Description of Metarhabditis giennensis sp. n. (Nematoda, Rhabditida, Rhabditidae) from decaying wood of a riverbank forest in the southern Iberian Peninsula.

A new species of the genus Metarhabditis, M. giennensis sp. n., collected from a riverbank poplar forest in the southern Iberian Peninsula, is described and illustrated, including SEM observations. The new species is characterized by its 1.01-1.16 mm long body in females and 0.77-0.98 in males, cuticle with very fine transverse striation, lip region 9-14 µm broad and consisting of six swollen rounded lips fused in pairs, stoma 14-25 µm long with tubular gymno-promesostegostom, pharynx with slightly swollen metacorpus and slender isthmus, nerve ring, excretory pore and deirids located at isthmus level, female reproductive system didelphic-amphidelphic, vulva equatorial (V = 49-50), female rectum length 1.2-1.7 times the anal body width, female tail conical-elongate with acute tip (123-199 µm, c = 5.8-8.2, c' = 8.2-11.1), male tail conical (34-56 µm, c = 15.5-25.7, c' = 2.4-3.5), bursa leptoderan, 32-41 µm long spicules with rounded and ventrally bent manubrium, and 17-20 µm long gubernaculum. An updated list of species of the genus and a key for their identification are also provided. [Zoobank URL: urn:lsid:zoobank.org:act:7EBAC9DB-A148-4A1A-97E5-3B796D0839BF].