Mesochorus (Mesochorus) nigromaculatus, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 25-26

Mesochorus (Mesochorus) nigromaculatus nov. sp.

( Figs 4F , 11C , 18G , 23F )

Holotype. (♀) C. Vietnam: Ha Tinh, Vu Quang N.P. 66 m, N 18°19´47´´ E 105°26´28´´, 4.iii. –15.iv.2011, Mal. trap 9, C. v. Achterberg, RMNH´11 (Leiden).

Description. ♀: Body length 4.5 mm. Length of fore wing 3.9 mm.

Head. Flagellum with 29 flagellomeres; 1 st flagellomere 5.4 × longer than wide and 1.4 × longer than 2 nd flagellomere, 0.6 × 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 c 0.2 × as long as eye. OED 1.5 × and OOD 0.5 × ocellar diameter. Occipital carina complete medially. Frons smooth, with dense punctures dorsally. Face ( Fig. 11C ) coarsely punctate, width 1.1 × combined length of face and clypeus and 1.1 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Malar space and ventral 2/3 of facial orbit widely striate. Malar space 0.8 × 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 . Rather stout, 1.5 × longer than high. Mesoscutum densely punctate apico-centrally, lateral lobe with rather dense but superficial punctures. Scutellum moderately convex, with sparse punctures, without lateral carina, not pointed apically. Mesopleuron with dense punctures fronto-dorsally and sparse punctures ventrally; speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with sparse punctures. Submetapleural carina slightly lamelliform. Propodeum ( Fig. 18G ) completely carinate. Area basalis triangular, 1.5 × longer than wide. Area superomedia 1.4 × longer than wide and 0.8 × as long as area petiolaris; anterior transverse carina (costula) reaching its middle. Area petiolaris 1.2 × longer than wide. Hind femur 4.3 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.8 × longer than 2 nd hind tarsomere; hind claw with 2 long basal teeth. Areolet pointed frontally; vein 2m-cu in its middle. Vein 1cu-a shortly postfurcal by 0.2 × its length. Postnervulus intercepted basad its middle. Pterostigma 3.0 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite 2.9 × longer than wide. Postpetiolus with short median impression and few punctures. 2 nd tergite 1.4 × wider than long. Thyridium transverse-oval. Ovipositor sheath ( Fig. 23F ) stick-shaped, sparsely pilose, 9.9 × longer than wide, 0.6 × as long as hind tibia and 1.1 × longer than hind metatarsus,

Color. Flagellum brown. Face, clypeus, scape, pedicel and outer orbit ochreous. Palps, mandible except teeth, malar space, ventral gena, and wide facial orbit cream-yellow; frons medially and occiput dorsally brown; stemmaticum black. Pronotum, tegula, mesopleuron and metapleuron cream-yellow; mesopleuron with frontodorsal brownish spot. Mesoscutum pale yellow, with two lateral and one antero-median black stripes. Scutellum pale yellow. Propodeum pale yellow; area basalis, area externa and area dentipara black. 1 st tergite black, basally and apical spot yellow. 2 nd tergite cream-yellow, with V-shaped black spot in basal half. 3 rd tergite brown, with yellow triangular spot in basal 0.4. Following tergites brown basally and yellow apically. Ovipositor sheath brown. Fore and mid legs cream-yellow. Hind coxa and trochanter cream-yellow, hind coxa with black spot dorsally. Hind femur ochreous, with brown stripes internally and externally; hind tibia yellow, blackish in basal 0.2 and apical 0.3; hind tarsus except ochreous base of metatarsus brown. Pterostigma brown, paler proximally and distally.

♁ 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 its widely striated facial orbit, rather long ovipositor sheath, and the color pattern of meso- and metasoma.

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 11. Oriental Mesochorinae, face from frontal. A− Mesochorus nigrofemur n. sp. HT (♀), B−M. nigrofemur n. sp. PT (♁), C−M. nigromaculatus n. sp. HT, D−M. paratenebris n. sp. HT, E−M. pictiloides n. sp. HT, F−M. pterostigmator n. sp., G−M. rufator n. sp. HT, H−M. sabahensis 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.