A taxonomic review and revisions of Microstomidae (Platyhelminthes: Macrostomorpha)

Microstomidae (Platyhelminthes: Macrostomorpha) diversity has been almost entirely ignored within recent years, likely due to inconsistent and often old taxonomic literature and a general rarity of sexually mature collected specimens. Herein, we reconstruct the phylogenetic relationships of the group using both previously published and new 18S and CO1 gene sequences. We present some taxonomic revisions of Microstomidae and further describe 8 new species of Microstomum based on both molecular and morphological evidence. Finally, we briefly review the morphological taxonomy of each species and provide a key to aid in future research and identification that is not dependent on reproductive morphology. Our goal is to clarify the taxonomy and facilitate future research into an otherwise very understudied group of tiny (but important) flatworms.

微口涡虫科（Microstomidae，扁形动物门：大口涡虫类Macrostomorpha）的物种多样性在近年几乎完全被忽视，这一状况大概率源于其分类学文献杂乱且年代久远，同时性成熟标本的采集普遍较为稀缺。本研究整合已发表及新获取的18S与CO1基因序列，重建了该类群的系统发育关系。我们对微口涡虫科开展了部分分类学修订，并结合分子与形态学证据，正式描述了8个微口涡虫属（Microstomum）新物种。最后，我们简要梳理了各物种的形态分类学特征，并提供了无需依赖生殖形态即可辅助未来研究与物种鉴定的检索表。本研究旨在厘清该类群的分类学现状，以推动对这一长期被严重忽视的小型（却具有重要生态学意义）扁形动物类群的后续研究。