Morphology, Morphogenesis and Molecular Phylogeny of Two Freshwater Ciliates (Alveolata, Ciliophora), with Description of sp. nov. and Redefinition of and .

Ciliated microeukaryotes are insufficiently investigated despite their ubiquity and ecological significance. The morphology and morphogenesis of a new Stichotrichida species, sp. nov., and the known Foissner et al., 2002, are here studied using live observations and protargol staining methods. The new species is characterized by having one buccal, one parabuccal and three frontal cirri, one frontoventral row extending to the posterior half of the cell, three left and two right marginal rows and three dorsal kineties with the left kinety conspicuously bipartite, along with one caudal cirrus at the rear end of each kinety. During morphogenesis, there exist five frontal-ventral cirral anlagen with anlagen IV and V forming a frontoventral row in the proter, and four cirral anlagen with only anlage IV generating a frontoventral row in the opisthe. The anlagen for marginal rows and dorsal kineties develop intrakinetally. The new population of corresponds well with other isolates regarding morphology and cell development. Phylogenetic analyses based on small subunit ribosomal gene sequence data revealed that both and are deeply clustered in the clade consisting of species from the genera and , supporting the placement of both genera into the family Deviatidae Foissner, 2016.