Some studies on Tylenchorhynchinae: proposal of Divittus n.g. (Nematoda: Tylenchida)

Abstract

A new genus Divittus is proposed in the subfamily Tylenchorhynchinae Eliava, 1964 with only three incisures in the non-areolated lateral fields and the body cuticle without longitudinal ridges or lamellae. It is also proposed to restrict Trilineellus Lewis & Golden, 1981 to its type species only, i.e.,T. clathrocutis which has three incisures in the lateral fields and longitudinal ridges or lamellae on the body, and Tylenchorhynchus to species which have four incisures in the lateral fields but no ridges or lammellae.T. divittatus Siddiqi, 1961, T. triglyphus Seinhorst, 1963 and T. sculptus Seinhorst, 1963 which were transferred toTrilineellus by Lewis & Golden (1981) are now included in Divittus with the following species of Tylenchorhynchus which have three incisures in the lateral fields: T. obscurisulcatus Andrassy, 1959,T. chonai Sethi & Swarup, 1968,T. madrasensis Gupta & Uma, 1981 and T. pruni Gupta & Uma, 1981. The synonymy of T. chonai with T. triglyphus proposed by Tarjan (1973) is not accepted. Divittus labiatus n.sp. from soil around roots of sugarcane from north-eastern Nigeria is described. It is characterized by having the lip region continuous with the body, the spear 14-16 µ m long, the basal oesophageal bulb with a small overlap over the intestine and the tail with a large post-anal intestinal sac and 20 to 30 annules. A key to species of Divittus is provided.