A key to European species of Hyposoter Förster, 1869 (Ichneumonidae: Campopleginae) with descriptions of 18 new species, and notes on all included species Author Galsworthy, Anthony 0009-0009-6612-9847 acgalsworthy@btopenworld.com Author Shaw, Mark R. 0000-0002-6651-8801 markshaw1945@gmail.com Author Haraldseide, Håkon 0009-0009-6612-9847 acgalsworthy@btopenworld.com text Zootaxa 2023 2023-05-18 5290 1 1 73 http://dx.doi.org/10.11646/zootaxa.5290.1.1 journal article 53361 10.11646/zootaxa.5290.1.1 36037514-64e6-4cde-88f9-583b4b9d8bf1 1175-5326 7959256 FD54D381-F123-4958-A03E-6CA71E02D06A Hyposoter castaneus Galsworthy & Shaw sp. nov. ( Figs. 3–5 ) Diagnosis. Most specimens have the metasoma darkish brown, which is unusual in the genus and an immediately obvious distinguishing feature; but the metasoma can be more orange, and the species is therefore included twice in the key. Apart from the key characters, the species is distinguished by an unusually broad clypeus and face, which separate it readily from the otherwise quite similar (in some colour forms) H. caedator . The sculpture of the mesopleuron, with clear transverse rugae in front of a smooth speculum, is also distinctive. Description. Fore wing 3.5–4 mm . Head: face twice as broad as long, rugosely sculptured throughout, without evident punctures; clypeus short, curved at sides, similarly sculptured, with narrow, sharp, unsculptured apex; malar space equal to basal width of mandible; mandible tapering, with ventral flange narrow; genal carina complete, joining oral carina just short of base of mandible; frons and vertex rugosely sculptured, but less strongly than face; temples sharply narrowed behind eyes, very short, similarly sculptured; antenna slender, flagellum with 24–25 flagellomeres, first flagellomere 2.5x as long as wide. Mesosoma: epomia present; mesoscutum centrally with close-set deep punctures on a granulate background, lateral and posterior parts becoming strongly rugose; mesopleuron shining, but with faint linear sculpture throughout; groove in front of fovea strongly striate; anterior and ventral areas, and metapleuron, with strong, evenly spaced punctures on a granulate background; propodeum rather short and rounded; area basalis narrow, V-shaped; area superomedia closed, broader than long, 5-sided, with front lateral edges much longer than rear ones; costulae complete; area petiolaris broadly triangular; whole propodeum rugosely sculptured, most strongly on petiolar area; propodeal spiracle slightly oval. Wings narrow, 1 cu-a interstitial, areolet almost sessile to short-stalked with vein 2 rs -m entering well beyond middle, nervellus gently curved, almost vertical. Metasoma: first tergite with petiole narrowed before postpetiole, and ventral edge sinuate in lateral view; glymma obvious, but shallow; dorsolateral carinae present, but weak; postpetiole triangular, faintly granulate, with symmetrical depressions above and behind spiracles; tergite 2 strongly granulate to two thirds, its posterior part and other tergites only faintly sculptured, and with scattered fine punctures; tergite 6 with posterior border entire; ovipositor slightly longer than apical depth of metasoma, almost straight, with strong subapical notch. Colour: black; apex of underside of scape, mandibles other than extreme base and teeth (which are brown), tegulae, 2nd metasomal sternite yellow; femora, tibiae and fore and mid tarsi orange; hind tarsus brown, basitarsus pale at base; tergite 1 black; tergite 2 black, with posterior edge sometimes orange, tergite 3 orange to brown with orange wash; tergite 4 orange to pale brown; tergites 5 onwards dark brown. Holotype : ♀ , [UK] Santon Downham , Norfolk , TL818883, Malaise trap : heath with birch and pine, 25.7– 5.8.83, J.Field , RMSNH 1986.021 ( NMS ); paratypes : 1♀ , Chippenham Fen , Cambs, TL 650693, Malaise trap : carr at reedbed edge, 16–24.6.83, J.Field , RMSNH 1986.021; 1♀ , Catfield , Norfolk , TG379201, Malaise trap : abandoned wet meadow, R.T.J.Jarvis , 27.7.–10.8.84 RSMNH 1983.102 (all in NMS ); 2♀ , Merton Park , London SW 19, TQ2469, Malaise trap in garden, 12–19.vii.14, A.C.Galsworthy ( NHMUK ); 1♀ , [ Germany ] Augsburg , 4.vii.1959 , Hyposoter carbonarius ♀ det R.Bauer , [in Horstmann’s hand] Hyposoter ? insulator Aub. Horstm. 2013 ( ZSM ); 4♀ , Nürnberg [ Germany ], 7 & 11.7.76, 23.7.88, and 27.5.89, all labelled Hyposoter alienus Brke, R.Bauer (ZSM) ; 1♀ , Messkirch , Baden [ Germany ], 1.9.1969 , I.Wall , Hyposoter ? meridionellator Aubert det. Riedel , 2014 (private collection Matthias Riedel ). Male and biology unknown.