Mesochorus (Stictopisthus) flavator, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 12-13

Mesochorus (Stictopisthus) flavator nov. sp.

( Figs 2C , 9B , 22G )

Holotype. (♀) Indonesia: Sula Isl. , Mangole, near Buya, Mal. trap 16, c. 500 m, 2–22.iii.1996, C. v. Achterberg & Y. Yasir, RMNH (Leiden).

Etymology. The name refers to the mainly yellow (Latin: “flavus”) coloration of this species.

Description. ♀: Body length 3.5 mm. Fore wing 3.0 mm.

Head. Flagellum with 29 flagellomeres; 1 st flagellomere 4.5 × longer than wide and 1.4 × longer than 2 nd flagellomere, 0.5 × as long as eye; 2 nd flagellomere 2.9 × longer than wide; preapical flagellomere c 1.5 × longer than wide. Occipital carina complete medially. Temple moderately and roundly narrowed behind eye, dorsally c 0.5 × as long as eye. OED 2.2 × and OOD 0.5 × ocellar diameter. Frons with transverse microsculpture laterally, with weak longitudinal ridge below anterior ocellus and with two fine paramedian ridges between antennal sockets. Face ( Fig. 9B ) coarsely punctate, very wide, width 1.3 × combined length of face and clypeus and 1.2 × eye length; inner eye margins parallel. Subantennal transverse carina not dipped medially. Malar space and ventral 0.2 of facial orbit with fine striae. Malar space 0.9 × as long as width of mandibular base. Mandible rather slender, with two equal teeth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesosoma . Slightly depressed, 1.9 × longer than high. Side of pronotum largely smooth. Notaulus distinct in frontal 0.3 of mesoscutum. Mesoscutum with rather dense punctures apico-medially, shining. Mesopleuron with dense punctures fronto-dorsally and with rather dense punctures ventrally, speculum smooth. Dorsal end of epicnemial carina reaching frontal margin of mesopleuron Metapleuron densely punctate; juxtacoxal carina partly present. Scuto-scutellar groove narrow, c 4.0 × wider than long, smooth and without distinct ridges. Scutellum rounded in profile, with fine sparse punctures. Area basalis trapezoid, 1.5 × wider than long. Area superomedia wide, 1.2 × longer than wide and 0.85 × as long as area petiolaris, smooth; anterior transverse carina (costula) reaching its middle.Area petiolaris 1.2 × longer than wide. Hind femur 2.9 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 3.2 × longer than 2 nd hind tarsomere; hind claw without visible teeth. Areolet shortly sessile frontally, oblique; vein 2m-cu slightly proximad its middle. Vein 1cu-a postfurcal by 1.0× its length. Postnervulus intercepted in its middle. Pterostigma 2.9 × longer than wide. Distal part of RA (metacarp) long, about as long as width of pterostigma. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite stout, 2.2 × longer than wide. Postpetiolus with longitudinal rugae. 2 nd tergite 1.1 × wider than long. Thyridium comma-shaped. Ovipositor sheath ( Fig. 22G ) with sparse setae, 6.4 × longer than wide, 0.4 × as long as hind tibia and 1.0 × as long as hind metatarsus, moderately bent upwards apically.

Color. Body mainly reddish-yellow. Flagellum brownish, basal flagellomere ochreous. Mesosoma reddishyellow; side of pronotum ventrally yellow. Tergites yellowish; ovipositor sheath pale brown. Fore and mid coxae and all trochanters cream-yellow, legs otherwise yellow; hind tibia not distinctly infuscate apically; hind tarsus pale brownish. Pterostigma ochreous-hyaline.

♁ unknown.

Taxonomical remark. The species belongs to the subgenus Stictopisthus and is characterized by its yellow body color, wide face, slightly depressed mesosoma, smooth scuto-scutellar groove and small ocelli.

Figures

FIGURE 2. Oriental Mesochorinae, habitus from lateral. A−Mesochorus controversus n. sp. HT, B−M. diversidens n. sp. HT, C−M. flavator n. sp., D−M. flavopronotalis n. sp. HT, E−M. fuscomaculatus n. sp. HT, F−M. halmaherae n. sp. HT.

FIGURE 9. Oriental Mesochorinae, face from frontal. A− Mesochorus diversidens n. sp. paratype (PT) (♁), B−M. flavator n. sp. HT, C−M. flavopronotalis n. sp. HT (♀), D−M. flavopronotalis n. sp. PT (♁), E−M. fuscomaculatus n. sp. HT, F−M. halmaherae n. sp. HT, G−M. harlequinus n.sp. HT, H−M. kinabaluensis 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.