Genus Diolcogaster Ashmead, 1900

Diolcogaster Ashmead, 1900: 132 (description). Mason, 1981: 113 (redescription). Type species: Microgaster brevicaudus Provancher, 1886: 140, by monotypy, Lectotype ♀ — Québec, Canada [ECLU, Provancher’s collection, no. 1167, Figs 16 F–16G].

Zadiolcogaster Viereck, 1913: 366 (description). Type species: Zadiolcogaster anomus Viereck, 1913: 366 . Holotype ♀ — Asuncion, Paraguay [ZMHB, Figs 2 A–2F].

Diagnosis. Pronotum rarely with dorsal sulcus (Figs 2C, 4A, 6A, 8A, 10A, 12A, 14A); when an areola is absent, propodeum with medio-longitudinal carina strong and complete, usually rugose but occasionally smooth (Figs 2 E–2F, 4B, 6B, 8B, 10B, 12B, 14B); fore wing with areolet in variable sizes, sometimes areolet small or poorly delimited posteriorly, veins 3RSa and/or r-m might be unpigmented but still visible (Figs 2B, 4F, 6 F–6G, 8F, 10F, 12F, 14F); metacoxa large, extending to or beyond end of T3 (Figs 2A, 3A, 3C, 4E, 5A, 7A, 8E, 9A, 10E, 11A, 12E, 13A, 14E); inner metatibial spur always longer than outer spur, its length varying from half-length of basitarsus to longer than hind basitarsi (Figs 2 A–2B, 3C, 5C, 7C, 9C, 11C, 13C); T1 anteriorly with a sharp medio- longitudinal sulcus through most of its length, varying from absent, shallow and small, short and expanded apically to strongly narrowed, strap-shaped (Figs 2 E–2F, 4C, 6C, 7C, 10C, 12C, 14C); T2 usually with a triangular median field, which can be varies on different asymmetric shapes, sometimes without median field (Figs 4 C–4D), T3 smooth, but strongly rugose when the second one is similarly sculptured (Figs 2 E–2F, 4C–4D, 6C–6D, 8C, 10C–10D, 12C–12D, 14C–14D); ovipositor and ovipositor sheaths short and barely exerted, ovipositor sheaths usually with dense setae near apex and in most species with a few modified strong setae (Figs 2A, 4E, 6E, 8E, 112E, 14E).

Global distribution. Cosmopolitan, but more diverse in tropics.

The number of species. Diolcogaster is with 101 described valid species currently the seventh largest genus of Microgastrinae (Yu et al. 2016; Fernandez-Triana 2018; Salgado-Neto et al. 2018).

Hosts. Solitary or gregarious koinobiont endoparasitoids of various macrolepidoptera.

* The included ratios for D. alvearia obtained from examined specimens from Israel.