Abstract
The morphology, morphogenesis, and SSU rDNA sequence of a Caudiholosticha stueberi population from Southwest China soil were analyzed. The studies confirm the assumption of previous workers that this species has dorsomarginal kineties and thus does not belong to the urostyloids, but to the non-oxytrichid dorsomarginalian genus Uroleptus whose members have, in contrast to C. stueberi, a distinct tail. On the basis of two morphological features we split Uroleptus into three subgenera: U. (Uroleptus) (tail present; more than five transverse cirri; habitat freshwater), U. (Paruroleptus) (present; five or less; freshwater or soil), and U. (Caudiholosticha) stat. nov. (lacking; five or less; soil). Since Uroleptus (Caudiholosticha) stueberi comb. nov. is the type of Caudiholosticha, the other 16 species so far assigned to Caudiholosticha have to be reclassified because they obviously lack dorsomarginal kineties. Based on published data, six new urostyloid genera are established: Extraholosticha gen. nov. (type: Holosticha sylvatica; monotypic); Adumbratosticha gen. nov. (type: H. tetracirrata; three species); Acuholosticha gen. nov. (type: U. paranotabilis; five species); Limnoholosticha gen. nov. (type: H. (Holosticha) navicularum; four species); Multiholosticha gen. nov. (type: H. multicaudicirrus; two species); and Caudikeronopsis gen. nov. (type: Caudiholosticha marina; monotypic). Urosomoida sejongensis is transferred to Oxytrichella: O. sejongensis comb. nov.