Daptonema williamsi sp.n. (Nematoda, Xyalidae) from the Solomon Islands

Daptonema williamsi sp.n. from the Ombo river, New Georgia, is described and figured in detail. The species shows some interesting morphological characters, mainly in the reproductive system, e.g. an hitherto undescribed protraction and rotation system of the spicules, matching a posteriorly directed vagina. D. williamsi closely resembles D. normandicum (de Man, 1890), D. oxycerca (de Man, 1888) and D. tenuispiculum (Ditlevsen, 1918). The first of these species has shorter spicules, longer setae on the male tail, only 3–4 ejaculatory glands and a vagina perpendicular to the body wall. D. oxycerca and D. tenuispiculum have differently shaped spicules. D. oxycerca has only 3–4 ejaculatory glands and in D. tenuispiculum the ovary does not extend to the level of the pharynx.