A neotype for Cephalobus persegnis Bastian, 1865, redescription of the species, and observations on variability in taxonomic characters

Abstract

Amendment of the description of males and females of Cephalobus persegnis includes variation in the form of the probolae, reproductive system, and tail, and in the number and position of the lateral papillae on the male tail. Size and shape of the dorsal and subventral rectal glands also differed within and between sexes. Form of the probolae of topotypes and their progeny reared on agar and in sand ranged from low-rounded, when amalgamated with the duplex lips, to asymmetrically bifurcate. Sometimes probolae became conoid in shape, ending in a single point. Significance of the presence or absence and the form of labial probolae in taxonomy of Cephalobus and in its relationships to the Acrobelinae, particularly Chiloplacus Thorne, 1937 and Paracephalobus Akhtar, 1962, is discussed. Chiloplacus trilineatus Steiner, 1940 is synonymized with C. persegnis. Chiloplacus quinilineatus Shavrov, 1968 is transferred to Cephalobus. Configuration of the ovary in adult females is not considered to be of taxonomic significance. The ovary is not always flexed, and, when flexed, the number of flexures varies from one to six. The neotype of C. persegnis was selected from specimens collected from the type locality.