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

description: Mesochorus (Mesochorus) stigmaticolor nov. sp.
(Figs 6D, 12F, 15A, 19G, 21A, 24B)
Holotype. (♀) 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).
Paratypes. (3 ♀♀) similar labels (Leiden and coll. Riedel).
Etymology. The species name refers to the characteristically bi-colored pterostigma.
Description. ♀: Body length 4.5–5.0 mm. Length of fore wing 4.5–4.7 mm.
Head. Flagellum with 31–32 flagellomeres; 1 st flagellomere 6.9 × longer than wide and 1.6 × longer than 2 nd flagellomere, 0.8 × as long as eye; 2 nd flagellomere 4.6 × longer than wide; preapical flagellomere 2.8–3.2 × longer than wide. Temple moderately and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 1.0 × and OOD 0.7 × ocellar diameter. Occipital carina complete medially. Frons with dense punctures and weak aciculation laterally. Face (Fig. 12F) coarsely punctate, without distinct longitudinal ridge, width 1.1 × combined length of face and clypeus and 1.0 × eye length; inner eye margins parallel or slightly divergent ventrally. Subantennal transverse carina dipped medially. Malar space and ventral 0.2–0.3 of facial orbit striate. Malar space 0.7 × 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. 1.7 × longer than high.Mesoscutum finely and densely punctate, partly rugose-punctate postero-medially. Scuto-scutellar groove smooth. Scutellum moderately convex, finely punctate, without lateral carina, not pointed apically. Side of pronotum with distinct fine punctation. Mesopleuron with dense coarse punctures fronto-dorsally and ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with finer and rather dense punctures. Juxtacoxal carina absent. Submetapleural carina low. Propodeum (Fig. 19G) completely carinate.Area basalis triangular or trapezoid, c 2 × longer than wide. Area superomedia 2.0 × longer than wide and 1.0–1.1 × as long as area petiolaris; anterior transverse carina (costula) reaching at 3/10 of its length. Area petiolaris 1.2 × longer than wide. Hind femur 5.2 × longer than wide; hind metatarsus 0.5–0.6 × as long as hind tibia and 2.4 × longer than 2 nd hind tarsomere; claws strongly modified, strongly bent basally and with elongate tips, almost falcate; hind claw (Fig. 21A) with 3 basal teeth, mid tooth very long and strong. Areolet pointed frontally; vein 2m-cu in its middle. Vein 1cu-a interstitial or slightly postfurcal by 0.1–0.2 × its length. Pterostigma (Fig 15A) 3.3 × longer than wide.
Metasoma. 1 st tergite slender, 3.3 × longer than wide. Postpetiolus with smooth, sometimes finely striate apically. 2 nd tergite 1.1–1.2 × longer than wide. Thyridium transverse-oval. Ovipositor sheath (Fig. 24B) densely pilose, 8.7–8.8 × longer than wide, 0.5 × as long as hind tibia and 0.9–1.0 × as long as hind metatarsus, stick-shaped.
Color. Antenna reddish-yellow, flagellum slightly infuscate distally.Head mainly reddish-yellow.Palps, mandible except teeth, malar space, ventral gena and facial orbit cream-yellow. Occiput ± brownish dorsally, sometimes also stemmaticum. Mesosoma reddish-yellow. Propleuron and side of pronotum ± brownish. Mesoscutum with two lateral and one fronto-median brownish stripes. Mesopleuron and metapleuron ± brown or black. Pronotum creamyellow, collar black. Mesoscutum black or black with two paramedian yellowish stripes (in paratype); scutellum black, margins ± reddish or yellow. Mesopleuron yellow, with blackish central spot or stripe. Metapleuron yellow, with large central black spot. 1 st and 2 nd tergites reddish or ± reddish-brown; 2 nd tergite with apical yellowish band or triangular spot. 3 rd yellowish, with reddish lateral stripe. Following tergites yellow. Ovipositor sheath yellowish. Fore and mid coxae and all trochanters cream-yellow; fore and mid legs otherwise yellowish. Hind coxa reddishyellow, sometimes with weak reddish-spot dorsally. Hind femur reddish-yellow; hind tibia yellow, basally and in apical 0.2 brown, usually with weak subbasal brownish spot. Hind tarsus yellow or ochreous. Pterostigma hyaline, with roundish brown spot in distal half.
♁ unknown.
Taxonomical remark. This new species belongs to the declinans group sensu Schwenke. Besides its typical color pattern of pterostigma, it is characterized by rather large ocelli and strongly modified claws which are almost falcate (as in males of the Palaearctic Mesochorus pelvis Schwenke (see Riedel 2018: 711, Fig. 42) bearing a very long mid 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 page 35, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309