电鱼短电鱼属（Brachyhypopomus，裸背电鳗目：低鳍电鱼科）目前已记述28个物种，但迄今仅4个物种拥有细胞遗传学数据。为厘清该属的核型演化规律，并探究染色体变化在其物种多样化进程中的潜在作用，本文对采自亚马孙中部盆地同域类群的8种短电鱼属物种的核型进行了描述。我们结合该属的系统发育重建结果与已知地理分布模式，对细胞遗传学数据展开分析。研究发现染色体数目存在显著的系统发育信号，且同域物种均拥有专属核型。本文还就染色体变化在短电鱼属物种多样化中的作用展开了进一步讨论。