Protomicroplitis Ashmead, 1898: 167. Original description. No species included, no type species designation.
Protomicroplitis germani Ashmead 1900 b: 132. Nomen nudum. Invalid designation of type species. Incorrect original spelling of species name.
Protomicroplitis mediatus (Cresson, 1865). Ashmead, 1900 a: 292. Species included, no designation of type species.
Protomicroplitis mediatus (Cresson, 1865). Viereck 1914: 124. Designation of type species (by monotypy).
Microgaster Latreille, 1804. Muesebeck 1922: 20. Status revised (synonymized under Microgaster).
Protomicroplitis Ashmead, 1898. Nixon, 1965: 234. Status revised (genus resurrected).
Protomicroplitis Ashmead, 1898. Mason, 1981: 124. Status revised (generic limits revised).
Description. Head relatively transverse (maximum width of head 1.35–1.45 × its height) (Figs 8, 12, 20, 25); antenna with placodes comparatively short (0.2–0.4 × as long as a flagellomere) and scattered irregularly along the length of the flagellomere (so that the appearance of a middle constriction in the flagellomere, typical in most Microgastrinae, is missing); apical flagellomeres relatively elongated, length of flagellomere 2 at most 1.9 × length of flagellomere 14; anteromesoscutum smooth to finely punctate (punctures shallow and sparse), with little or no trace of notauli (Figs 4, 15, 23, 29); apical polished rim of scutellar disc interrupted medially by sculpture (Figs 9, 15); propodeum strongly rugose and with median carina (Figs 9, 16, 24, 29); fore wing with triangular areolet (Figs 6, 13, 19, 28); hind wing with vannal lobe strongly convex, margin with very short setae; T 1 rather strongly constrained medially (width at half length of tergite 0.4–0.6 × its width at anterior and/or posterior margins of tergite) (Figs 7, 17, 22); T 1 length around 4.0 × its width at apex, and at least 6.0 × its width at half length of tergite; hypopygium short and not pleated medially (Figs 10, 14); ovipositor short, decurved and abruptly tapered near the middle (Fig. 10); relatively large body length (4.4–5.5 mm, usually over 4.8 mm), and fore wing length (4.1–5.2 mm, usually over 4.4 mm); body length usually (but not always) 0.1–0.2 mm larger than fore wing length.
The relatively large but thin mediotergite 1, which is distinctively narrower medially, is a diagnostic feature of Protomicroplitis. Only the genus Wilkinsonellus and a few species of Diolcogaster (mostly D. lelaps and morphologically related species, all forming what has been called the lelaps species-group –e.g., Nixon 1965) have similar mediotergite 1. Wilkinsonellus has no areolet in the fore wing, and a very distinctive and unique venation pattern. The Diolcogaster lelaps species-group has a quadrangular areolet which is relatively larger than that of Protomicroplitis species (which have a relatively small and triangular areolet). Additionally, the antenna in Protomicroplitis has short and irregular placodes whereas both Wilkinsonellus and the D. lelaps species-group have placodes arranged in two ranks, with the median constriction characteristic of most Microgastrinae.