Mesochorus (Mesochorus) annamensis, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 8

Mesochorus (Mesochorus) annamensis nov. sp.

( Figs 1D , 8D , 17C , 22B )

Holotype. (♀) S Vietnam: Dak Lak, Chin Yang Sin N.P., Krong K´Mar, Mal.-trap 7-12, 760– 770 m, 21–26.x.2005, C. v. Achterberg & R. de Vries, RMNH´05 (Leiden).

Description. ♀: Body length 4.1 mm. Fore wing 3.2 mm.

Head. Flagellum slender, with 27 flagellomeres; 1 st flagellomere 7.0 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.4 × longer than wide; preapical flagellomere 2.5 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 1.7 × and OOD 0.5 × ocellar diameter. Occipital carina widely absent medially. Frons with microsculpture and sparse superficial punctures. Face ( Fig. 8D ) densely punctate, without central longitudinal ridge, width 1.1 × combined length of face and clypeus and 1.0 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Ventral 2/3 of facial orbit widely and malar space striate. Malar space 0.9 × as long as width of mandibular base. Mandible with two rather small equal teeth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesosoma . 1.6 × longer than high. Mesoscutum covered with dense short whitish setae, coarsely and densely rugose-punctate postero-medially, lateral lobe with dense punctures. Scutellum weakly convex, without lateral carina, not pointed apically. Mesopleuron with rather dense punctures fronto-dorsally and with sparse punctures ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse setiferous punctures. Submetapleural carina low. Juxtacoxal carina shortly present frontally and posteriorly. Propodeum ( Fig. 17C ) completely carinate.Area basalis triangular, longer than wide.Area superomedia 1.4 × longer than wide and 0.9 × as long as area petiolaris; anterior transverse carina (costula) reaching at 3/10 of its length. Area petiolaris large, 1.2 × longer than wide. Hind femur 4.2 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.7 × longer than 2 nd hind tarsomere; hind claw with 3 short basal teeth. Areolet shortly sessile frontally; vein 2m-cu proximad its middle. Vein 1cu-a postfurcal by 0.6 × its length. Postnervulus intercepted basad its middle. Pterostigma 2.9 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite 2.6 × longer than wide. Postpetiolus smooth, with sparse punctures. 2 nd tergite 1.2 x wider than long. Thyridium transverse-oval. Ovipositor sheath ( Fig. 22B ) completely pilose, stick-shaped, 11.1 × longer than wide, 0.7 × as long as hind tibia and 1.2 × longer than hind metatarsus.

Color. Head including face and clypeus reddish; palps, mandible except teeth, malar space and wide facial orbit cream-yellow; median stripe of frons and occiput dorsally brown; stemmaticum black. Flagellum brownish, scape and pedicel yellowish ventrally. Pronotum, tegula, mesopleuron and metapleuron cream-yellow, mesopleuron with brownish spot fronto-dorsally. Mesoscutum yellow, with lateral and antero-dorsal brown stripes. Scutellum yellow. Propodeum yellow; area basalis, area externa and area dentipara brown. 1 st tergite black, basally yellow, apically with narrow reddish spot. 2 nd tergite black, with triangular yellow spot in apical 0.5. 3 rd tergite brown, yellow laterally. 4 th to 6 th tergites yellow, with brownish dorsal spots. Fore and mid legs cream-yellow; hind coxa yellow, with brown dorsal spot; hind femur yellow, with ochreous stripe externally; hind tibia yellow, black in basal 0.1 and apical 0.3; hind tarsus except pale base of metatarsus blackish. Pterostigma brown.

♁ 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). It is characterized by the medially absent occipital carina and partly present juxtacoxal carina.

Figures

FIGURE 1. Oriental Mesochorinae, habitus from lateral. A−Orientochorus tonkinensis n. sp. HT, B−Astiphromma bicoloratus n. sp. HT, C−Mesochorus achterbergi n. sp. HT, D−M. annamensis n. sp. HT, E−M. brevipunctatus n. sp. HT, F−M. cariniscuta n. sp. HT.

FIGURE 8. Oriental Mesochorinae, face from frontal. A−Orientochorus tonkinensis n. sp. holotype (HT), B−Astiphromma bicoloratus n. sp. HT, C−Mesochorus achterbergi n. sp. HT, D−M. annamensis n. sp. HT, E−M. brevipunctatus n. sp. HT, F−M. cariniscuta n. sp. HT, G−M. controversus n. sp. HT, H−M. diversidens n. sp. HT (♀).

FIGURE 17. Oriental Mesochorinae, propodeum from dorsal. A−Orientochorus tonkinensis n. sp. HT, B−Astiphromma bicoloratus n. sp. HT, C−Mesochorus annamensis n. sp. HT, D−M. brevipunctatus n. sp. HT, E−M. cariniscuta n. sp. HT, F−M. diversidens n. sp. HT (♀), G−M. fuscomaculatus n. sp. HT, H−M. halmaherae n. sp. HT, I−M. harlequinus 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.