Mesochorus (Mesochorus) pterostigmator, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 28-29

Mesochorus (Mesochorus) pterostigmator nov. sp.

( Figs 5C , 11F , 16F , 18I , 23I )

Holotype. (♀) N Vietnam: Hoa Binh, Hang Kia Pà Cò N. R. 1044 m, N 20°30´04´´ E 104° 56´44´´, 2.iii. –15.iv.2011, mal. tr. 4, C. v. Achterberg, RMNH´11 (Leiden).

Paratype. (♀) similar label (Leiden).

Etymology. The species name refers to unusually narrow pterostigma.

Description. ♀: Body length 4.1 mm. Length of fore wing 3.5 mm.

Head. Flagellum with 30 flagellomeres; 1 st flagellomere very slender, 9.6 × longer than wide and 1.8 × longer than 2 nd flagellomere, 0.8 × as long as eye; 2 nd flagellomere 4.7 × longer than wide; preapical flagellomere 2.0 × longer than wide. Temple moderately and roundly narrowed behind eye, dorsally 0.5 × as long as eye. OED 1.6 × and OOD 0.6 × ocellar diameter. Occipital carina complete medially. Frons punctate, with fine transverse aciculation opposite to lateral ocellus. Face ( Fig. 11F ) with dense but superficial punctures, with median longitudinal ridge in dorsal half, width 1.0 × combined length of face and clypeus and 1.0 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Malar space, mandible and entire facial orbit widely striate. Malar space 1.0 × as long as width of mandibular base. Mandible with two equal teeth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesosoma . 1.6 × longer than high. Mesoscutum rugose-punctate postero-medially, with dense but superficial punctures on lateral lobe. Scuto-scutellar groove smooth. Scutellum moderately convex, finely punctate, without lateral carina, apical margin somewhat pointed but without distinct apical tubercle. Mesopleuron ( Fig. 16F ) with sparse punctures fronto-dorsally and very sparse fine punctures ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine very sparse punctures. Submetapleural carina slightly lamelliform. Propodeum ( Fig. 18I ) completely carinate. Area basalis triangular, slightly longer than wide. Area superomedia 1.4 × longer than wide and 1.0 × as long as area petiolaris; anterior transverse carina (costula) reaching 4/10 of its length. Area petiolaris 1.1 × longer than wide. Hind femur 5.2 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.8 × longer than 2 nd hind tarsomere; hind claw with one short basal visible tooth. Areolet shortly sessile frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a postfurcal by 0.4 × its length. Postnervulus intercepted basad its middle. Pterostigma very narrow, 4.1 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite 3.2 × longer than wide. Postpetiolus smooth, with few punctures in apical half. 2 nd tergite 1.1 × wider than long. Thyridium transverse-oval. Ovipositor sheath ( Fig. 23I ) densely pilose, 8.3 × longer than wide, 0.5 × as long as hind tibia and 1.0 × as long as hind metatarsus, slightly narrowed from base to apex and slightly bent upwards.

Color. Flagellum and scape brownish; basal third of flagellum and pedicel ochreous. Face, reddish-yellow, with small paramedian black spots below antennal grooves. Frontal, vertical and outer orbits reddish-yellow. Palps, mandible except teeth, clypeus, malar space and wide facial orbit cream-yellow. Frons medially, stemmaticum and occiput dorsally black. Collar, mesoscutum, scutellum, metapleuron and propodeum black. Side of pronotum and tegula cream-yellow. Mesopleuron reddish, with large central black spot. 1 st tergite black, cream-yellow subbasally. 2 nd tergite black, with cream-yellow band in apical 0.2. 3 rd tergite black, with cream-yellow band in basal 0.1. Following tergites black, lateral ± cream-yellow. Sternites cream-yellow; 3 rd to 6 th sternites with small lateral brownish spots. Ovipositor sheath brown. Legs cream-yellow; hind coxa with brown dorsal spot; hind femur with brown stripes externally and internally; hind tibia blackish in basal 0.1 and apical 0.3, and with subbasal brown spot. Hind tarsus pale brownish. Pterostigma whitish-hyaline.

♁ unknown.

Taxonomical remark. This new species belongs to the group of Oriental Mesochorus species resembling M. tenebris nov. sp. by a typical color pattern of meso- and metasoma and its almost whitish pterostigma. It is closely related to or even conspecific with the Taiwanese Mesochorus monomaculatus Kusigemati, 1985 and differs only by some minor color differences.

Figures

FIGURE 5. Oriental Mesochorinae, habitus from lateral. A−Mesochorus paratenebris n. sp. HT, B−M. pictiloides n. sp. HT, C−M. pterostigmator n. sp., D−M. rufator n. sp. HT, E−M. sabahensis n. sp. HT, F−M. sapaensis n. sp. HT.

FIGURE 11. Oriental Mesochorinae, face from frontal. A− Mesochorus nigrofemur n. sp. HT (♀), B−M. nigrofemur n. sp. PT (♁), C−M. nigromaculatus n. sp. HT, D−M. paratenebris n. sp. HT, E−M. pictiloides n. sp. HT, F−M. pterostigmator n. sp., G−M. rufator n. sp. HT, H−M. sabahensis n. sp. HT.

FIGURE 16. Oriental Mesochorinae, mesopleuron from lateral. A−Orientochorus tonkinensis n. sp. HT, B−Mesochorus sulaensis n. sp. HT with juxtacoxal carina present, C−M. flavopronotalis n. sp. HT (♀), D−M. harlequinus n.sp. HT, E−M. malucutus n. sp. HT, F –M. pterostigmator n. sp. HT, G−M. tonkinesis n. sp. HT, H−M. vietnamensis n. sp. HT.

FIGURE 18. Oriental Mesochorinae, propodeum from dorsal. A− Mesochorus kinabaluensis n. sp. HT, B−M. longimurus n. sp. HT, C−M. longistylus n. sp. HT, D−M. malaysiacus n. sp. HT, E−M. malucutus n. sp. HT, F−M. nigripleuris n. sp., G−M. nigromaculatus n. sp. HT, H−M. pictiloides n. sp. HT, I−M. pterostigmator n. sp.

FIGURE 23. Oriental Mesochorinae, ovipositor sheath from lateral.A−Mesochorus longivalvator n. sp. HT, B−M. malaysiacus n. sp. HT, C−M. malucutus n. sp. HT, D−M. nigripleuris n. sp., E−M. nigrofemur n. sp. HT (♀), F−M. nigromaculatus n. sp. HT, G−M. paratenebris n. sp. HT, H−M. pictiloides n. sp. HT, I−M. pterostigmator n. sp., J−M. rufator n. sp. HT, K−M. sabahensis n. sp. HT, L−M. sapaensis n. sp. HT, M−M. semifuscus n. sp. HT, N−M. semipunctatus n. sp. HT.