The morphology and morphogenesis of a new Stichotrichida species, Heterodeviata longa nov. spec., isolated from a brackish water habitat in Qingdao, China, were investigated using live observation and the protargol staining method. The new species is morphologically distinguished by possessing one buccal, three to five parabuccal and three frontal cirri, one long frontoventral row of ca. 12 cirri extending beyond mid-body, four left and two right marginal cirral rows, and two dorsal kineties: (1) left dorsal kinety bipolar, comprising 16-23 dikinetids, and with one to three caudal cirri at its rear end, while (2) right dorsal kinety comprising only two dikinetids. During morphogenesis, four frontal-ventral cirral anlagen form both in the proter and the opisthe. The parental adoral zone of membranelles remains intact and is completely inherited by the proter. The anlagen for marginal rows and the left dorsal kinety develop intrakinetally. The right dorsal kinety is generated dorsomarginally. The 18S rRNA gene sequence of the new species has a similarity of 99.6 % and 98.1 % with two other congeners. Phylogenetic analysis supported their close relationship and the monophyly of the genus Heterodeviata.
