Mesochorus (Mesochorus) nigrofemur Riedel 2023, nov. sp.
Creators: name: Riedel, Matthias
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Mesochorus
Mesochorus nigrofemur

description: Mesochorus (Mesochorus) nigrofemur nov. sp.
(Fig. 4D, 11A, 11B, 23E)
Holotype. (♀) C. Vietnam: Ha Tinh, Vu Quang N.P., 106 m, N 18°17´41´´ E 105°25´42´´, 5.iii. –15.iv.2011, Mal. trap 14, C. v. Achterberg, RMNH´11 (Leiden).
Paratypes. (♀) similar label (coll. Riedel); (1 ♀, 2 ♁♁) NW Vietnam: Tonkin, Hoang Lien N. R., 15 km W Sa Pa, c. 1900 m, 15–21.x.1999, Malaise traps, C. v. Achterberg, RMNH´99 (Leiden).
Description. ♀: Body length 4.5–4.6 mm. Length of fore wing 4.0– 4.3 mm.
Head. Flagellum with 34–37 flagellomeres; 1 st flagellomere 6.2–6.5 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.1–4.2 × longer than wide; preapical flagellomere 2.5 × longer than wide. Temple short, strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 1.3–1.4 × and OOD 0.4 × ocellar diameter. Occipital carina complete medially. Frons smooth, with some coarse punctures dorsally. Face (Fig. 11A) coarsely punctate ventrally, rugose-punctate and with submedian impressions dorsally, with strong median ridge, width 1.0 × combined length of face and clypeus and 1.0 × eye length; inner eye margins parallel. Subantennal transverse carina strong, dipped medially. Malar space, mandible and ventral 0.2 of facial orbit striate. Malar space 0.8 × as long as width of mandibular base. Mandible with two teeth, ventral tooth slightly larger than dorsal tooth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.
Mesosoma. 1.6 × longer than high. Mesoscutum densely punctate, coarsely rugose-punctate apico-centrally. Scuto-scutellar groove finely punctate. Scutellum moderately convex, with sparse punctures, without lateral carina, not pointed apically. Mesopleuron with dense punctures fronto-dorsally, ventral part densely or rather densely punctate frontally but with fine sparse punctures posteriorly; speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse setiferous punctures. Juxtacoxal carina absent. Submetapleural carina low. Propodeum completely carinate. Area basalis triangular, with short apical stalk. Area superomedia 1.6 × longer than wide and 0.8 × as long as area petiolaris; anterior transverse carina (costula) reaching at 4/10 of its length. Area petiolaris 1.4 × longer than wide. Hind femur 4.6–4.9 × longer than wide; hind metatarsus 0.6 × as long as hind tibia; hind claw with c 3 basal teeth. Areolet shortly sessile frontally; vein 2m-cu proximad its middle. Vein 1cu-a postfurcal by 0.5 × its length. Pterostigma 2.9 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing slightly reclivous.
Metasoma. 1 st tergite slender, 3.3–3.6 × longer than wide. Postpetiolus with few median punctures. 2 nd tergite 1.0–1.1 × as wide as long. Thyridium transverse-oval. Ovipositor sheath (Fig. 23E) stick-shaped and slightly upcurved apically, 10.3–10.5 × longer than wide, 0.5 × as long as hind tibia and 0.8–0.9 × as long as hind metatarsus, with sparse setae distally.
Color: Flagellum black. Face, clypeus, scape, pedicel and outer orbit reddish. Palps, mandible except teeth, malar space, ventral gena, and facial orbit cream-yellow; stemmaticum and occiput dorsally black. Mesoscutum black, with two paramedian reddish stripes. Scutellum reddish, black fronto-medially. Propodeum black centrally, reddishbrown laterally and apically. Pronotum yellow, with lateral reddish-yellow stripe. Tegula yellow. Mesopleuron black or brown and reddish; metapleuron ± black. 1 st tergite black, its sternite reddish-yellow. 2 nd tergite black, with reddish-yellow spot with rounded frontal margin in apical 0.3. 3 rd tergite black. Following tergites brown dorsally, yellow laterally. Ovipositor sheath dark brown. Fore and mid coxae and all trochanters cream-yellow; fore and mid legs otherwise yellow. Hind coxa pale yellow, with black spot dorsally; hind femur reddish, with black stripes externally and internally; hind tibia cream-yellow, black in basal 0.2 and apical 0.3; hind tarsus black. Pterostigma dark brown.
♁: Body length 4.2–4.8 mm. Length of fore wing 4.1–4.2 mm.
Head. Flagellum with 34-35 flagellomeres; 1 st flagellomere 7.0–7.7 × longer than wide and 1.5 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.6–4.9 × longer than wide; preapical flagellomere 2.7 × longer than wide. Temple moderately and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 1.3–1.4 × and OOD 0.5–0.7 × ocellar diameter. Occipital carina complete medially. Face (Fig. 11B) coarsely punctate, with median ridge, width 0.9× combined length of face and clypeus and 0.9× eye length; inner eye margins parallel. Subantennal transverse carina strong, dipped medially. Malar space, mandible and ventral 0.4 of facial orbit striate. Malar space 0.6–0.7 × as long as width of mandibular base. Mandible with two teeth, ventral tooth slightly larger than dorsal tooth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.
Mesosoma. 1.6–1.7 × longer than high. Mesoscutum densely punctate, rugose punctate apico-centrally. Scutoscutellar groove smooth. Scutellum moderately convex, with sparse punctures, without lateral carina, not pointed apically. Mesopleuron with rather dense punctures fronto-dorsally, ventral part rather densely punctate frontally but with fine sparse punctures posteriorly; speculum smooth. Metapleuron with fine sparse setiferous punctures. Submetapleural carina low. Propodeum carinate as in ♀. Hind femur 4.7–4.9 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.8 × longer than 2 nd hind tarsomere; hind claw without visible teeth. Areolet pointed or shortly sessile frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a postfurcal by 0.1–0.2 × its length. Pterostigma 3.1–3.3 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.
Metasoma. 1 st tergite slender, 3.3–3.6 × longer than wide. Postpetiolus almost smooth. 2 nd tergite 1.2–1.3 × longer than wide. Thyridium transverse-oval. Paramere 0.8–0.9 × as long as hind metatarsus, distinctly clubbed apically.
Color. Flagellum black. Head reddish-yellow. Palps, mandible except teeth, malar space, ventral gena, clypeus and face entirely cream-yellow; stemmaticum and occiput dorsally black. Mesoscutum black, with H-shaped dark reddish central spot OR red, with two lateral and one median blackish stripe. Scutellum reddish, black frontomedially. Propodeum mainly black, reddish-brown apically. Pronotum and tegula cream-yellow. Mesopleuron reddish, sometimes brownish dorsally; metapleuron black. 1 st tergite black, its sternite reddish-yellow. 2 nd tergite black, with yellow triangular spot in apical 0.3. 3 rd tergite brown, with triangular yellow spot in basal 0.2–0.4. Fore and mid coxae and all trochanters cream-yellow; fore and mid legs otherwise yellow. Hind coxa yellow, with black spot dorsally; hind femur reddish, with black stripes externally and internally; hind tibia cream-yellow, black in basal 0.2 and apical 0.3; hind tarsus black. Pterostigma brown.
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 closely related to Mesochorus semifuscus nov. sp. (e. g. strong median ridge of face, longer ventral mandibular tooth, similar carination of propodeum and of form and length of ovipositor sheath), but differs mainly by darker coloration of the mesosoma and different color pattern of the metasoma.
description: Published as part of Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), pp. 1-72 in Zootaxa 5245 (1) on pages 24-25, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309