Redescription and phylogeny of the little-known type species Rhinakis faurei Deroux, 1994 (Alveolata, Ciliophora, Nassophorea)

Ciliates of the class Nassophorea Small & Lynn, 1981, inhabit a wide range of aquatic environments and serve as a trophic link in microbial food webs. However, their diversity remains underestimated. In the present study, the morphology and molecular phylogeny of <i>Rhinakis faurei</i> Deroux, 1994, an insufficiently known nassulid ciliate, were investigated using an integrative taxonomic approach. The studied population was collected from a freshwater pond in Qingdao, China. Details of the live morphology and ciliature of <i>R. faurei</i> are documented for the first time, and an improved species diagnosis is provided. Phylogenetic analyses of the small subunit ribosomal RNA gene sequence revealed that <i>R. faurei</i> clusters within the family Nassulidae de Fromentel, 1874. However, evolutionary interrelationships within the Nassulidae remain obscure owing to under-sampling, the lack of sequence data for most nominal species, and low nodal support or unstable gene tree topologies.