The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (Günther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

中文翻译：

---

五个尼罗河象鱼的第一个细胞遗传学信息以及Mormyridae（Osteoglossiformes）家族的祖先核型问题。

象鱼科Mormyridae是原始硬骨鱼进化枝Osteoglossomorpha的最多样化的谱系，分布在除南极洲和欧洲以外的所有大洲的内陆水域。mormyridae科是非洲特有的，包括22属和近230种。甲虫的进化辐射很可能应归因于它们产生和接收微弱电信号的能力。最新的细胞遗传学研究表明，在九种被调查的象鱼物种和属（每个属中研究一种单一物种）之间，存在明显的核型差异。在本研究中，首次描述了从埃塞俄比亚西南部的White Nile系统收集的代表5个蠕虫属（5个未开发物种）的5个物种的核型。结果表明二倍体染色体和基本数存在很大差异：黑短毛霉（Günther，1866）为2n = 48和FN = 54，Pycyphomyrus petherici（Boulenger，1898）为2n = 50和FN = 72，2n = 50和FN在河马（Hippopotamyrus pictus）中为78（Marcusen，1864），在cyprinoides（Linnaeus，1758）中为2n = 50，FN = 76，在Mormyrops anguilloides（Linnaeus，1758）中为2n = 52和FN = 52。后一种物种的核型结构似乎与该家族的祖先条件接近。该假说是根据有关核型的核型多样性和系统发育的可用数据进行讨论的。在马库里乌斯（Marcusenius cyprinoides）中（Linnaeus，1758）2n = 50和FN = 76，在Mormyrops anguilloides（Linnaeus，1758）中2n = 52和FN = 52。后一种物种的核型结构似乎与该家族的祖先条件接近。该假说是根据有关核型的核型多样性和系统发育的可用数据进行讨论的。在马库里乌斯（Marcusenius cyprinoides）中（Linnaeus，1758）2n = 50和FN = 76，在Mormyrops anguilloides（Linnaeus，1758）中2n = 52和FN = 52。后一种物种的核型结构似乎与该家族的祖先条件接近。该假说是根据有关核型的核型多样性和系统发育的可用数据进行讨论的。