Octonchinae

Shi, Benze & Xu, Kuidong, 2016, Paroctonchus nanjiensis gen. nov., sp. nov. (Nematoda, Enoplida, Oncholaimidae) from intertidal sediments in the East China Sea, Zootaxa 4126 (1), pp. 97-106 : 99

Subfamily Octonchinae De Coninck, 1965

Emended diagnosis (based on the new description and Pastor de Ward et al. 2015). Oncholaimidae . Buccal cavity sclerotized, tapering posteriorly, with only posterior end surrounded by pharyngeal tissue. Buccal armature composed of three typical oncholaimid teeth with one of the ventrosublateral teeth the largest and many additional small teeth either distributed on the wall of buccal cavity or on mandibular ridges. Demanian system complex when present. Two reflexed ovaries and two opposed testes on right side of intestine. Tail conical or conical-cylindrical. Marine.

Remarks. The oncholaimid subfamily Octonchinae was established based on the morphology of a juvenile specimen of Octonchus marinus first described by Schulz (1932). Neither the true pattern of teeth nor the structure of reproductive system or of the demanian system is known ( Smol et al. 2014). Thus, Octonchus and its sole species O. marinus should be considered as a genus and species inquirenda.

Pastor de Ward et al. (2015) included the monotypic genus Patagonema in the subfamily Octonchinae and emended the diagnosis of Octonchinae by combining the two genera. Pastor de Ward et al. (2015) supposed Patagonema and Octonchus are homologous in origin simply based on a similar position of the mandibular teeth of Patagonema iubatum juveniles to those described by Schulz (1932). However, neither the three typical oncholaimid teeth nor the mandibular ridges could be recognized from the juvenile specimen of Octonchus marinus , whose taxonomic position is still pending.

In the present study, we describe a new species and genus, Paroctonchus nanjiensis gen. nov., sp. nov., which shows the typical oncholaimid teeth plus many additional small teeth. We assign Paroctonchus to the subfamily Octonchinae and provide an improved diagnosis for the subfamily, taking only the genera Paroctonchus and Patagonema into account.