Tkach Vasyl V, Greiman Stephen E, Pulis Eric E, Brooks Daniel R, Bonilla Carlos Carrion
Department of Biology, University of North Dakota, Grand Forks, ND, USA.
Department of Biology, Georgia Southern University, Statesboro, GA, USA.
Parasitol Int. 2019 Jun;70:118-122. doi: 10.1016/j.parint.2019.02.003. Epub 2019 Feb 7.
The systematic position of Urotrema Braun, 1900 and the family Urotrematidae Poche, 1926 have always been controversial. Due to its unusual morphological characteristics, lack of knowledge of the life cycle or details of its excretory system, this family was placed within different higher taxonomic groups of digeneans. Despite being one of the most enigmatic digenean families in terms of its phylogenetic affinities, DNA sequence data for Urotrematidae were lacking. Here, we evaluate the phylogenetic relationships of Urotrema using newly obtained partial sequences of the 28S rRNA gene from Urotrema specimens collected in North, Central and South America including the type species U. scabridum Braun, 1900, as well as previously published sequences of digeneans. Our study has demonstrated that Urotrema is phylogenetically closest (100% branch support) to members of Parabascus Looss, 1907 belonging to the family Pleurogenidae Looss, 1899. Thus, the family Urotrematidae becomes a junior synonym of the Pleurogenidae. Urotrema forms a 100% supported clade among the Pleurogenidae, parasitic in warm-blooded vertebrates. However, the phylogenetic relationships and exact systematic position of the remaining 3 genera currently placed in the Urotrematidae remains unclear and requires additional studies as their allocation is mostly based on the terminal posterior position of the genital pore and cirrus-sac. According to our results the genus Parabascus appears to be paraphyletic and requires further detailed phylogenetic and morphological analyses.
1900年的糙殖吸虫属（Urotrema Braun）及1926年的糙殖吸虫科（Urotrematidae Poche）的系统位置一直存在争议。由于其形态特征异常，对其生命周期或排泄系统细节缺乏了解，该科被置于复殖吸虫纲的不同高级分类群中。尽管就其系统发育亲缘关系而言，糙殖吸虫科是最神秘的复殖吸虫科之一，但此前缺乏该科的DNA序列数据。在此，我们利用新获得的来自北美、中美和南美采集的糙殖吸虫标本的28S rRNA基因部分序列，包括模式种1900年的糙皮糙殖吸虫（U. scabridum Braun），以及之前发表的复殖吸虫序列，评估糙殖吸虫属的系统发育关系。我们的研究表明，糙殖吸虫在系统发育上与1907年的副巴斯吸虫属（Parabascus Looss）的成员最为接近（分支支持率100%），副巴斯吸虫属属于1899年的侧殖科（Pleurogenidae Looss）。因此，糙殖吸虫科成为侧殖科的次同物。糙殖吸虫在侧殖科中形成一个得到100%支持的分支，寄生于温血脊椎动物。然而，目前置于糙殖吸虫科的其余3个属的系统发育关系和确切系统位置仍不清楚，需要进一步研究，因为它们的分类主要基于生殖孔和阴茎囊的末端后位。根据我们的结果，副巴斯吸虫属似乎是并系的，需要进一步详细的系统发育和形态学分析。
