Mesochorus (Stictopisthus) fuscomaculatus, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 14-15

Mesochorus (Stictopisthus) fuscomaculatus nov. sp.

( Figs 2E , 9E , 17G , 22I )

Holotype. (♀) C Vietnam: Ha Tinh, Vu Quang N.P., 141 m, N 18°17´39´´ E 105°25´30´´, 5.iii–15.iv.2011, Mal. trap 16, C. v. Achterberg, RMNH´11 (Leiden).

Paratypes. (♀) 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 (coll. Riedel); (♀) C Vietnam: Ha Tinh, Vu Quang N.P., 100 m, N 18°17´46´´ E 105°25´29´´, 5.iii. –15.iv.2011, Mal. trap 11, C. v. Achterberg, RMNH´11 (Leiden) .

Etymology. The species name refers to the brownish (Latin “fuscus” for “brownish”) maculae on the mesoscutum.

Description. ♀: Body length 3.6-4.0 mm. Fore wing 3.1-3.2 mm.

Head. Flagellum with 29 flagellomeres; 1 st flagellomere 4.9 × longer than wide and 1.4 × longer than 2 nd flagellomere, 0.6 × as long as eye; 2 nd flagellomere 3.7 × longer than wide; preapical flagellomere c 1.8 × longer than wide. Occipital carina complete medially. Temple distinctly and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 1.6 × and OOD 0.5 × ocellar diameter. Frons almost smooth medially and with microsculpture laterally, with shallow triangular elevation below anterior ocellus. Face ( Fig. 9E ) coarsely punctate, width 1.2 × combined length of face and clypeus and 1.1 × eye length; inner eye margins parallel ventrally. Subantennal transverse carina not dipped medially. Malar space and ventral 0.2 of facial orbit finely 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 . 1.8 × longer than high. Side of pronotum largely smooth, with few very sparse punctures. Notaulus indistinct. Mesoscutum densely punctate, shining, covered with rather long setae. Mesopleuron with dense punctures fronto-dorsally and with sparse to rather dense punctures ventrally, speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with sparse punctures. Scuto-scutellar groove rather large, 2.8 × wider than long, with c 4 weak longitudinal ridges. Scutellum rounded in profile, almost smooth. Propodeum ( Fig. 17G ) completely carinate. Area basalis trapezoid, about as long as wide. Area superomedia short, 1.7 × longer than wide and 0.9 × as long as area petiolaris, smooth; anterior transverse carina (costula) reaching its middle.Area petiolaris 1.1 × longer than wide. Hind femur 3.5-3.8 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.8 × longer than 2 nd hind tarsomere; hind claw with one visible basal tooth. Areolet shortly sessile frontally; vein 2m-cu slightly proximad or in its middle. Vein 1cu-a postfurcal by 1.0-1.2 × its length. Postnervulus intercepted in its middle. Pterostigma 2.9 × 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 strong longitudinal rugae. 2 nd tergite 1.3 × wider than long. Thyridium comma-shaped. Ovipositor sheath ( Fig. 22I ) with sparse setae, 8.1 × longer than wide, 0.6 × as long as hind tibia and 0.9-1.0 × as long as hind metatarsus, moderately bent upwards apically.

Color. Flagellum ochreous or pale brown. Head reddish-yellow. Face pale yellow; palps, mandible except teeth, malar space, facial orbit and ventral half of frontal orbit cream-yellow; occiput brown dorsally. Mesosoma reddishyellow; pronotum ventrally, hind edge of pronotum and tegula cream-yellow. Mesoscutum with lateral and anteromedial brown spots (in the paratype from trap 11 mesoscutum entirely yellowish); propodeum basally ± blackish. 1 st tergite black, basally and often apically cream-yellow. 2 nd tergite yellow, with black triangular anterolateral spots (medially confluent in holotype). 3 rd tergite brownish, basally and laterally yellowish. 4 th to 6 th tergites yellowish, with ± extended brown dorsal spots. Ovipositor sheath brown. Fore and mid legs including coxae cream-yellow; hind coxa cream-yellow, with reddish dorsal spot; hind femur reddish-yellow; hind tibia cream-yellow, black in apical 0.2-0.3; hind tarsus ± ochreous distally. Pterostigma pale grey-hyaline.

♁ unknown.

Taxonomical remark. The species belongs to the subgenus Stictopisthus and is characterized within this subgenus by its pale-yellow face, brownish color pattern of the mesosoma, and short area superomedia.

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 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.