Costa Wilson J E M, Mattos José Leonardo O, Katz Axel M
Laboratory of Systematics and Evolution of Teleost Fishes, Institute of Biology, Federal University of Rio de Janeiro, Caixa Postal 68049, CEP 21941-971, Rio de Janeiro, Brazil. E-mail:
Zool Stud. 2021 Jul 30;60:e43. doi: 10.6620/ZS.2021.60-43. eCollection 2021.
The Trichomycterinae is among the most diverse catfish groups in the world, with interesting ecological specializations; however, the taxonomy of Trichomycterinae is still problematic, mainly due to unclear limits and diagnoses of the eight included genera. Herein we infer the phylogenetic position and generic placement of , a recently described species from north-eastern Brazil, with unique morphological features among congeners. A multigene analysis including fragments of two nuclear and two mitochondrial genes (total of 2974 bp) for 53 trichomycterine taxa and three outgroups clearly supports inclusion of in , a trichomycterine genus containing 29 valid species, which is corroborated by osteological characters. An examination of osteological characters used to diagnose in its original description indicates that a rudimentary or absent posterior cranial fontanel is synapomorphic for , but this is reversed in ; an anteriorly directed antero-lateral extremity of the sphenotic-prootic-pterosphenoid complex and a narrow and long lateral process of the parurohyal are synapomorphic for , but homoplastically occurring in other trichomycterids; and the presence of a deep medial concavity on the autopalatine is ambiguous to diagnose by occurring in other closely related trichomycterine taxa. is also distinguishable from other trichomycterines by a unique shape of the metapterygoid and by a reduced number of ribs. The analysis supports a clade, comprising and , that is endemic to the Chapada Diamantina, in the semiarid Caatinga of north-eastern Brazil, reinforcing the importance of this region for trichomycterid diversification. By integrating molecular analysis and comparative morphology, the present study provides a more solid basis for delimiting , creating a better taxonomical resolution of the Trichomycterinae, although much more research is necessary to reach a consistent generic classification for the entire subfamily.
毛鼻鲶亚科是世界上鲶鱼种类最多样化的类群之一，具有有趣的生态特化现象；然而，毛鼻鲶亚科的分类学仍然存在问题，主要是由于所包含的八个属的界限和诊断不明确。在此，我们推断了一种最近在巴西东北部描述的具有独特形态特征的物种在系统发育中的位置和属的归属。对53个毛鼻鲶亚科分类单元和三个外类群进行的多基因分析，包括两个核基因和两个线粒体基因的片段（共2974个碱基对），明确支持将该物种归入包含29个有效物种的毛鼻鲶属，这一点也得到了骨学特征的证实。对该物种原始描述中用于诊断的骨学特征进行检查表明，后颅囟发育不全或缺失是该属的共有衍征，但在该物种中则相反；蝶耳骨 - 前耳骨 - 翼蝶骨复合体的前外侧末端向前以及副尾舌骨的侧突窄而长是该属的共有衍征，但在其他毛鼻鲶科鱼类中也有趋同出现的情况；自腭骨上存在深的内侧凹陷对于该物种的诊断并不明确，因为在其他密切相关的毛鼻鲶亚科分类单元中也有出现。该物种还通过独特的后翼骨形状和减少的肋骨数量与其他毛鼻鲶亚科鱼类区分开来。分析支持一个分支，包括该物种和另一种，它们是巴西东北部半干旱卡廷加地区钻石山的特有物种，这凸显了该地区对毛鼻鲶科鱼类多样化的重要性。通过整合分子分析和比较形态学，本研究为界定该物种提供了更坚实的基础，对毛鼻鲶亚科的分类学有了更好的分辨率，尽管要对整个亚科达成一致的属分类还需要更多的研究。
