Morphology and morphogenesis of the poorly-known marine urostylid ciliate, Metaurostylopsis marina(Kahl, 1932) nov. gen., nov. comb. (Protozoa, Ciliophora, Hypotrichida)

Abstract

The morphology and morphogenesis of the hypotrichous ciliate, Metaurostylopsis marina (Kahl, 1932) nov. gen., nov. comb. (basionym: Urostyla marina Kahl, 1932), found in coastal waters off Qingdao (Tsingtao), China, are described using live observations and protargol silver impregnation. The new genus Metaurostylopsis is characterized thus: Urostylidae with frontoterminal cirral row and several clearly differentiated enlarged frontal cirri; buccal and transverse cirri present, caudal cirri absent; more than one row of marginal cirri on each side which derive from individual anlagen within each parental row; oral primordium for proter probably developing from a “pocket” beneath pellicle of buccal cavity. The improved diagnosis for Metaurostylopsis marina (Kahl, 1932) nov. comb. is: in vivo 80—120 × 50—80 μm, oval to elongate ellipsoid, conspicuous cortical granules in rows along dorsal kineties and anterior body margin; 3—5 marginal cirral rows on each side of the cell; 27—30 adoral membranelles, 3—4 slightly enlarged frontal, 3—6 frontoterminal, 1 buccal and 5—9 transverse cirri; 7—11 midventral cirral pairs; usually with 3 (3—4) complete dorsal kineties; about 50 macronuclear nodules and about 5—10 micronuclei. The main features of divisional morphogenesis are: 1) the entire parental ciliature including the oral apparatus is renewed; 2) the oral primordium of the proter originates de novo and probably within a pouch beneath the parental buccal cavity; 3) each parental marginal cirral row develops 2 separate anlagen intrakinetally; 4) each parental dorsal kinety forms 2 separate anlagen each intrakinetally; 5) the macronuclear segments do not form the usual rounded mass, but rather a unique, branched complex.