Genus Opazon Haliday, 1857

Opazon Haliday, 1857: 170 . Type species: Belyta (Opazon) parvula Haliday, 1857 .

Meuselia Kieffer, 1909 . Type species: Meuselia fuscicornis Kieffer, 1909 . Synonymised by Macek, 1995.

Promeuselia Kieffer, 1910 . Type species: Rhynchopsilus clausus Kieffer, 1908 . Synonymised by Nixon, 1957.

Rhynchopsilus Kieffer, 1908 . Type species: Rhynchopsilus apertus Kieffer, 1908 . Synonymised by Macek, 1995.

DIAGNOSIS.Small parasitoids (1.7–3.0 mm); pale brown to black. Head in frontal view with genae converging towards mouthparts; mouthparts hypognathous; mandibles beak-like, bidentate; clypeus strongly convex, higher than its width; labrum triangular; tentorial pits situated in deep depression; antennal shelf prominent, toruli close to each other. Female antenna 15-segmented, incrassate apically; male antenna 14- segmented with cylindrical antennomers and A3 mostly modified. Mesosoma usually a little higher than wide; pronotum with prominent pronotal shoulders, with sharp and distinct epomia; pronotal pits absent, epomia not interrupted; pronotal collar sculptured, often with distinct transversal keel; mesonotum convex with complete and deep notauli; propodeum slightly transverse with simple median keel; plicae distinct throughout and weakly projecting posteriorly. Venation with radial cell closed or partly open apically (Figs 14– 15); veins C, Sc, marginal, postmarginal, stigmal, radial and basal veins tubular; marginal vein longer than radial cell and distance from marginal vein to basal vein. Petiole subcylindrical, a little longer than wide, finely sculptured; T 2 with five deep and short grooves at base; S2 without any prominences anteriorly; female metasoma fusiform, compressed at posterior third, with pygidium extended and down curved; hypopygium enlarged, surmounting epipygium at sides; ovipositor long, as long as metasoma without petiole; gonapophyses slender.

RELATIONSHIPS. The genus Opazon belongs to Pantolytina subtribes and closely related to the genus Pantolyta Foerster, 1856, differing from it mainly by distinctly beak-like shape of mandibles. Moreover, the male genitalia of Opazon have apex of volsella fused with digitus, in difference from Pantolyta where volsella is free.

KEY TO PALAEARCTIC SPECIES OF OPAZON HALIDAY

1. A1 with weakly prominent lamellae in both sex (Figs 3, 4), slender, more than 6.0 times as long as wide in female and 5.0 in male. Mandibles 0.60–0.75 times as long as pleurostomal distance (Figs 3–4). Head in frontal view as height as wide (Figs 3–4); temples in dorsal view short (Fig. 16) ....................................................................... 2

— A1 with strongly prominent lamellae in both sexes (Figs 1, 2), robust, 3.6–4.5 times as long as wide in female (Figs 1–2) and 3.2–3.8 in male (Figs 9–10). Mandibles 0.82– 1.20 times as long as pleurostomal distance (Figs 1–2). Head in frontal view and temples in dorsal view elongate (Figs 1–2, 16, 18) ........................................................ 3

2. A11 and A 12 in females as wide as long to elongate; female antenna slender (Fig. 7); A 3 in males unmodified, straight (Fig. 12) ............. O. parvulum (Haliday, 1857)

— A11 and A 12 in females distinctly transverse; female antenna stout (Fig. 6); A 3 in males modified, strongly emarginate (Fig. 11) ............. O. frigidum Macek, 1995

3. Eyes prominent of outline of head in dorsal view. Mandible very long, longer than pleurostomal distance (Fig. 1) ............................................ O. apertum (Kieffer, 1908)

— Eyes not prominent of outline of head in dorsal view (Fig. 18). Mandible about as long as pleurostomal distance to weakly shorter (Fig. 2) ................................................... .................................. O. incrassatum (Thomson, 1859)

REMARK. Some difficulties in separation of O. parvulum and O. frigidum females are present. The females both species can be recognized in the Western Palaearctic fauna (Europe and west of the European part of Russia) using the key suggested by Macek [1995], but in the Eastern fauna (center and east of the European part of Russia, Ural, Siberia and Far East) the species better determinate by using characters described in the key above.