Mesochorus (Mesochorus) lamdongensis, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 18-19

Mesochorus (Mesochorus) lamdongensis nov. sp.

( Figs 3C , 10A , 22M )

Holotype. (♀) S Vietnam: Lam Dong, Bidoup Nuiba N.P., nr. Da Lat , Mal. trap 1-12, 1650–1700 m, 11–19.x.2005, C. v. Achterberg & R. de Vries, RMNH´05 (Leiden).

Paratype. (♀) N. Vietnam: Vinh Phuc, Tam Dao , 1050–1175 m, 14–17.vi.2007, Mal. traps, C. v. Achterberg & R. de Vries, RMNH´07 (Leiden) .

Etymology. The species name refers to the Vietnamese province Lam Dong where the holotype was collected.

Description. ♀: Body length 2.5 mm. Length of fore wing 2.2 mm.

Head. Flagellum with 23-24 flagellomeres; 1 st flagellomere 5.3 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.6 × as long as eye; 2 nd flagellomere 3.6–3.9 × longer than wide; preapical flagellomere 2.1 × longer than wide. Temple moderately and roundly narrowed behind eye, dorsally 0.6× as long as eye. OED 1.8–2.0 × and OOD 1.0 × ocellar diameter. Occipital carina apparently complete medially. Frons smooth, with microsculpture dorsally. Face ( Fig. 10A ) densely punctate, without median longitudinal ridge, width 1.0–1.1 × combined length of face and clypeus and 0.8–0.9 × eye length; inner eye margins slightly convergent ventrally. Subantennal transverse carina dipped medially. Malar space and ventral 2/3 of facial orbit striate. 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 . Stout, 1.5 × longer than high. Mesoscutum rather densely punctate apico-centrally, lateral lobe with superficial punctures. Scuto-scutellar groove distinctly striate. Scutellum moderately convex, with sparse punctures, without lateral carina, not pointed apically. Pronotum with some rugae ventrally. Mesopleuron with few rather dense punctures fronto-dorsally and very sparse punctures ventrally; speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse punctures. Submetapleural carina low. Propodeum completely carinate. Area basalis triangular, about as long as wide. Area superomedia 1.6 × longer than wide and 0.8 × as long as area petiolaris; anterior transverse carina (costula) reaching its middle. Area petiolaris 1.4 × longer than wide. Hind femur 4.2 × longer than wide. Hind tarsus short; hind metatarsus 0.4 × as long as hind tibia and 2.8 × longer than 2 nd hind tarsomere; hind claw without visible teeth.Areolet pointed frontally; vein 2m-cu in its middle. Vein 1cu-a postfurcal by 0.2–0.4 × its length. Pterostigma 2.9 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing interstitial.

Metasoma. 1 st tergite 2.4 × longer than wide. Postpetiolus with longitudinal striation. 2 nd tergite 1.6–1.8 × wider than long. Thyridium comma-shaped. Ovipositor sheath ( Fig. 22M ) stick-shaped, with sparse setae, 7.5–7.8 × longer than wide, 0.5 × as long as hind tibia and 1.2 × longer than hind metatarsus.

Color: Flagellum brown, basal flagellomeres ochreous; scape and pedicel yellowish. Head reddish-yellow; face and clypeus yellow. Palps, mandible except teeth, malar space and facial orbit cream-yellow; stemmaticum black; occiput dorsally brown. Tegula cream-yellow. Mesosoma reddish; propleuron and pronotum ventrally yellow; mesoscutum with lateral and fronto-median chestnut-red stripes; mesopleuron red, with chestnut-red posterior diffuse spot; metapleuron and propodeum brown, propodeum reddish-brown apically. 1 st tergite black, red basally. 2 nd tergite black, with rounded yellow spot in apical 0.3. 3 rd tergite brown, with yellow basal spot. Following tergites brown, with narrow pale hind margins. Ovipositor sheath brown. Fore and mid legs entirely cream-yellow. Hind leg yellow; hind tibia yellow, blackish in apical 0.2. Pterostigma ochreous-hyaline, margins darker.

♁ unknown.

Taxonomical remark. With its sessile areolet, postfurcal vein 1cu-a, stick-shaped ovipositor and short area superomedia, this species belongs to the dispar group sensu Schwenke (1999).

The species is characterized by its stout mesosoma and short hind tarsus, mainly brown apical tergites with narrow paler apical margins, and striated scuto-scutellar groove and postpetiolus.

Figures

FIGURE 3. Oriental Mesochorinae, habitus from lateral.A−Mesochorus harlequinus n. sp. HT, B−M. kinabaluensis n. sp. HT, C−M. lamdongensis n. sp., D−M. longimurus n. sp. HT, E−M. longistylus n. sp. HT, F−M. longivalvator 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 22. Oriental Mesochorinae, ovipositor sheath from lateral. A−Orientochorus tonkinensis n. sp. holotype (HT), B−Mesochorus annamensis n. sp. HT, C−M. brevipunctatus n. sp. HT, D−M. cariniscuta n. sp. HT, E−M. controversus n. sp. HT, F−M. diversidens n. sp. HT, G−M. flavator n. sp. HT, H−M. flavopronotalis n. sp. HT, I−M. fuscomaculatus n. sp. HT, J−M. halmaherae n. sp. HT, K−M. harlequinus n.sp. HT, L−M. kinabaluensis n. sp. HT, M−M. lamdongensis n. sp. HT, N−M. longimurus n. sp. HT.