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

description: 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.
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 14-15, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309