1a-b: Pediobius foveolatus (Crawford) mesosomal dorsum (left), and propodeum (right)
2a-b: Pediobius propodea: P. adelphae Peck (left), and P. nigritarsis (Thomson) (right)
3a-b: Pediobius alcaeus (Walker) dorsal view (left), and lateral view of propodeum (right)
Pediobius face (left), and gaster (right)
Comments: Large genus linked with the Horismenus group and Paracrias. The posteriorly split median carina sometimes forms part of a median raised smooth strip, which recalls the median groove of Horismenus, and the mesepisternum has a frequently indistinct special projection set off by a dorsal sulcus and extending to overlap the posterior border of the prepectus, that is a defining apomorphy of the Horismenus genus-group. Also, some species have an apparent pit on the dorsal part (anterior half) of the scutellar-axillar border, another defining apomorphy of the Horismenus group. Less convincing characters that they all share are the very short postmarginal and stigmal veins, very long marginal vein, scrobal grooves present as distinct sulci, and general body form, sclerotization, and sculpture. It is difficult to point out unique apomorphies linking this genus to Paracrias, Emersonella, and especially to Entedon, although they share certain characters mentioned above, such as the scrobal grooves present as distinct sulci and relative lengths of the forewing veins, that are nevertheless highly variable in Entedon and a number of other apparently related genera. All of these genera, except many species of Entedon, also have a strong, sharp projection extending laterally from the metapleuron. I have found this character to be helpful in identification in some cases, but it is too variable to be used as a convincing apomorphy, as it is present in large-bodied Chrysocharis as well, but absent from most species of that genus.
Proacrias: Upper mesepimeron without extension over posterior border of prepectus. First gastral tergite collapsing in air-dried specimens, not more rigid than the other tergites. First gastral sternite without the ventral punctulate region at petiolar base.
Emersonella: Propodeum with semicircular submedian carinae, most broadly separated in middle of propodeum; anterior ends of the submedian carinae arising from broad pits or sunken areas with longitudinal rugae extending from the anterior propodeal margin. Face almost always entirely smooth. Transverse frontal groove nearly straight; scrobal grooves uniting before reaching transverse groove. Only resembling Pediobius in having a pair of submedian propodeal carinae, differing strongly in other features, including superficial aspects of body form and sculpture.
Edovum: Petiole with longitudinal ribs. Scutellum with median longitudinal groove; epicnemial carina present, extending from posterior edge of mesepisternal extension.
Horismenus: Vertex not carinate (though rarely with a small transverse ruga at the top of the rounded vertex). Scutellum with longitudinal groove in most species. Propodeum always with broad, smooth, raised median strip flanked by sunken channels, never with submedian or median carinae.
Paracrias: Petiole without dorsal flange. Lateral ocelli in all species very close to the vertex margin. Scrobal grooves uniting before reaching transverse frontal groove. Pronotal collar never carinate. Propodeum almost always with broad, smooth, raised median strip flanked by sunken channels; nucha long and conspicuous and/or propodeum divided into anterior and posterior halves by a distinct cross-carina, the posterior half rugulose in contrast to the mostly smooth anterior half.
Entedon: Propodeum with single narrow median carina placed in a more or less distinct recessed channel; plicae absent; channel between median panels and supracoxal flange crossed by distinct costulae. Scrobal grooves (when distinct) uniting before reaching transverse frontal groove.
Achrysocharoides: Some species have paired propodeal carinae, but differ from Pediobius in that they have a much smaller petiole without an anterior flange. Very few species with a pronotal collar or propodeal plicae.
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Boucek, Z. 1965. Studies of European Eulophidae, IV: Pediobius Walk. and two allied genera (Hymenoptera). Acta Entomologica Musei Nationalis Pragae. 36: 5-90.
Hansson, C. 2002. Eulophidae of Costa Rica (Hymenoptera: Chalcidoidea), 1. Memoirs of the American Entomological Institute 67.
Peck, O. 1985. The taxonomy of the Nearctic species of Pediobius (Hymenoptera: Eulophidae), especially Canadian and Alaskan forms. Canadian Entomologist. 117: 647-704.
Schauff, M.E. 1991. The Holarctic genera of Entedoninae (Hymenoptera: Eulophidae). Contributions of the American Entomological Institute 26.
Image credits: 1a-b, 3b: Schauff (1991). 2a-b, 3a: Boucek (1965).