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

description: Mesochorus (Mesochorus) longimurus nov. sp.
(Figs 3D, 10B, 18B, 22N)
Holotype. (♀) NW Vietnam: Tonkin, Hoang Lien N. R., 10 km SW Sa Pa, c. 1550 m, 22–29.x.1999, Malaise traps, C. v. Achterberg, RMNH´99 (Leiden).
Paratype. (♀) similar label (Leiden).
Etymology. The species name refers to the strong and long median ridge of the face.
Description. ♀: Body length 5.5 mm. Length of fore wing 4.9 mm.
Head. Flagellum with 36–38 flagellomeres; 1 st flagellomere 6.5–6.6 × longer than wide and 1.9 × longer than 2 nd flagellomere, 0.7–0.8 × as long as eye; 2 nd flagellomere 3.8 × longer than wide; preapical flagellomere 2.5 × longer than wide. Temple moderately and roundly narrowed behind eye, dorsally c 0.5 × as long as eye. OED 1.7 × and OOD 0.9 × ocellar diameter. Occipital carina complete medially. Frons smooth ventrally and punctate dorsally, with fine median ridge below anterior ocellus. Face (Fig. 10B) coarsely punctate, with strong central longitudinal ridge covering whole length of face, width 1.00–1.1 × combined length of face and clypeus and 0.90–1.0 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Malar space and ventral 2/3 facial orbit widely striate. Malar space 0.7 × as long as width of mandibular base. Mandible with two teeth, ventral tooth longer than dorsal tooth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.
Mesosoma. 1.6 × longer than high. Side of pronotum punctate dorsally, almost smooth ventrally. Mesoscutum densely punctate apico-centrally, lateral lobe with dense but superficial punctures. Scuto-scutellar groove smooth. Scutellum moderately convex, finely punctate, without lateral carina, not pointed apically. Mesopleuron with rather dense punctures fronto-dorsally and sparse punctures ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse punctures. Submetapleural carina slightly lamelliform. Propodeum (Fig. 18B) completely carinate. Area basalis triangular, 2 × longer than wide. Area superomedia 1.3–1.6 × longer than wide and 0.6–0.8 × as long as area petiolaris; anterior transverse carina (costula) reaching 3/10 of its length. Area petiolaris 1.3–1.4 × longer than wide. Hind femur 4.4–4.5 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.9 × longer than 2 nd hind tarsomere; hind claw with 3 basal teeth, mid tooth longest. Areolet pointed frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a slightly postfurcal by 0.1–0.2 × its length. Postnervulus intercepted basad its middle. Pterostigma 3.2 × longer than wide. Hind wing with 5 hamuli. Nervellus of hind wing slightly reclivous.
Metasoma. 1 st tergite 2.7 × longer than wide. Postpetiolus with few fine punctures. 2 nd tergite 1.2 × longer than wide, with few fine setiferous punctures. Thyridium roundish. Ovipositor sheath (Fig. 22N) sparsely pilose, 9.0–10.0 × longer than wide, 0.5 × as long as hind tibia and 0.8–0.9 × as long as hind metatarsus, slightly narrowed in apical 0.2.
Color. Flagellum blackish, scape yellowish ventrally. Face, clypeus and gena yellowish. Palps, mandible except teeth, malar space, facial orbit and ventral half of frontal orbit cream-yellow. Vertical orbit reddish. Frons medially, stemmaticum and occiput dorsally black. Pronotum cream-yellow, collar black. Mesoscutum black; scutellum black, margins ± reddish. Mesopleuron black dorsally, yellow ventrally. Metapleuron yellow, with large central black spot. Propodeum yellow; area basalis, area externa and area dentipara black. 1 st tergite black, red basally. 2 nd tergite black, with large triangular yellow spot in apical 2/3. Following tergites red (3 rd tergite of paratype with baso-lateral brown spots). Ovipositor sheath brown. Fore and mid coxae and trochanters cream-yellow; fore and mid legs otherwise yellow. Hind coxa yellow, with brown dorsal spot. Hind femur red; hind tibia red, narrowly infuscate basally and with brown apico-external stripe in paratype. Hind tarsus red. Pterostigma dark brown.
♁ unknown.
Taxonomical remark. With its black basal and pale apical tergites, this new species belongs to the declinans group sensu Schwenke (1999). It is characterized by widely striate facial orbit, strong median facial ridge, and longer ventral mandibular tooth.
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 19-20, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309