Mesochorus (Mesochorus) nigripleuris, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 23-24

Mesochorus (Mesochorus) nigripleuris nov. sp.

( Figs 4C , 10H , 18F , 23D )

Holotype. (♀) [green] Kinabalu Park, 6°5´N 116°33´E, Sorinsim, SW III 40 years; [white] SW III, B 3 , F 1 , 6.3.1997 A. Floren ( ZSM).

Etymology. The species name refers to the blackish meso- and metapleura.

Description. ♀: Body length 3.9 mm. Length of fore wing 3.0 mm.

Head. Flagellum with 29 flagellomeres; 1 st flagellomere 6.5 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.3 × longer than wide; preapical flagellomere 2.2 × longer than wide. Temple short, strongly and roundly narrowed behind eye, dorsally 0.3 × as long as eye. OED 1.5 × and OOD 0.7 × ocellar diameter. Occipital carina complete medially. Frons smooth, with fine rather dense punctures dorsally. Face ( Fig. 10H ) densely punctate ventrally, with strong median ridge, width 1.0 × combined length of face and clypeus and 0.9 × eye length; inner eye margins parallel. Subantennal transverse carina strong, dipped medially. Malar space, mandible and ventral 0.3 of facial orbit striate. Malar space 0.9 × as long as width of mandibular base. Mandible with two teeth, ventral tooth slightly larger than dorsal tooth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesosoma . 1.7 × longer than high. Mesoscutum densely punctate, punctures superficial on lateral lobe. Scutoscutellar groove smooth. Scutellum moderately convex, with sparse punctures, without lateral carina, not pointed apically. Mesopleuron with dense punctures fronto-dorsally and coarse but sparse punctures ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse punctures. Submetapleural carina low. Propodeum ( Fig. 18F ) completely carinate. Area basalis triangular, with apical stalk. Area superomedia 1.7 × longer than wide and 0.9 × as long as area petiolaris; anterior transverse carina (costula) reaching at 4/10 of its length. Area petiolaris 1.2 × longer than wide. Hind femur 4.1 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.6 × longer than 2 nd hind tarsomere; hind claw with one visible long basal tooth. Areolet shortly sessile frontally; vein 2m-cu in its middle. Vein 1cu-a postfurcal by 0.2 × its length. Postnervulus intercepted basad its middle. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite 2.5 × longer than wide. Postpetiolus with some rugae and striae in apical half. 2 nd tergite 1.2 × wider than long. Thyridium transverse-oval. Ovipositor sheath ( Fig. 23D ) continuously and distinctly narrowed towards apex, 12.7 × longer than wide, 0.6 × as long as hind tibia and 1.1 × longer than hind metatarsus, with sparse setae distally.

Color: Flagellum brown; basal flagellomeres, scape and pedicel ochreous. Head reddish; palps, mandible except teeth, malar space and facial orbit yellowish; stemmaticum black; frons medially and occiput dorsally brownish. Mesoscutum reddish-yellow, with blackish lateral stripes and brownish stripe medially. Scutellum reddish-yellow. Pronotum yellowish, with reddish-brown ventral spot. Mesopleuron, metapleuron and propodeum black. Hind edge of pronotum and tegula cream-yellow. 1 st tergite black, red basally. 2 nd tergite black, with large halfmoon-shaped yellowish spot in apical 0.5. 3 rd tergite black, with triangular yellow spot in basal 0.3. Following tergites brown. Ovipositor sheath brown. Legs yellow; hind tibia cream-yellow, blackish in basal 0.2 and apical 0.3; hind tarsus blackish. Pterostigma brownish.

♁ unknown.

Taxonomical remark. With its sessile areolet, postfurcal vein 1cu-a, slender and long ovipositor and short area superomedia, this species belongs to the dispar group sensu Schwenke (1999). It is characterized by the dark mesopleuron, stalked area basalis and continuously and strongly narrowed ovipositor sheath.

Figures

FIGURE 4. Oriental Mesochorinae, habitus from lateral. A−Mesochorus malaysiacus n. sp. HT, B−M. malucutus n. sp. HT, C−M. nigripleuris n. sp., D−M. nigrofemur n. sp. HT (♀), E−M. nigrofemur n. sp. PT (♁), F−M. nigromaculatus n. sp. HT.

FIGURE 10. Oriental Mesochorinae, face from frontal. A− Mesochorus lamdongensis n. sp. HT, B−M. longimurus n. sp. HT, C−M. longistylus n. sp. HT, D−M. longistylus n.sp. (frons from dorsal), E−M. longivalvator n. sp. HT, F−M. malaysiacus n. sp. HT, G−M. malucutus n. sp. HT, J−M. nigripleuris 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.