Setonophrys tricorniculata Clamp 1991

Loricate peritrich ciliate, lorica hemispherical, subcircular, or suboval in dorsal view. Lorica rim heavily thickened. Posterior and lateral portions of lorica rim uniformly thick. Segments of rim directly laterad of lorica aperture slightly wider than posterior and lateral parts of rim; segment of rim directly anteriad of aperture much wider than posterior and lateral portions. Wider segments of rim project inward rather than outward, preserving regular outline of margin of lorica in dorsal view. Lips of lorica aperture tall, symmetrical in shape, located close to anterior margin of lorica. Anterior lip of aperture moderately arched, with three long and thick spines that project from the edge at the following points: near left end of lip; slightly to left of center of lip, and near right end of lip. Spine near left end of anterior lip more or less straight, projecting almost directly laterad, with tip occasionally flexed to form a hook. Spine slightly to left of center of anterior lip with proximal one-third projecting antedad; distal two-thirds of spine bending sharply toward left at approximately right angle to proximal one-third. Spine near right end of anterior lip with proximal half projecting antedad or nearly so, distal half of spine bends sharply toward right at approximately right angle to proximal half. Posterior lip of aperture pulled completely inside lorica and pressed against anterior lip to effect closure of aperture; posterior lip loses its shape on closing. Macronucleus elongate, located in approximate center of body. Middle portion of macronucleus extremely slender, straight or slightly curved, parallel to transverse axis of body or slanting posteriad from left to right at slight angle to transverse axis; ends of macronucleus much thicker than medial portion, curved anteriad away from medial portion. Micronucleus ovoid, always located near right end of macronucleus.