Morphogenesis of the marine ciliate Pseudokeronopsis flava (Cohn, 1866) Wirnsberger et al., 1987 (Protozoa: Ciliophora: Hypotrichida)

摘要

Morphogenetic events during the binary division of the little-known marine hypotrichous ciliate, Pseudokeronopsis flava (Cohn, 1866) Wirnsberger, Larsen & Uhlig, 1987, collected from the littoral area of Zhanjiang, South China are described based on protargol-impregnated specimens. The basic process in the Zhanjiang population corresponds well with other congeners and presents the following characteristics: 1) in the proter, the oral primordium and undulating membranes-anlage generate de novo under the surface of the buccal cavity, and hence clearly separated from the fronto-ventral-transverse-cirral anlagen in the proter；2) the old adoral zone of membranelles in the proter is completely replaced by newly-built structures；3) the fronto-ventral-transverse-cirral anlagen in both the proter and opisthe originate apokinetally；4) the oral primordium, undulating membranes-anlagen and the fronto-ventral-transverse-cirral anlagen in the opisthe develop from the same anarchic field of basal bodies；5) marginal cirral rows and dorsal kineties develop in a usual way, of which the anlagen appear within the parental structures and stretch toward both sides to replace the old structures；6) in the process of morphogenesis, macronucleus segments divide without prior fusing. The phylogenetic significance of these morphogenetic events are discussed. Compared with other taxa in spirotrichs, the phenomenon of the subcortical origin of the oral primordium in the proter of the present species is, in the authors’ opinion, possibly a convergent feature [ Acta Zoologica Sinica 51(1):81 - 88, 2005].