Diadegma (Nythobia) orophilum Klopfstein, 2026, sp. nov.

Diadegma (Nythobia) orophilum sp. nov. Fig. 3 Etymology. The species epithet is derived from the Greek words oro- (ὄρος) for mountain and - philum (φίλος) for loving – the mountain-loving wasp. The species epithet is an adjective in neuter nominative singular form, as the genus name Diadegma is neuter. Material examined. Holotype: Switzerland • 1 ♀; Graubünden, Ilanz-Riein, Piz Riein; 2600 m a. s. l.; Aug. 2014; Jürg Schmid leg.; reared from Plutella geniatella Zeller, 1839; NMB - HYMEN 0005570 (at NMB). Paratype: Switzerland • 1 ♂; Graubünden, Bergün, Albulapass; 2300 m a. s. l.; 24 Mar. 2013; Jürg Schmid leg.; reared from Plutella geniatella; NMB - HYMEN 0005571 (at NMB). Diagnosis. The combination of a black hind femur and deeply excised tergites 6 and 7 is only shared by two other alpine species, D. alpinator and D. (Nythobia) ericinellae Horstmann, 2013. From both, it can be distinguished by the lower POL (~ 1.30 in the new versus 1.65–2.10 in the other two species) and the longer ovipositor (~ 1.05 versus 0.65–0.90). From D. alpinator, it can further be told apart by the hind tibia being ivory medially (versus orange brown in D. alpinator), the longer tergite 2 (1.60 versus 1.05–1.15), the more deeply excised tergite 6, and the lower OOL (~ 0.95 versus 1.25–1.40). From D. ericinellae, the new species differs also by the larger malar space (0.75 times as long as mandible at base, versus 0.50–0.55 in D. ericinellae). In Horstmann’s key (Horstmann 1969), D. orophilum runs to group IV (species with deeply excised tergite 7 and ovipositor sheath longer than hind tibia), and within the group to D. fenestrale. Besides the darker femora and trochanters, it can be distinguished from that species by the longer tergite 2 (~ 1.60 versus 1.20 – 1.45 in D. fenestrale), the lower OOL (~ 0.95 versus 1.00–1.40) and POL (~ 1.35 versus 1.60–2.00), the narrower clypeus, which is somewhat convex in cross-section, and the smaller and posteriorly converging area superomedia. Diadegma fenestrale has a large dark mark at the base and ventrally on the hind femur, but that mark never extends over the entire femur. Among the group IV species described after 1969, four species have the hind tibia ivory or light yellow medially, tergite 6 deeply excised and sometimes dark for coxae. Besides its mainly dark hind femur, the new species differs from these by the following characters: from D. (Neoangitia) albotibiale Horstmann, 1973 by the somewhat coriaceous microsculpture of the last tergites (nearly smooth and strongly shiny in D. albotibiale) and tergite 7 with excision v-shaped (wide and parallel-sided in D. albotibiale); from D. (Nythobia) nigridens Horstmann, 2008 by the yellow mandibles (conspicuously darkened in D. nigridens) and more narrow face (~ 1.25 versus 1.50–1.60 in D. nigridens); from D. (Nythobia) suecicum by the dark metasoma (with extensive orange markings laterally on most tergites in D. suecicum) and the shorter antennae (24–28 versus ~ 37 flagellomeres in D. suecicum); and from D. (Areolina) valesiator Aubert, 1970 by the metasoma shape (very strongly laterally compressed, almost knife-like in D. valesiator) and the shorter propodeum (elongate between hind coxae in D. valesiator). Description. As only one female and one male are available of this species, I give measurements of both sexes here, with the measurement of the female holotype repeated in the brackets. Body 5.3–5.8 (5.3) mm. Temple in lateral view 0.65–0.80 (0.65) times as long as eye, rather steeply and strongly constricted behind the eyes; OOL 0.90–1.0 (1.0), POL 1.30–1.35 (1.35); face 1.2 times as wide as high, with strong coriaceous microsculpture against which punctures are disappearing; malar space 0.75 times width of mandible at base; clypeus a little rounded in profile, clearly rounded in cross-section, rather weekly coriaceous and clearly punctured; apical margin of clypeus rather flat, convex in frontal view. Antenna with 24–28 (24) flagellomeres, weakly tapering towards apex, around last third with segments about as long as wide. Pronotum irregularly rugulose above, in lower half with longitudinal rugae, not bulging below mesoscutum, epomia short; mesoscutum coriaceous, at most with indistinct punctures on lateral parts; scuto-scutellar groove smooth; mesopleuron strongly coriaceous and with indistinct punctures in lower half, more shiny and rugulose with clear punctures in upper half, smooth around speculum, anterior to it with longitudinal rugulae; metapleuron rugulose and shiny with punctures indicated. Fore wing 4.05–4.20 (4.05) mm, areolet quadrate, medium-sized to large, weakly to strongly petiolate above, with vein 2 m-cu meeting it around its middle. Hindwing with nervellus nearly vertical, weakly rounded, unbroken. Hind femur 5.0–5.5 times as long as high; hind claw not much surpassing pulvillus in lateral view, with pecten reaching to about half its length, clearly shorter than claw itself. Propodeum with carinae strong, rugulose all over and with strong, transverse rugae in area petiolaris; area basalis short, triangular, meeting area superomedial in a short stalk; area superomedia rather small, pentagonal with lateral sides clearly converging, shorter than wide, posteriorly open; area petiolaris barely impressed medially. Metasoma laterally compressed, widest around tergite 3, coriaceous sculpture becoming weaker towards apex where it ends up rather shagreened and with minute punctures around hair roots. Tergite 1 0.6 times as long as hind tibia, with small, deep glymma a little closer to spiracle than to base, postpetiolus first rounded, then flat to a little concave dorsally. Tergite 2 1.55–1.65 (1.55) times longer than wide at apex, tergite 6 with deep but u-shaped, tergite 7 with deep, v-shaped excision. Ovipositor sheath 1.0 times as long as hind tibia, evenly upcurved, rather thin, with notch rather distant from apex, ventral valves apparently smooth. Black; palps, mandibles except teeth, tegula, wing base, and all trochantelli yellow, hind trochantellus with base black; scape black; wing venation dark brown, pterostigma medium brown. All coxae black, trochanters black with a narrow yellow apex; fore and mid femora orange, blackened ventrally and basally, hind femur black with a narrow orange apex; fore and mid tibiae orange, ivory on outer side, mid tibia with indication of subbasal and apical brown marks, tarsi orange to brown; hind tibia on the inner side brownish orange, on the outer ivory at base and medially, dark brown to black subbasally and apically; hind spurs and base of first tarsomere ivory, apex of spurs and remaining tarsomeres dark brown. Metasoma black, in both sexes with weak orange mark laterally on tergite 3. Both specimens in the type series have been reared from Plutella geniatella (Lepidoptera, Plutellidae), a species occurring exclusively at high altitudes (Baraniak 2007).