Four freshwater cyrtophorids from the Lake Weishan Wetland, China (Protozoa, Ciliophora): taxonomy, phylogeny, and description of a new species

It has long been recognized that ciliates play a crucial role in microbial food webs in all kinds of biotopes. However, basic information about their species diversity, geographic distribution, and ecological function is scant, and molecular data are unavailable for most species. As a new contribution, a comprehensive survey of the diversity of ciliates in the Lake Weishan freshwater Wetland in northern China has recently been undertaken. In the present study, four species of the subclass Cyrtophoria were morphologically investigated including a new one, <i>Phascolodon paravorticella</i> sp. nov., which is characterized by having a body size 40–55 × 25–40 μm, 4 or 5 right and 4–7 left kineties, 20–22 nematodesmal rods, and two diagonally positioned contractile vacuoles. Three known forms, namely <i>Gastronauta aloisi</i>, <i>Trithigmostoma cucullulus</i>, and <i>Trithigmostoma steini</i>, are re-described based on the Lake Weishan Wetland populations. Additionally, phylogenetic analyses based on 18S rRNA gene sequences support the validity of the family Gastronautidae and imply that <i>Trithigmostoma cucullulus</i> contains cryptic species. The phylogenetic relationship between the families Chilodonellidae and Gastronautidae remains uncertain. http://zoobank.org/urn:lsid:zoobank.org:pub:6AF4F5E2-A7F1-4E32-A080-2B6B2435DC2A