Mesochorus (Mesochorus) tonkinensis, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 41

Mesochorus (Mesochorus) tonkinensis nov. sp.

( Figs 7D , 13F , 16G, 20B, 24H)

Holotype. (♀) NW Vietnam: Tonkin, Hoang Lien N. R., 15 km W Sa Pa , c. 1900 m, 15–21.x.1999, Malaise traps, C. v. Achterberg, RMNH´99 (Leiden).

Description. ♀: Body length 6.3 mm. Length of fore wing 5.3 mm.

Head. Flagellum with 38 flagellomeres; 1 st flagellomere 6.3 × longer than wide and 1.7 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.2 × longer than wide; preapical flagellomere 2.4 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 0.7 × and OOD 0.4 × ocellar diameter. Frons finely aciculate laterally. Face ( Fig. 13F ) coarsely punctate, width 1.1 × combined length of face and clypeus and 0.9 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Malar space and ventral 0.2 of facial orbit weakly striate. Malar space 0.3 × 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 . 1.7 × longer than high. Mesoscutum densely punctate apico-centrally, lateral lobe with rather dense superficial punctures. Scutellum moderately convex, densely punctate, without lateral carina, not pointed apically. Mesopleuron ( Fig. 16G ) with dense punctures, speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with sparse punctures. Submetapleural carina low. Propodeum ( Fig. 20B ) completely carinate. Area basalis triangular, with long apical stalk. Area superomedia 2.2 × longer than wide and 1.7 × longer than area petiolaris; anterior transverse carina (costula) reaching at frontal 3/10 of its length. Area petiolaris about as long as wide. Tarsi slender; distal fore tarsomere 3.0 × longer than wide. Hind femur 5.1 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.5 × longer than 2 nd hind tarsomere; hind claw with 3 low basal teeth. Areolet pointed frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a interstitial. Pterostigma 3.2 × longer than wide. Hind wings with 6 (on left hind wing) or 5 (on right hind wing) distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite slender, 3.5 × longer than wide. Postpetiolus with superficial longitudinal ridges and rugae. 2 nd tergite 1.2 × longer than wide. Thyridium roundish. Ovipositor sheath ( Fig. 24H ) densely pilose, 7.6 × longer than wide, 0.4 × as long as hind tibia and 0.8 × as long as hind metatarsus, moderately narrowed in apical 0.3.

Color. Body reddish. Face yellowish. Palps, clypeus, mandible except teeth, malar space, ventral gena, and facial orbit cream-yellow. Hind edge of pronotum and tegula cream-yellow. Propleuron and ventral pronotum yellow. 1 st and 2 nd tergites reddish-yellow. 3 rd tergite reddish-yellow, yellowish in apical half. Following tergites yellow. Ovipositor sheath reddish. Fore and mid coxae and trochanters cream-yellow, legs otherwise yellow. Pterostigma hyaline, with darker anterior margin.

♁ unknown.

Taxonomical remark. This species belongs to the fulvus group sensu Schwenke (1999), e. g. body entirely reddish, without dark spots. It is characterized by its large ocelli, sparsely punctate ventral part of mesopleuron, and short basal pectin on hind claw. It also differs from M. rufator by smaller size, apically stalked area basalis, slenderer 1 st tergite, short and basally located pectination of hind claw, and stouter ovipositor sheath.

Figures

FIGURE 7. Oriental Mesochorinae, habitus from lateral.A−Mesochorus sumaterae n. sp. HT, B−M. templator n. sp. HT, C−M. tenebris n. sp., D−M. tonkinensis n. sp. HT, E−M. trani n. sp. HT, F−M. vietnamensis n. sp. HT.

FIGURE 13. Oriental Mesochorinae, face from frontal. A−Mesochorus sulaensis n. sp. HT (♁), B−M. sulaensis n. sp. PT (m#), C−M. sumaterae n. sp. HT, D−M. templator n. sp. HT, E−M. tenebris n. sp., F−M. tonkinensis n. sp. HT, G−M. trani n. sp. HT, H−M. vietnamensis 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 20. Oriental Mesochorinae, propodeum from dorsal. A−Mesochorus tenebris n. sp. HT, B−M. tonkinensis n. sp. HT, C−M. trani n. sp. HT, D−M. vietnamensis n. sp. HT.

FIGURE 24. Oriental Mesochorinae, ovipositor sheath from lateral. A−Mesochorus siamensis n. sp., B−M. stigmaticolor n. sp. HT, C−M. striatofacies n. sp. HT, D−M. sulaensis n. sp. HT, E−M. sumaterae n. sp. HT, F−M. templator n. sp. HT, G−M. tenebris n. sp., H−M.