Revision of the genus Vadumasonium Kammerer (Hymenoptera, Braconidae, Brachistinae)

The genus Vadumasonium Kammerer, 2006 (Braconidae: Brachistinae: Diospilini), formerly known only from the Nearctic region, is revised and a second species is described from England and Germany: V. vardyorum sp. n. The genus is new to the Palaearctic region and we report the first host record for the genus. A key to similar genera of the Diospilini and to both species is given.


Introduction
The genus Vadumasonium Kammerer, 2006 (Braconidae: Brachistinae: Diospilini) hitherto comprised only the type species: Vadumasonium volatum (Mason, 1987), known from Missouri and Texas (U.S.A.; Yu et al. 2012).It was originally described in the genus Vadum Mason, 1987, but this is a junior homonym of Vadum Strusz, 1983, and was renamed by Kammerer (2006) as Vadumasonium.The second author discovered a similar species from England and Germany amongst unidentified Braconidae in the collections of the Natural History Museum (London), which is described in this paper.The main differences between the two known species concern the length of the ovipositor sheath, the shape of the clypeus and of the first metasomal tergite.The biology of the type species is unknown but a pair of paratypes from Germany was reared from Ptilinus pectinicornis (Linnaeus, 1758) (Coleoptera: Anobiidae: Ptilininae).This agrees with what is known about host relationships of Diospilini, which are koinobiont endoparasitoids of coleopterous larvae (Shaw and Huddleston 1991).The tribe Diospilini Foerster, 1862, was traditionally included in the Helconinae s.l., but recent research (Sharanowski et al. 2011) suggests placement in a separate subfamily, Brachistinae Foerster, 1862, together with the former Blacinae Foerster, 1862.
Notes.The genus Vadumasonium Kammerer belongs to a group of diospiline genera with vein 3-SR of fore wing shorter than vein 2-M (Fig. 1), resulting in an anteriorly narrowed (or trapezoidal) second submarginal cell; tarsal claws simple, without lobe or lamella (Fig. 12); dorsal carinae of first tergite strong in basal half of tergite and comparatively far from border of tergite (Figs 4, 9); hind wing with 3-5 distal hamuli; third antennal segment shorter than fourth segment (Fig. 11) or slightly longer.The genera can be separated as follows: 1 Medio-ventral sulcus of propleuron strongly widened anteriorly (occupying nearly entire propleuron anteriorly) and reticulate; mandible with transverse basal groove (Fig. 5); third antennal segment about 0.9 times as long as fourth segment (Fig. 11); ventral margin of clypeus with one small acute tooth (Fig. 5) or truncate protrusion (Fig. 16); third maxillary palp segment and second labial segment distinctly widened (Fig. 13); first tergite parallel-sided or nearly so (Figs Similar genera outside the Diospilini (Hellenius Tobias, 1982, in the Blacini) or the Brachistinae (Plesiotypus van Achterberg, 1992, in the Microtypinae) can be separated as they have vein 1-SR of the fore wing present, the ventral margin of the clypeus truncate or slightly convex and the precoxal sulcus absent or narrowly developed.In addition, Hellenius has the dorsal carinae of the first tergite curved basally and Plesiotypus has the pronotum concave medio-anteriorly and the face about 1.5 times wider than high medially.
Description.Holotype, ♀, length of body 5.0 mm, of fore wing 4.2 mm.Head.Antenna with 28 segments and 1.1 times as long as fore wing (Fig. 10); third segment 0.9 times as long as fourth segment, length of third, fourth and penultimate segments 3.6, 4.0 and 1.3 times their width, respectively; length of maxillary palp nearly equal to height of head; third segment of maxillary palp distinctly widened medially; second segment of labial palp wide, triangular with fourth segment inserted at lower corner (Fig. 13); occipital carina complete but medio-dorsally weakly developed; hypostomal carina narrow; length of eye in dorsal view 1.5 times temple (Fig. 6); frons moderately depressed and coriaceous medially, without median carina or groove and laterally slightly convex and punctate; face 4.0 times wider than high, slightly convex and punctate laterally and medially with triangular flat area (Fig. 5); clypeus convex and sparsely but distinctly punctate, its ventral margin thick and medio-ventrally with small tooth (Fig. 5); malar suture present, except dorsal 0.3 of malar space, malar space 1.2 times as long as basal width of mandible (Fig. 13); mandible with deep transverse groove basally (Fig. 5), ventral tooth about as wide as longer dorsal tooth.
Metasoma.First tergite 2.1 times as long as its apical width, surface largely rugose with straight dorsal carinae on basal 0.3 of tergite (Fig. 4); second suture absent; second and following tergites smooth; length of setose part of ovipositor sheath 1.18 times fore wing; upper valve of ovipositor depressed apically, without apical notch or nodus (Fig. 15); hypopygium truncate apically.
Male.The males do not differ from the females except for the sexual differences and a slightly higher number of antennal segments.
Variation.Length of body 5.0-5.3mm, fore wing 3.6-4.2mm; antenna of female with 27 (1) or 28 (1) segments and of male 30 (1); first tergite 1.9-2.2times as long as its apical width; ovipositor sheath 1.18-1.31times as long as fore wing; vein cu-a of fore wing interstitial or narrowly postfurcal; frons with or without an irregular median carina; second tergite smooth or with some obsolescent sculpture basally.
Etymology.Named after Colin and Martha Vardy, for collecting the holotype and for their hospitality during visits by the senior author.
. The specimens are deposited in the Natural History Museum, in London (BMNH), and in Naturalis Biodiversity Center, in Leiden (RMNH).