Maxwell J. Bernt, Aaron H. Fronk, Kory M. Evans, James S. Albert
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引用次数: 0
摘要
第二性二形现象在鬼刀鱼(Gymnotiformes: Apteronotidae)中比较常见,有几个物种的雄鱼长着大大的长鼻(例如:Compsaraia samueli、Parapteronotus hasemani),而其它物种的下颌(Sternarchorhynchus spp.)或双颌(Sternarchogiton nattereri)则长着增大、突出的牙齿。在已知的 4 个 Sternarchogiton 物种中,迄今只有 S. nattereri 有性二形的报道。在这里,我们报告了另一个物种拉比阿特斯(S. labiatus),成熟雄性的牙盘和前下颌上有类似的增大外齿。我们记录了在秘鲁伊基托斯附近的纳奈河(río Nanay)高水位产卵季节采集的三个标本的这种情况。我们利用高分辨率 X 射线微计算机断层扫描技术对这种形态进行了分析。此外,我们还利用基因序列数据证明,长有外齿的标本在基因上与具有拉比托斯鱼表型的标本没有区别。最后,我们回顾并总结了目前对Apteronotidae性二态的认识。
Sexual Dimorphism in the Electric Knifefish Sternarchogiton labiatus (Gymnotiformes: Apteronotidae) with a Hypermorphic Snout and Oral Jaws
Secondary sexual dimorphism is relatively common in the ghost knifefishes (Gymnotiformes: Apteronotidae), with males of several species growing greatly elongated snouts (e.g., Compsaraia samueli, Parapteronotus hasemani), while others develop enlarged, protruding teeth on either the lower jaw (Sternarchorhynchus spp.) or both jaws (Sternarchogiton nattereri). Of the four known species of Sternarchogiton, sexual dimorphism has so far only been reported in S. nattereri. Here we report that in an additional species, S. labiatus, mature males possess similar enlarged, external teeth on the dentary and premaxilla. We document this condition in three specimens collected during the high-water spawning season from the río Nanay near Iquitos, Peru. We analyze this morphology using high-resolution X-ray microcomputed tomography. Additionally, we use genetic sequence data to demonstrate that specimens bearing external teeth are genetically indistinguishable from those with the phenotype of S. labiatus. Finally, we review and summarize the current knowledge of sexual dimorphism within the Apteronotidae.