The genus Aridelus Marshall (Hymenoptera, Braconidae, Euphorinae) from Japan, with description of a new species Author Fujie, Shunpei https://orcid.org/0000-0002-1624-964X Osaka Museum of Natural History, Nagaikoen 1 - 23, Higashisumiyoshi, Osaka 546 - 0034, Japan shunpei.fujie@gmail.com Author Maeto, Kaoru Laboratory of Insect Biodiversity and Ecosystem Science, Graduate School of Agricultural Science, Kobe University, Rokkodaicho 1 - 1, Nada, Kobe, Hyogo 657 - 8501, Japan text ZooKeys 2022 2022-04-06 1092 105 122 http://dx.doi.org/10.3897/zookeys.1092.73299 journal article http://dx.doi.org/10.3897/zookeys.1092.73299 1313-2970-1092-105 85ACA852BA574845B15594B08C028559 CE6BAB58C80E54DB9F2DC4F1F5CC33C4 Genus Aridelus Marshall, 1887 Aridelus Marshall, 1887: 66; Papp 1965 : 181; Shenefelt 1969 : 11; Shaw 1985 : 309; Chou 1987 : 21; Chen and van Achterberg 1997 : 11; Belokobylskij 2000 : 362.Synonyms are presented in Shenefelt (1969) and Shaw (1985) . Type species (by monotypy). Aridelus bucephalus Marshall, 1887. Diagnosis. Head transverse; antenna filiform or moniliform, with 18 segments, its terminal segment with an apical spine; maxillary palp with 6 segments; labial palp with 4 segments; occipital carina complete or absent mediodorsally for a long distance, rarely completely absent, ventrally joining hypostomal carina; frons punctate or smooth with a median carina extending to frontal ocellus; face wider than clypeus in female; lower clypeal margin usually indented medially, rarely rounded; malar suture usually absent; mandibles overlapping each other; mesonotum, mesopleuron, and propodeum mostly areolate; petiolar notch extending nearly to mesocoxal insertions; parastigma large; vein 1-SR of fore wing absent to rarely shortly present and thickened; vein 3-SR of fore wing absent to distinctly present; vein 1-R1 of fore wing short; end of vein SR1 of fore wing much closer to pterostigma than to apex of wing; vein r-m of fore wing present; veins SR and 2-M of hind wing present, darkly pigmented; first metasomal tergite about 3/4 times as long as remainder of metasoma and completely fused ventrally; third tergite nearly reaching end of metasoma, following segments hidden; second and third tergites ventrally overlapping, without lateral fold; ovipositor and its sheath shortly exposed. Distribution. Cosmopolitan and the most diverse in tropical regions ( Yu et al. 2016 ). Bionomics. Endoparasitoids of nymphs and adults of Acanthosomatidae , Pentatomidae , Plataspidae , and Scutelleridae ( Shaw et al. 2001 ), and of Alydidae (present study). Usually diurnal, but a few species were collected at night in light traps (e.g., A. dubius in the present study).