Third antennal segment 0.8–0.9 times as long as fourth segment (Fig. 11); subapical antennal segments of female slender (Figs 3, 10); face short, strongly transverse (2.7–4.0 times wider than high; Fig. 5); ventral margin of clypeus medially with one small acute tooth (Fig. 5) or truncately protruding (Fig. 16); third maxillary palp segment and second labial segment distinctly widened (Fig. 13); labial palp with 4 segments; mandible with transverse basal groove (Fig. 5); medio-ventral sulcus of propleuron strongly widened anteriorly (occupying nearly entire propleuron anteriorly) and reticulate; pronotum truncate medio-anteriorly; postpectal carina absent; hind wing with 3 distal hamuli; second submarginal cell of fore wing anteriorly narrowed and marginal cell of hind wing parallel-sided apically (Fig. 1); vein m-cu of fore wing antefurcal; first subdiscal cell of fore wing closed; vein 1-SR of fore wing absent and vein r distinctly longer than wide; vein cu-a of fore wing antefurcal, interstitial or narrowly postfurcal; vein 2A of fore wing slightly developed, short, area basal of vein largely glabrous (Fig. 8) and vein a absent (Fig. 1); tarsal claws simple (Fig. 12); first tergite parallel-sided or nearly so and dorsal carinae straight basally (Figs 4, 9); second tergite smooth or basally with some obsolescent sculpture.

Holarctic (two species).

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:

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.

Holotype, ♀ (BMNH), “England: Hants., Romsey, Awbridge, 1–14.viii.1981, C. & M. Vardy”, “Malaise trap at 5 m in dead Larix”, “Aspigonus sp., det. T. Huddleston, 1982”. Paratypes (2 ♀ + 1 ♂): 1 ♀ (RMNH), “England: Hants., New Forest, Minstead, 5.viii.[19]63. In cage with Apatele alni, L.W. Siggs”, “Aspidogonus sp., R.D. Eady det. 1967”; 1 ♀ + 1 ♂ (BMNH), “D. [= Germany], [near] Freiburg, Bechtaler Wald [= a strictly protected forest reserve near Weisweil in Baden-Württemberg], 1996”, “ex Ptilinus pecticornis”, “Hedqvist coll. BMNH(E) 2011-27”.

Clypeus with small acute tooth medio-ventrally (Fig. 5); face 4.0 times wider than high medially and with separate triangular area medially (Fig. 5); frons largely coriaceous (Figs 5, 6); malar suture present, except dorsal third (Fig. 5); hind coxa largely rugose dorsally (Fig. 7); mesosoma black or dark brown; length of first tergite about twice its apical width (Fig. 4); length of ovipositor sheath 1.2–1.3 times as long as fore wing (Figs 1, 14); length of fore wing 3.6–4.2 mm; antenna with 27–30 segments.

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.

Mesosoma. Length of mesosoma 1.5 times its height; dorsal pronope wide and moderately impressed, with pronotum truncate anteriorly (Fig. 2); antescutal depression absent, but with triangular flat area; pronotal sides largely punctate-rugose and medially crenulate; epicnemial area and complete precoxal sulcus widely reticulate-rugose and rest of mesopleuron (except dorsally) largely smooth; pleural sulcus crenulate; mesosternal sulcus wide and coarsely crenulate; notauli complete, crenulate and posteriorly wide (Fig. 2); middle lobe of mesoscutum densely punctate and posteriorly rugose, with a median carina, both lateral lobes largely smooth (Fig. 2); scutellar sulcus deep, wide and with irregular carinae; scutellum punctate and convex medially, with paired depressions medio-posteriorly (Fig. 2); surface of propodeum densely and coarsely rugose but anteriorly smooth, median carina short, posterior face hardly separated from dorsal face, lateral tubercles indistinct and areola absent.

Wings. Fore wing (Fig. 1): pterostigma triangular; first discal cell narrowly truncate anteriorly; 1-R1 ending before wing apex and 1.3 times as long as pterostigma; r:3-SR:SR1 = 9:13:74; 2-SR:3-SR:r-m = 28:13:22; 2-M nearly twice as long as 3-SR; r slender; 1-M and SR1 straight; cu-a interstitial; first subdiscal cell closed, CU1b short; M+CU1 sclerotized. Hind wing: M+CU:1-M = 24:15; cu-a straight.

Legs. Hind coxa densely rugose dorsally (Figs 7, 13); length of femur, tibia and basitarsus of hind leg 4.2, 8.7 and 8.4 times as long as wide, respectively; hind femur largely smooth; hind tibia slightly narrowed apically (Fig. 7); hind tibial spurs slender, apically acute and both 0.3 times as long as basitarsus.

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.

Colour. Black; antenna, clypeus, hind leg (but trochanter and trochantellus yellow), metasoma (but baso-ventrally yellowish-brown), pterostigma, parastigma and ovipositor sheath dark brown; remainder of legs (but middle coxa largely dark brown) and mandible brownish-yellow; veins brown; palpi, trochanters and trochantelli pale yellow; wing membrane slightly infuscate but somewhat darker near vein r of fore wing.

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 5.0–5.3 mm, fore wing 3.6–4.2 mm; antenna of female with 27 (1) or 28 (1) segments and of male 30 (1); first tergite 1.9–2.2 times as long as its apical width; ovipositor sheath 1.18–1.31 times 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.

Biology. Reared from Ptilinus pectinicornis (Linnaeus, 1758) (Coleoptera: Anobiidae: Ptilininae).

England, Germany.

Named after Colin and Martha Vardy, for collecting the holotype and for their hospitality during visits by the senior author.