The morphology, morphogenesis and small subunit rRNA (SSrRNA) gene sequence of a new marine euplotid ciliate, Diophrys apoligothrix spec. nov., isolated from a sandy beach near Qingdao, north China, were investigated. This organism is characterized as follows: rigid body with a sculptured surface; size in vivo about 60-110 x 40-70microm; adoral zone comprising about 28 membranelles; five frontal, two ventral, five transverse, one left marginal and three caudal cirri; five dorsal kineties with sparsely distributed dikinetids; two ellipsoid macronuclear nodules; marine habitat. Although the main morphogenetic events are similar to those reported in other congeners, three features are noteworthy: (1) the parental adoral zone is retained almost unchanged by the proter except for the outer margin of membranelles in the proximal portion, where the de-differentiation and then reorganization take place in situ in the mid-to-late phases of division; (2) the dorsal kinety anlagen are formed via a two-step mode; (3) the marginal cirrus anlage is formed de novo near the old structure and does not divide. Based on the morphological, morphogenetic and SSrRNA gene sequence data, it was concluded that D. apoligothrix is a well-outlined and distinctive member of the genus Diophrys.