Canadian species of the genus Helicotylenchus Steiner, 1945 (Nematoda: Hoplolaimidae), their identifying characteristics and descriptions of three new species

Abstract

Descriptions, illustrations, distribution, and host affiliations are presented for 12 species of spiral nematodes that occur in Canada, including 3 new species. The only bisexual species, H. cornurus n. sp., is distinguishable from closely related species with a rounded head and ventral tail projection by the development of the head skeleton, length of the spear, width of the lateral field, spicula dimensions, and annulation of the tail terminus, which typically is indented. A prominent labial disc in H. phalerus n. sp. is one of the more important characters that distinguishes it from closer relatives. H. teleductus n. sp. is unique in the posterior position of the dorsal gland duct terminus (14 to 17 μ from the spear knobs) and of the excretory pore, which is well posterior to the esophagointestinal valve. Ranges in dimensions and form within the remaining Canadian species complement other descriptions and provide new information of diagnostic value. A key is presented to facilitate separation of the Canadian species.