A supplemental key to species of Helicotylenchus Steiner, 1945 (Nematoda: Hoplolaimidae) described since 1972 and a description of H. oscephalus n.sp.

Abstract

A parthenogenetic spiral nematode, Helicotylenchus oscephalus n.sp., collected from high elevations is described and illustrated. Its distinguishing characters are a hemispherical head with six to eight annules, a strongly sclerotized head skeleton with a deeply depressed septum, a sty let 25 to 28 μm long, hemizonid three to six annules anterior to the excretory pore, and a conoid, broadly rounded tail that is longer than the anal body width. A key is provided for 50 species of Helicotylenchus not included in existing keys.