Deladenus nitobei n. sp. (Tylenchomorpha: Allantonematidae) isolated from Sirex nitobei (Hymenoptera: Siricidae) from Aomori, Japan, a new member of the siricidicola superspecies

Deladenus nitobei n. sp., a parasite of a woodwasp species, Sirex nitobei , is described based on its typological characters and molecular profiles of part of the small subunit D2-D3 expansion segments of the large subunit and internal transcribed spacer region of the ribosomal RNA gene, as well as part of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene. Adult host woodwasps emerging from dead Japanese red pine logs, Pinus densiflora , collected at Aomori, Japan, were dissected and examined for nematode association. The new species was isolated from the body cavity and reproductive system of S. nitobei as large parasitic females and small parasitic juveniles. The nematodes were cultured successfully on 1.0% malt extract agar medium, inoculated with Sirex -associated fungus, Amylostereum areolatum . The mycophagous adult nematodes were characterised by the relative position of the excretory pore, located at 25 (19-28) and 25 (18-30) μ m anterior to the hemizonid in the male and female, respectively, and a broad female tail with a rounded distal end. Typologically, the new species forms a cryptic species complex with D. siricidicola and D. canii . In addition, the new species and D. siricidicola share the same host wasp, tree and fungal species in Japan. However, the cryptic species can be separated from each other based on the described morphological and molecular sequence differences in the mtCOI gene.