Observations on the nematode genera Orientylus and Calvatylus (Rotylenchoidinae: Hoplolaimidae) with descriptions of three new species

Abstract

The genera Orientylus and Calvatylus are defined and differentiated. Four species are transferred from Rotylenchus to Orientylus and become O. helicus n.comb., and O. citri n.comb., O. secondus n.comb. and O. siddiqii n.comb. O. geraerti n.sp. from soil around grass roots at Dalhousie, District Chamba, H.P., India, is closely similar to O. orientalis but differs in the shape of the spear knobs which are 5 to 6 mm wide and backwardly sloping, in having a conspicuous hemizonid and hemizonion, a reduced posterior gonad in the female, and in being bisexual. O. varus n.sp., females only, was found in soil and roots of Pennisetum purpureum near Tembwe, Malawi. It differs from all other species of the genus in the shape of the female tail which is just over one anal body-width long, dorsally rounded, straight ventrally with 6 to 10 annules and a smooth, ventral subdigitate projection. The spear is smaller (20 to 23 mm) and the oesophageal gland lobe larger than in other species. One new species, Calvatylus heredicus n.sp., is described in the genus Calvatylus. It comes from apricot soil in Costa Rica, differs from C. calvus in body measurements (the female is 0.58 mm with a = 26, b = 6.1, c = 42, V = 61 and spear 24 mm) and in the shape of the female tail which has a distinct digitate projection (rounded in C. calvus).