Ismaridae Thomson, 1858

Chemyreva, Vasilisa G., Perkovsky, Evgeny E. & Vasilenko, Dmitry V., 2024, First record of the parasitoid family Ismaridae (Hymenoptera, Diaprioidea) from Eocene Baltic and Rovno ambers with the description of a new genus and two new species, Zootaxa 5418 (4), pp. 328-338 : 329

Family Ismaridae Thomson, 1858

Diagnosis. Small to medium size wasps (1–4 mm) with mesoscutum and metasomal tergites strongly arched in lateral view; apex of metasoma curved down; head strongly transverse; antennae inserted low on face, right above clypeus, antennal shelf not developed; scape about 2.5 times as long as wide; antenna of female 15-segmented and male 14-segmented; males with modified (sex-segment) A3 and A4, or only one of them, or both not modified; notauli reduced to anterior pits or completely developed; fore wing without stigma but with slightly thickened marginal vein; metatibia incrassate and covered with thick bristles; metasoma distinctly petiolate with tergum 2 the longest; ovipositor entirely retracted; males, and most females, with one-segmented exposed cerci on T8.

Remarks. Masner (1976, 1993) provided a detailed diagnosis of the genus Ismarus and Ismaridae in general, mainly based on morphological features such as: (1) female antennae 15-segmented, male antennae 14-segmented, with sex-segment usually being on A4, rarely on A3 or A3 and A4; (2) antennae with scape about 2.5 times as long as wide and inserted low on face, right above clypeus, antennal shelf not developed; (3) notauli always wanting, reduced to anterior pits; (4) mesosoma relatively short and highly convex dorsally, metasoma distinctly petiolate with tergum 2 the longest; (5) fore tibiae with regular spur and 1 false spur; (6) metatibia incrassate; (7) one-segmented cerci on T8 relatively long and not inserted in depressions in both sexes; (8) ovipositor entirely retracted. After Masner’s revision of the New World fauna of the genus, twenty-nine species of Ismarus were described ( Liu et al., 2011; Kolyada & Chemyreva, 2016; Kim et al., 2018a, b; Zhang et al., 2021; Yan et al., 2023). However, all diagnostic features remain universal for all known Ismarus species. Kim et al. (2018a) reasonably mentioned an additional character in the family and genus diagnosis: “base of second tergite with median furrow”. The two new species described below conform to all features of the Ismarus diagnosis, except for three: the presence of the median furrow at the base of T2, the presence of the false spur on the fore tibiae, and the absence of notauli. These peculiarities, along with other morphological specialties of the new species, justify their classification as a separate genus within the family Ismaridae .