Morphology of Cyclotrichium taniguchii sp. nov. and C. cyclokaryon with establishment of a new genus, Dicyclotrichium gen. nov. (Ciliophora: Haptorida)

Abstract

The morphology and infraciliature of two planktonic marine ciliates, Cyclotrichium cyclokaryon, type species of the genus and C. taniguchii sp. nov. were investigated on live and protargol-impregnated specimens collected from the Jiaozhou Bay at Qingdao, China. Based on the present as well as previous studies, an improved diagnosis for the poorly defined genus Cyclotrichium is suggested: Didiniidae with ovoid to barrel-shaped body; cell-surface densely ciliated except in the domed proboscis region; anterior ends of kineties with long cilia forming one circumoral wreath of pectinelles; one circumoral kinety composed of a zig-zag structure; dorsal brushes absent. Cyclotrichium taniguchii is distinguished from its congeners by the combination of the following features: ellipsoid body shape, marine habitat, details of ciliature, and lack of a posterior tuft. Based on the characters of the ciliary pattern, a new genus, Dicyclotrichium gen. nov., with the type species Dicyclotrichiumsphaericum comb. nov. is established. The new taxon differs from Cyclotrichium by having two wreaths of pectinelles. Two known morphotypes are suggested to be assigned into this genus: Dicyclotrichium faurei comb. nov. [basionym: Askenasia faurei] and D. humilis comb. nov. [basionym: Askenasia humilis].