The African family Distichodontidae comprises 109 species in 16 genera. Up-to-date cytogenetic information was available for the only distichodontid species Distichodus affinis Günther, 1873. Here we report chromosome number and morphology in: Distichodus engycephalus Günther, 1864 (2n = 52, FN = 104), Ichthyborus besse (Joannis, 1835) (2n = 46, FN = 92), Nannocharax niloticus (Joannis, 1835) (2n = 54, FN = 106) and three taxa, Nannaethiops bleheri Géry et Zarske, 2003, Nannaethiops sp., and Neolebias unifasciatus Steindachner, 1894, that exhibit the same karyotypes (2n = 50, FN = 98). To confirm the Nannaethiops Günther, 1872 and Neolebias Steindachner, 1894 species identification, mt-DNA sequences of the two markers (COI and 16S rRNA) were obtained from karyotyped specimens and compared with the relevant sequences accessible from GenBank. The great prevalence of biarmed chromosomes (the karyotypes of most species contain exclusively biarmed chromosomes) is a distinctive characteristic of Distichodontidae and Cithariniformes as a whole.

中文翻译：

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非洲特有鱼类科 Distichodontidae（Cithariniformes、Osteichthyes）五个属的不同核型

 非洲 Distichodontidae 科包括 16 属 109 种。最新的细胞遗传学信息适用于唯一的二齿兽科物种 Distichodus affinis Günther, 1873。在这里，我们报告了染色体数量和形态：Distichodus engycephalus Günther, 1864 (2n = 52, FN = 104), Ichthyborus besse (Joannis, 1835) ）（2n = 46，FN = 92），Nannocharax niloticus（Joannis，1835）（2n = 54，FN = 106）和三个分类群，Nannaethiops bleheri Géry et Zarske，2003，Nannaethiops sp.和Neolebias unifasciatus Steindachner，1894，表现出相同的核型（2n = 50，FN = 98）。为了确认 Nannaethiops Günther, 1872 和 Neolebias Steindachner, 1894 的物种鉴定，从核型样本中获得了两个标记（COI 和 16S rRNA）的 mt-DNA 序列，并与 GenBank 中的相关序列进行了比较。双臂染色体的广泛存在（大多数物种的核型仅包含双臂染色体）是Distichodontidae和Cithariniformes作为一个整体的显着特征。