Two Discocephalid Ciliates, Paradiscocephalus elongatus nov gen., nov spec. and Discocephalus ehrenbergi Dragesco, 1960, from the Yellow Sea, China (Ciliophora, Hypotrichida, Discocephalidae)

摘要

Two marine hypotrichs, Paradiscocephalus elongatus nov. gen., nov. spec. and Discocephalus ehrenhergi Dragesco, 1960, collected from the Yellow Sea, China, were investigated by living observation and protargol impregnation. The new genus differs from the known genera within the family Discocephalidae in the arrangement of its ventral cirri. The type species, P. elongatus nov. spec., can be identified by the following features: marine elongate elliptical body with cephalized anterior region; 110-180 mu m x 35-65 mu m in vivo; slightly flexible and fragile; six frontal cirri; on average seven pairs of ventral cirri arranged in an indistinct zig-zag pattern; nine to 11 well-developed transverse cirri; one row each of right, anterior left, and posterolateral marginal cirri; usually five to eight caudal cirri aligned in two rows located dorsolaterally; six or seven dorsal kinetics; numerous macronuclear nodules. An improved diagnosis of D. ehrenbergi is also given based oil a Chinese population and previous records. The small-subunit rRNA gene of P. elongatus was significantly different from that of Prodiscocephalus borrori (Wicklow 1982).