This species is named in honour of David Marques – outstanding naturalist, ornithologist and evolutionary biologist, and most of all esteemed colleague. His dedication to research, to the stewardship of our natural history collections, and to his family have been an inspiration to me ever since we first met. The species epithet is a masculine genitive singular noun.

Holotype: Switzerland • 1♀; Glarus, Linthal, Obersand, Melchplatz; 46.84°N, 8.9306°E; 2051m a.s.l.; 19–28 Jun. 2008; Hannes Baur, Seraina Klopfstein leg.; Malaise trap #3; GBIFCH 02040366 (at NMBE). Paratypes: • 5♀; [same data as holotype]; GBIFCH 02040367–02040371 (at NMBE) • 5♀; [same data as holotype]; NMB-HYMEN0005555–0005559 (at NMB) • 1♀; [same locality as holotype]; 10–19 Jun. 2008; GBIFCH 02040372 (at NMBE) • 2♀; [same locality as holotype]; 10–19 Jun. 2008; NMB-HYMEN0005560–0005561 (at NMB) • 3♀; Graubünden, Surses, Alp Flix, Clavania; 46.5203°N, 9.6564°E; 1987 m a.s.l.; 20 Jul.–25 Aug. 2008; Hannes Baur, Salome Steiner leg.; Malaise trap #2; GBIFCH 02040373–02040375 (at NMBE) • 4♀; [same data as previous]; NMB-HYMEN0005562–0005565 (at NMB) • 1♀; [same locality as previous]; 23–30 Jun. 2003; Hannes Baur leg.; Malaise trap #1; NMB-HYMEN0005566 (at NMB) • 1♀; [same locality as previous]; 4–20 Jun. 2008; Hannes Baur, Salome Steiner leg.; MalaiseTrap #2; GBIFCH 02040376 (at NMBE) • 1♀; Graubünden, Surses, NE of Sur; 46.5242°N, 9.6342°E; 1770m a.s.l.; 1–25 Sep. 2006; Hannes Baur, Seraina Klopfstein leg.; Malaise trap; NMB-HYMEN0005567 (at NMB) • 1♀; Graubünden, Surses, Alp Flix, Lai Neir; 46.5356°N, 9.6375°E; 1920 m a.s.l.; 15–27 Jul. 2006; Hannes Baur, Seraina Klopfstein leg.; Malaise trap; NMB-HYMEN0005568 (at NMB).

Diadegma davidmarquesi has a characteristic, small and posteriorly converging area superomedia, but this character can be difficult to judge without having a lot of comparative material at hand. The new species also has a strong dark mark at the base of the hind femur, which further strengthens the impression of a dark-and-light banded leg caused by the ivory hind tibia with the strong subbasal and apical bands. Such a strong darkening of the base of the hind femur otherwise only occurs in D. (Nythobia) fenestrale (Holmgren, 1860), from which the new species can be distinguished from by the shorter ovipositor (0.6–0.75 versus 0.95–1.05 in D. fenestrale), the smaller and posteriorly converging area superomedia, and the generally lower OOL (0.85–1.05 versus 1.0–1.35). Diadegma (Nythobia) semiclausum (Hellén, 1949) also often has a dark marking below on the hind femur, although it is usually rather weak. The new species can be distinguished from D. semiclausum by the dark front coxa (at most with base a bit darkened in the latter), dark scape (nearly always marked with yellow below), and the higher OOL (1.45 –1.80 versus 1.15–1.45). Furthermore, D. davidmarquesi generally has longer antennae (24–26 flagellomeres versus nearly always 23, very rarely 24) and a longer tergite 2 (1.3–2.1 times longer than wide, versus 1.15–1.35).

In Horstmann’s key (Horstmann 1969), this species runs to group III (species with deeply excised tergite 7 and ovipositor sheath shorter than hind tibia), and within the group to D. semiclausum (under the junior synonym D. eucerophagum Horstmann, 1969); see above for distinguishing features from that species. Among the group III species described after 1969, only two are similar to D. davidmarquesi in having the hind tibia ivory medially and tergite 6 not or weakly excised: Diadegma (Nythobia) hispanicum Horstmann, 1973 and D. (Nythobia) incompletum Horstmann, 1973, but both never have the fore coxa dark, never have a dark mark basoventrally on the hind femur, and the latter furthermore has the longitudinal carinae on the propodeum strongly reduced.

Body 5.2–6.1 (5.9) mm. Temple in lateral view 0.70–0.95 (0.85) times as long as eye, dorsally rather steeply, at mid-height of eye evenly and roundly constricted; OOL 0.85–1.05 (1.0), POL 1.4–1.8 (1.4); face 1.30–1.40 (1.35) times as wide as high, with strong coriaceous microsculpture against which punctures are disappearing, matt; malar space 0.70–0.90 (0.85) times width of mandible at base; clypeus a little rounded in profile, with weak microsculpture against which some punctures are visible; apical margin of clypeus somewhat impressed and reflexed as a weak lamella, especially laterally, margin slightly convex in frontal view. Antenna with 24–26 (26) flagellomeres, all of which longer than wide, tapering towards apex.

Pronotum coriaceous 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, with a few weak punctures indicated ventrally and anteriorly, smooth around speculum, anterior to it with longitudinal rugulae; metapleuron coriaceous and slightly shiny above.

Fore wing 3.6–4.4 (4.1) mm, areolet quadrate, small to medium-sized, weakly to strongly petiolate above, with vein 2m-cu meeting it clearly apically of middle. Hindwing with nervellus nearly vertical, weakly rounded, unbroken. Hind femur 4.6–5.2 (4.9) times as long as high; hind claw not much surpassing pulvillus in lateral view, with strong pecten reaching to more than half its length, nearly as long as claw itself.

Propodeum with carinae strong, coriaceous in area basalis, area externa and area superomedia, with rugae in area dentipara and strong, transverse rugae in area petiolaris; area basalis short, triangular, directly meeting area superomedial; area superomedia rather small, pentagonal with lateral sides clearly converging, shorter than to nearly as long as wide, posteriorly open to nearly closed by a transverse ruga; area petiolaris somewhat impressed medially.

Metasoma laterally compressed, widest around tergite 4 or 5, coriaceous sculpture becoming weaker towards apex where it ends up rather shagreened and with minute punctures around hair roots. Tergite 1 0.6–0.7 (0.6) times as long as hind tibia, with small, deep glymma at about halfway between base and spiracle, postpetiolus first rounded, then nearly flat dorsally. Tergite 2 1.30–2.10 (1.65) times longer than wide at apex, tergite 6 not or very weakly excised, tergite 7 deeply excised. Ovipositor sheath 0.60–0.75 (0.65) times as long as hind tibia, evenly upcurved, rather thin, with notch rather distant from apex, ventral valves with minute teeth.

Black; palps, mandibles except teeth, tegula, wing base, and all trochantelli light yellow; scape black; wing venation brown, pterostigma medium brown. All coxae black, fore and mid trochanters orange at base, remainder light yellow, hind trochanter black with yellow apex, all femora orange, hind femur with large black mark at base, especially ventrally, and often dorsally at apex; fore and mid tibiae orange, often ivory on outer side, mid tibia with indication of subbasal and apical brown bands, tarsi orange to brown; hind tibia on the inner side orange, on the outer ivory at base and medially, dark brown to black subbasally and apically; hind spurs and base of first tarsomere ivory, remainder dark brown. Metasoma entirely dark.

No host data is available to date for this species.

The species epithet is derived from the Latin word mīrum, meaning “wonderful” – which all of Earth’s creatures ultimately are. The species epithet is an adjective in neuter nominative singular form, as the genus name Diadegma is neuter.

Holotype: Switzerland • 1♀; Bern, Saanen, Krinnen; 13–14 Sep. 1969; Jacques Aubert leg.; GBIFCH 02040377 (at MZL). Paratype: Sweden • 1♀; Kalmar län, Öland, Borgholm, Alvara Dödevi; 57.1872°N, 17.068°E; 12 Jul. 2022; Seraina Klopfstein leg.; NMB-HYMEN0005569 (at NMB).

The new species is one of just five species in the genus in Europe that have the punctation on the lower mesopleuron stronger than the coriaceous background. Diadegma (Nythobia) integrator Aubert, 1970 and D. (Nythobia) rectificator Aubert, 1970 both have tergites 6 and 7 not or weakly excised, while D. (Neoangitia) aculeatum (Bridgman, 1889) has an ovipositor that is much longer than the hind tibia and shiny posterior tergites. The most similar species in Europe with rather strong punctation on the mesopleuron is D. (Nythobia) areolare (Holmgren, 1860), a species known to me only from a single specimen in the Thomson collection in Lund (marked by Jacques F. Aubert as “TYPE!?”). The new species can be distinguished from it by its medially orange hind tibia (ivory in D. areolare), the areolet being met by vein 2m-cu a little apically of its middle (clearly basally in D. areolare), and by the much shorter area superomedia (which is nearly twice longer than wide in D. areolare).

In Horstmann’s key (Horstmann 1969), this species runs to group III (species with deeply excised tergite 7 and ovipositor sheath shorter than hind tibia), and within the group to either D. (Nythobia) areolare, D. (Nythobia) tenuipes (Thomson, 1887), or D. (Nythobia) combinatum (Holmgren, 1860). While the first of these species is already excluded above, the remaining two have the punctures on the mesopleuron at most as conspicuous as the background sculpture. From D. tenuipes, D. mirum can be further distinguished by its dark fore coxa and trochanter (orange and yellow, respectively, in D. tenuipes) and the higher POL (1.80–1.95 versus 1.25–1.45 in D. tenuipes). The new species shares both these characters with D. combinatum but has its inner eye margins almost parallel ventrally (strongly converging in D. combinatum), a lower OOL (1.05–1.10 versus 1.35–1.50 in D. combinatum), and its ovipositor evenly upcurved (nearly straight in D. combinatum).

Among the group III species described since 1969, none has a medially orange hind tibia combined with an at least somewhat excised tergite 6 and dark-marked fore trochanters. However, D. (Nythobia) alpinator Aubert, 1970 meets all these criteria and was not included in the 1969 key. It was originally described as a subspecies of D. combinatum (Aubert 1970), later synonymized with that taxon by Horstmann (1973), and only thirty year later resurrected as a separate species (Horstmann 2013). The new species can be distinguished from D. alpinator by the more deeply excised tergite 6, the longer tergite 2 (1.40 versus 1.05–1.15 in D. alpinator), the more distinctly banded hind tibia, and the lower OOL (1.05–1.10 versus 1.25–1.40 in D. alpinator).

Measurements are based on the two females in the type series, with the value of the holotype repeated in brackets.

Body 5.1–6.3 (6.3) mm. Temple in lateral view 0.75 times as long as eye, strongly and roundly constricted; OOL 1.05–1.10 (1.05), POL 1.80–1.95 (1.95); face 1.25–1.30 (1.25) times as wide as high, with coriaceous microsculpture and distinct punctures, especially in lower part, matt; malar space 0.5–0.7 (0.7) times width of mandible at base; clypeus a little rounded in profile, with weak microsculpture and distinct punctures; apical margin of clypeus somewhat impressed and reflexed as a weak lamella, margin convex in frontal view. Antenna with 26–28 (28) flagellomeres, about as long as wide or slightly longer in apical third, tapering towards apex.

Pronotum above punctate on nearly smooth background, in lower half with longitudinal rugae, not bulging below mesoscutum, epomia rather long; mesoscutum coriaceous, with distinct punctures on entire surface; scuto-scutellar groove smooth; mesopleuron only weakly coriaceous, nearly smooth in most parts, with strong and dense punctures, smooth around speculum, anterior to it with longitudinal rugulae amidst the punctation; metapleuron largely smooth and with strong punctures.

Fore wing 3.25–4.60 (4.60) mm, areolet quadrate, medium-sized to large, strongly petiolate above, with vein 2m-cu meeting it a bit apically of its middle. Hindwing with nervellus nearly vertical, weakly rounded, unbroken. Hind femur 4.75–4.80 (4.80) times as long as high; hind claw not surpassing pulvillus in lateral view, with strong pecten reaching to more than half its length, a bit shorter than claw itself.

Propodeum with carinae strong, coriaceous in area basalis and area externa, rugulose in area dentipara and area superomedia, with transverse rugae in area petiolaris; area basalis short, triangular, directly meeting area superomedia; area superomedia of average size, long pentagonal with lateral sides slightly converging, a bit longer than wide, posteriorly open; area petiolaris very weakly impressed medially.

Metasoma laterally compressed, widest around tergite 2 or 3, coriaceous and with weak but dense punctures. Tergite 1 with small, deep glymma a bit closer to spiracle than to base, postpetiolus first rounded, then flat dorsally. Tergite 2 1.40–1.45 (1.40) times longer than wide at apex, tergites 6 and 7 deeply excised. Ovipositor sheath 0.85–0.90 (0.90) times as long as hind tibia, evenly upcurved, with notch rather distant from apex, ventral valve apparently smooth.

Black; palps, mandibles except teeth, tegula, wing base, and fore trochantellus yellow; scape black; wing venation brown, pterostigma medium brown. All coxae black; trochanters and mid and hind trochantelli black at base, narrowly yellow at apex; femora light to dark orange, ventrally marked with black at least at base; fore and mid tibiae orange, mid tibia with indication of subbasal and apical brown marks, tarsi orange to brown; hind tibia on the inner side orange, on the outer ivory at base, orange medially, dark brown to black subbasally and apically; hind spurs and base of first tarsomere orange to brown, remainder dark brown. Metasoma entirely black.

No host data is available for this species.

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.

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-HYMEN0005570 (at NMB). Paratype: Switzerland • 1♂; Graubünden, Bergün, Albulapass; 2300 m a.s.l.; 24 Mar. 2013; Jürg Schmid leg.; reared from Plutella geniatella; NMB-HYMEN0005571 (at NMB).

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).

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 2m-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).