Mesochorus (Mesochorus) vietnamensis, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 42-43

Mesochorus (Mesochorus) vietnamensis nov. sp.

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

Holotype. (♀) Vietnam, Lam Don / Khan Khoa border, 12°10,58 N 108°42,50 E, 1625 m, 19.IV.2010, leg. A. Prokofiev (coll. Riedel)

Description. ♀: Body length 5.1 mm.

Head. Flagellum slender and long, with 37 flagellomeres; 1 st flagellomere 7.8 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.7 × longer than wide; preapical flagellomere c 2.0 × longer than wide. Temple short, strongly and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 0.5 × and OOD 0.7 × ocellar diameter. Frons with microsculpture and rim between antennal sockets. Face ( Fig. 13H ) coarsely punctate, with central longitudinal ridge, width 1.0 × combined length of face and clypeus and 0.8 × eye length; inner eye margins slightly convergent ventrally. Subantennal transverse carina dipped medially. Malar space and mandible with fine striae. Malar space 0.4 × 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. Side of pronotum densely punctate dorsally. Mesoscutum coarsely and densely punctate centrally, shining. Mesopleuron ( Fig. 16H ) with dense coarse punctures, speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine dense punctures. Scutellum without lateral carina or apical tubercle, rounded in profile. Propodeum ( Fig. 20D ) completely carinate. Area basalis triangular, 2 × longer than wide. Area superomedia 1.5 × longer than wide and 1.1 × longer than area petiolaris; anterior transverse carina (costula) reaching its frontal 0.4. Area petiolaris 1.1 × longer than wide. Hind femur 4.9 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.4 × longer than 2 nd hind tarsomere; hind claw with 4 long teeth. Areolet pointed frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a interstitial.

Metasoma. 1 st tergite 3.3 × longer than wide. Postpetiolus with some short central rugae. 2 nd tergite 1.3 × longer than wide. Thyridium transverse-oval. Ovipositor sheath ( Fig. 24J ) densely pilose, 6.9 × longer than wide, 0.5 × as long as hind tibia and 0.8 × as long as hind metatarsus, moderately narrowed in apical 0.3.

Color. Antenna ochreous. Face blackish, with reddish central stripe. Palps, clypeus, mandible except teeth, ventral half gena, inner orbit up to anterior ocellus cream-yellow. Vertical and outer orbit reddish-yellow. Frons medially, stemmaticum and occiput blackish. Pronotum brownish, with wide yellow upper margin and narrow yellow ventral edge. Mesoscutum reddish, with H-shaped reddish-yellow mark; mesopleuron and scutellum red; propodeum and metapleuron blackish. Tergites black; 1 st tergite narrowly red basally. 2 nd and 3 rd tergites with diffuse reddish-brown shine. Legs yellow; hind tibia narrowly blackish at base and in apical 0.2. Pterostigma hyaline.

♁ unknown.

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.