Revision of Severianoia (Schwenk, 1926) Travassos, 1929 (Nematoda: Oxyuridomorpha) with proposal of S. pachyiuli n. sp. from millipedes of the Western Caucasus

Abstract

Summary Severianoia pachyiuli n. sp. is described from the hind gut of Pachyiulus krivolutskyi (Diplopoda: Julidae) from the Republic of Adygea, Russian Federation. Females of the new species can be distinguished from those of S. magna by a smaller body and egg size; S. glomericola by smaller eggs and S. dubia by the organisation of the genital tract. Females of S. pachyiuli n. sp. are morphologically close to females of S. severianoi, but in described species males have significantly smaller body and spicule size. Severianoia pachyiuli n. sp. mostly resembles S. glomeridis by the general morphology in both sexes but differs in the position of the vulva, which is in a more posterior position to mid-body level in the described species. The description is supplemented with SEM and/or light microscope images of adults, juveniles and mature eggs. The phylogeny of the species is inferred from 18S and 28S rDNA. The taxonomic position of other representatives of Severianoia is discussed and Cephalobellus tipulae linstowi is regarded as a junior synonym of S. glomeridis.