The African Rhigonematoidea (Nematoda: Rhigonematida). 2. Six new species of Rhigonema Cobb, 1898 (Rhigonematidae)

Six new species of Rhigonema are described from the gut of various African diplopods. Rhigonema fecundum sp. n., from South Africa, is characterised by medium to fairly long body length, finely pilose anterior region, posterior margin of cephalic collar smoothly fused to body contour, Type 2 genital tract with a long ovejector, presence of a long, closely adpressed, vulval flap, tail shape in both sexes, broad spicules of medium length and complement of 23 copulatory papillae of which three pairs are subdorsal or sublateral in position. Rhigonema oxydesmi sp. n., from Oxydesmus platycercus concolor, Zaire, is characterised by medium body length, slightly projecting cephalic collar, finely pilose anterior region, Type 2 female genital tract with a long ovejector, presence of a short, adpressed, vulval flap, tail shape in both sexes, medium length spicules with a hamate capitulum and complement of 23 copulatory papillae, three pairs of which are subdorsal or sublateral in position. Rhigonema peziphorum sp. n., from Sphaerotherium selindum, Zimbabwe, is characterised by medium body length, prominently projecting cephalic collar, finely pilose anterior region, Type 1 female genital tract with a medium length ovejector, rather large eggs, absence of a prominent vulval flap, presence of a spermatophore, tail shape in both sexes, unusually short spicules with a weakly hamate capitulum and complement of 23 copulatory papillae. It is the only known Rhigonema species to form a spermatophore. Rhigonema rostrellum sp. n., from Ivory Coast, is characterised by medium body length, finely pilose anterior region, Type 2 genital tract with a very long ovejector, presence of a closely adpressed vulval flap, tail shape in both sexes, broad spicules of medium length and complement of 23 copulatory papillae of which three pairs are subdorsal or sublateral in position. Rhigonema spicatum sp. n., from Congoromus flabellatus, Zaire, is characterised by medium body length, slightly projecting cephalic collar, densely pilose anterior region, Type 2 female genital tract with a long ovejector, presence of an adpressed vulval flap, tail shape in both sexes, relatively short spicules with a hamate capitulum and complement of 23 copulatory papillae. Rhigonema xiphiurus sp. n., from Oxydesmus sicarius, Zaire, is characterised by medium body length, projecting cephalic collar, coarsely pilose anterior region with bristly microtrichs, microtrichs extending down body to beyond vulval level in female and a similar relative position in the male, Type 2 female genital tract with a long ovejector, elongate female tail, convex conoid male tail with an exceptionally well developed subulate projection, very short spicules and disposition of the 23 copulatory papillae, three pairs of which are dorsal or sublateral in position. A synopsis of the other eight nominal species of African Rhigonema is appended.