Morphology and Molecular Phylogeny of Two Marine Folliculinid Ciliates Found in China (Ciliophora, Heterotrichea)

Ciliates of the heterotrich family Folliculinidae are characterized by their transparent lorica, conspicuous peristomial lobes pair and dimorphic life cycle, a sessile trophont and a motile swarmer. However, understanding their biodiversity and systematics is relatively poor. In the present study, two species representing two genera of folliculinids, which were collected from marine and brackish habitats in China, were investigated with morphological and molecular methods. The genus Diafolliculina n. gen. is established for D. longilobata n. sp. Detailed morphological redescriptions for another species Eufolliculina is provided. Moreover, phylogenetic analysis based on small subunit ribosomal DNA (SSU rDNA) sequences showed that 1) all two genera locate in the Folliculinidae clade; 2) Metafolliculina clusters with Eufolliculina; and 3) two genera (Diafolliculina and Ampullofolliculina) with a lorica closure device have close affinities with Folliculina. The lorica of Diafolliculina and Ampullofolliculina lacks a closure device, thereby the phylogeney contradicts the morphology-based classification.