Genus Diplopeltoides Gerlach, 1962 Type species Diplopeltoides ornatus (Gerlach, 1950). Diagnosis (emended after Holovachov 2014) Cuticle annulated, annulation starts at level with the amphids; annules smooth or with fine longitudinal striation. Annules unequal in width; annule width increases gradually from first postcephalic annule to annule located somewhat posterior to the pharyngo- intestinal junction, which is followed by a much narrower one; annules increase in width posterior towards mid-body region. Posterior to two-thirds of body length, annule width gradually decreases again, with the most narrow annule located on tail; the most narrow caudal annule is followed posteriorly by one much wider annule and then by caudal annules, in which the width gradually decreases toward the tail terminus. Lateral alae absent. Body pores and epidermal glands absent. Somatic sensilla present. Labial region bluntly rounded; lip pairs fused into three small lobes. Inner labial sensilla invisible if present. Outer labial sensilla pore-like, located on the anterior surface of lips. Cephalic sensilla setiform or papilliform; their bases located at the base of the labial region, anterior to amphid. Subcephalic and cervical sensilla, deirid and ocelli absent. Amphids in some species lie on strongly cuticularised lateral subcuticular plates that are partly or completely connected together on the ventral and dorsal sides forming a “cephalic framework”. Amphidial fovea loop-shaped (inverted U-shaped). Secretory-excretory system usually present; renette cell elongate, located opposite to the cardia and anterior part of intestine. Secretory-excretory ampulla present, located at the level of the posterior part of pharynx. Cuticularized secretory-excretory duct very short, opens to the exterior posterior to the nerve ring level. Buccal cavity small funnel-shaped: cheilostom can usually be seen as the cylindrical or funnel-shaped anterior-most part, not cuticularised; gymnostom short and not cuticularised; stegostom closed, linear, its slender lining continuous with that of the corpus. Pharyngeal tubes absent. Pharynx subdivided by breaks in muscular tissue into anterior corpus and posterior postcorpus; corpus cylindrical or fusiform, muscular, with evenly distributed myofilaments; postcorpus glandular, consisting of anterior narrower isthmus and basal swelling; dorsal sector of the basal bulb is often enlarged to accommodate dorsal pharyngeal gland; pharyngeal lumen uniform in thickness along the entire pharynx length; valves absent. Dorsal and two subventral gland orifices penetrate pharyngeal lumen at the base of stoma. Dorsal gland nucleus is visible in the basal swelling. Cardia conoid, glandular. Female reproductive system didelphic-amphidelphic with equally developed branches, ovaries reflexed antidromously. Spermatheca absent. Vulva equatorial, transverse or pore-like. Vagina straight; pars proximalis vaginae encircled by sphincter muscle; pars refringens vaginae and epiptygmata absent. Male reproductive system diorchic, testes outstretched or opposed in different species. Spicules symmetrical, arcuate; gubernaculum usually present. Supplements, precloacal and postcloacal sensilla absent. Setae in caudal region of males arranged in subventral and subdorsal pairs along the tail. Three caudal glands present, open via three separate openings, their nuclei are incaudal. Spinneret absent. Valid species Diplopeltoides anatolii (Voronov, 1982) = Diplopeltula anatolii Voronov, 1982 Diplopeltoides asetosus (Juario, 1974) comb. nov. = Diplopeltula asetosa Juario, 1974 Diplopeltoides axayacatli Holovachov, Tandingan De Ley, Mundo-Ocampo, Gingold & De Ley, 2009 Diplopeltoides botulus (Wieser, 1959) comb. nov. = Diplopeltula botula Wieser, 1959 Diplopeltoides bulbosus (Vitiello, 1972) comb. nov. = Diplopeltula bulbosa Vitiello, 1972 Diplopeltoides grandis sp. nov. Diplopeltoides linkei Jensen, 1991 Diplopeltoides longicaudatus sp. nov. Diplopeltoides lucanicus (Boucher & Helléouët, 1977) comb. nov. = Diplopeltula lucanica Boucher & Helléouët, 1977 Diplopeltoides mastigia Tchesunov, 1990 Diplopeltoides nudus (Gerlach, 1956) = Diplopeltula nuda Gerlach, 1956 Diplopeltoides ornatus (Gerlach, 1950) = Diplopeltis ornatus Gerlach, 1950 Diplopeltoides paramastigia Holovachov, Tandingan De Ley, Mundo-Ocampo, Gingold & De Ley, 2009 Diplopeltoides pulcher (Vincx & Gourbault, 1992) = Diplopeltula pulchra Vincx & Gourbault, 1992 Diplopeltoides pumilus (Vincx & Gourbault, 1992) comb. nov. = Diplopeltula pumila Vincx & Gourbault, 1992 = Diplopeltoides holovachovi Fadeeva & Mordukhovich, 2013 syn. nov. Diplopeltoides santaclarae Holovachov, Tandingan De Ley, Mundo-Ocampo, Gingold & De Ley, 2009 Diplopeltoides striatus (Gerlach, 1956) comb. nov. = Diplopeltula striata Gerlach, 1956 Diplopeltoides suecicus sp. nov. Diplopeltoides sundensis (Jensen, 1978) = Diplopeltula sundensis Jensen, 1978 Nomenclatorial changes 1) Diplopeltula asetosa Juario, 1974 is here transferred to the genus Diplopeltoides based on the morphology of the female reproductive system with reflexed ovaries in this species vs outstretched ovaries as defined for the genus Diplopeltula by Fonseca & Bezerra (2014) and Leduc (2017). 2) Diplopeltula botula Wieser, 1959 is here transferred to the genus Diplopeltoides based on the fact that it shows no qualitative differences from several species currently assigned to the genus Diplopeltoides. 3) Diplopeltula bulbosa Vitiello, 1972 is here transferred to the genus Diplopeltoides based on the morphology of the female reproductive system with reflexed ovaries in this species vs outstretched ovaries as defined for the genus Diplopeltula by Fonseca & Bezerra (2014) and Leduc (2017). 4) Diplopeltula lucanica Boucher & Helléouët, 1977 is here transferred to the genus Diplopeltoides based on the characteristic morphology of the amphid (with a crenate interamphideal shield – a feature common to other species of Diplopeltoides, but not in Diplopeltula and its type species Diplopeltula breviceps Gerlach, 1950). 5) Diplopeltula pumila Vincx & Gourbault, 1992 is here transferred to the genus Diplopeltoides based on its close morphological affinities to Diplopeltoides holovachovi Fadeeva & Mordukhovich, 2013 in general morphology, structure of cuticle, anterior end and spicules. Since the only known difference between the two species is in the length of the spicules, Diplopeltoides holovachovi is here considered a junior synonym of Diplopeltoides pumilus. 6) Diplopeltula striata Gerlach, 1956 is here transferred to the genus Diplopeltoides based on unpublished observations on the morphology of the female reproductive system (reflexed ovaries) in this species.

Published as part of Holovachov, Oleksandr & Boström, Sven, 2017, Three new and five known species of Diplopeltoides Gerlach, 1962 (Nematoda, Diplopeltoididae) from Sweden, and a revision of the genus, pp. 1-35 in European Journal of Taxonomy 369 on pages 3-5, DOI: 10.5852/ejt.2017.369, http://zenodo.org/record/3838436