Redescription of Neocephalobus aberrans Steiner, 1929 (Rhabditida, Panagrolaimidae) with restoration of the genus and its taxonomic implications

Summary Two populations of slug-associated nematodes were isolated in different habitats, including agricultural fields and mango gardens in the Baghpat district of Western Uttar Pradesh, India. Initial morphological characterisation shows that they resemble the nematodes of the family Panagrolaimidae. Morphological and morphometrical characterisation confirm this and show that both populations belong to the species described initially as Cephalobus ( Neocephalobus ) aberrans (later as Neocephalobus aberrans , currently as Panagrolaimus aberrans , and here reinstated as Neocephalobus aberrans ). Using morphological and molecular data, we found that this species does not belong to the genus Panagrolaimus . Hence, the last taxonomic proposal of transferring it from the genus Neocephalobus to the genus Panagrolaimus should be reversed, and therefore, the genus Neocephalobus is reinstated as a valid genus, and Neocephalobus aberrans a valid species. In addition, we observed that the species described initially as Evaginorhabditis agaricus (currently as Panagrolaimus agaricus ) is morphologically identical to C . ( N .) aberrans , and therefore, should be considered its junior synonym, and the genus Evaginorhabditis a junior synonym of Neocephalobus . In addition, we observed that the species of the Neocephalobus are morphologically very similar to those of the genus Tricephalobus . Accordingly, we propose the genus Tricephalobus as a junior synonym of Neocephalobus . Thereby species included in the genus Tricephalobus are transferred to the genus Neocephalobus as N. aestivus n. comb., N. lignicola n. comb. and N. steineri n. comb.