The genus Psilotricha was established by Stein in 1859, with P. acuminata as the type species within the family Oxytrichidae. This species lacked a full description until it was re-discovered in 2001, showing that its morphological and morphogenetic characters confirmed the inclusion in the family Oxytrichidae. Since then, the genus Psilotricha has had a convoluted taxonomy despite the morphological evidence available. In this paper, we describe a new Psilotricha species, Psilotricha silvicola n. sp., from woodland soils in Southern England (United Kingdom). The morphology was investigated in live and protargol-impregnated specimens. Our findings show that P. silvicola n. sp. shares morphological characteristics with P. acuminata, including the distinctive cell shape and the long and sparse cirri. Phylogenetic analysis of the 18S rRNA gene places this new species within the family Oxytrichidae, nested apart from the family Psilotrichidae (which includes the genera Urospinula, Psilotrichides and Hemiholosticha), in a clade containing species of the family Oxytrichidae. Furthermore, the morphology of another Psilotricha species, P. viridis, found in a freshwater pond in the same woodland area, is also here described, bringing additional insight into the taxonomy of the genus. Our findings provide further evidence for inclusion of the genus Psilotricha within the oxytrichids.

Psilotricha属是由Stein在1859年建立的，其中P. acuminata是Oxytrichidae科中的典型物种。直到2001年被重新发现，该物种才有完整的描述，表明其形态学和形态发生学特征证实了该科已被列入该科。从那时起，尽管有可用的形态学证据，Psilotricha属仍具有复杂的分类学。在本文中，我们描述了一种新的Psilotricha种，Psilotricha silvicola n。sp。，来自英格兰南部（英国）的林地土壤。在活的和经异丙醇浸渍的标本中研究了形态。我们的研究结果表明，P。silvicola。sp。具有与P. acuminata相同的形态特征，包括独特的细胞形状和漫长而稀疏的卷毛。对18S rRNA基因进行系统进化分析，将这一新物种置于Ox虫科中，与P虫科（包括Urospinula，Psilotrichides和Hemiholosticha）分开嵌套，放进一个包含Ox虫科的进化枝中。此外，这里还描述了在同一林地的淡水池塘中发现的另一种P.silotricha菌的形态，即绿色假单胞菌，为该属的分类学带来了更多的见识。我们的发现为该属的纳入提供了进一步的证据。棘毛纲内的P.ilotricha。