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

description: Mesochorus (Mesochorus) striatofacies nov. sp.
(Figs 6E, 12G, 12H, 19H, 24C)
Holotype. (♀) Malaysia: SE. Sabah, nr Danum Valley Field C, W8, Malaise trap 8, c 210 m, 14–20.iii.1987, C. v. Achterberg, RMNH´87 (Leiden).
Paratype. (♁) similar label (Leiden).
Etymology. The species name refers to the widely striated facial orbits.
Description. ♀: Body length 4.3 mm. Fore wing 3.6 mm.
Head. Flagellum with 30 flagellomeres; 1 st flagellomere 6.1 × longer than wide and 1.7 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 3.8 × longer than wide; preapical flagellomere 2.5 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 1.8 × and OOD 0.3 × ocellar diameter. Occipital carina complete medially. Frons almost smooth, few sparse punctures, slightly and transversely striate opposite of lateral ocellus. Face (Fig. 12G) densely punctate, with central longitudinal ridge dorsally, width 1.0 × combined length of face and clypeus and 1.0 × eye length; inner eye margins moderately divergent ventrally. Subantennal transverse carina dipped medially. Facial orbit very widely and malar space distinctly 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. Rather stout, 1.5 × longer than high. Mesoscutum coarsely and densely punctate, partly rugosepunctate. Scutellum moderately convex, without lateral carina, not pointed apically. Mesopleuron with rather dense punctures fronto-dorsally and very sparse punctures ventrally. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Metapleuron with fine sparse punctures. Submetapleural carina low. Juxtacoxal carina absent. Propodeum completely carinate. Area basalis triangular, shortly stalked apically. Area superomedia short, 1.4 × longer than wide and 0.6 × as long as area petiolaris; anterior transverse carina (costula) reaching at basal 0.4 of its length. Area petiolaris very large, 1.7 × longer than wide. Hind femur 4.1 × longer than wide; hind metatarsus long, 0.7 × as long as hind tibia and 3.0 × longer than 2 nd hind tarsomere; hind claw with 3–4 basal teeth. Areolet shortly sessile frontally; vein 2m-cu proximad its middle. Vein 1cu-a postfurcal by 0.2 × its length. Postnervulus intercepted basad its middle. Pterostigma 3.3× longer than wide. Hind wing with 4 distal hamuli, nervellus of hind wing vertical.
Metasoma. 1 st tergite rather stout, 2.3 × longer than wide. Postpetiolus smooth, with short central rim. 2 nd tergite 1.2 × wider than long. Thyridium transverse-oval. Ovipositor sheath (Fig. 24C) with sparse setae, stick-shaped, 10.7 × longer than wide, 0.6 × as long as hind tibia and 0.9 × as long as hind metatarsus.
Color. Face and clypeus reddish; palps cream-yellow. Wide inner and outer orbits, mandible except teeth and malar space yellow; median stripe of frons and occiput dorsally brown; stemmaticum black. Flagellum brownish, scape and pedicel yellowish. Pronotum, tegula, scutellum, mesopleuron and metapleuron yellowish; mesoscutum red, with 3 reddish-brown stripes; propodeum yellow, area basalis, area externa and basal half of area dentipara blackish. 1 st tergite black, reddish-yellow basally. 2 nd tergite black, with yellow band in apical 0.3. 3 rd and 4 th tergites brown, yellow laterally. 5 th to 7 th tergites brownish basally, yellow apically. Ovipositor sheath pale brown. Fore and mid legs pale yellow; hind coxa yellow, with brown dorsal spot; hind femur reddish-brown; hind tibia yellow, blackish in basal 0.2 and apical 0.3; hind tarsus brownish. Pterostigma brown.
♁: Body length 4.3 mm. Fore wing 3.6 mm.
Head. Flagellum with 32 flagellomeres; 1 st flagellomere 7.0 × longer than wide and 0.7 × as long as eye; 2 nd flagellomere 5.0 × longer than wide; preapical flagellomere 2.9 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 1.4 × and OOD 0.4 × ocellar diameter. Occipital carina complete medially. Frons punctate dorsally, smooth ventrally. Face (Fig. 12H) densely punctate, with central longitudinal ridge dorsally, width 1.0 × combined length of face and clypeus and 0.1 × eye length; inner eye margins almost parallel. Ventral 0.2 of facial orbit and malar space weakly striate. Malar space 0.8 × as long as width of mandibular base.
Mesosoma. 1.6 × longer than high. Mesoscutum coarsely and densely punctate, partly rugose punctate. Mesopleuron with dense punctures fronto-dorsally, ventrally with dense punctures in frontal part, but with sparse punctures in posterior part. Metapleuron with fine rather dense punctures. Propodeum (Fig. 19H) completely carinate. Area basalis trapezoid. Area superomedia short, 1.4 × longer than wide and 0.9 × as long as area petiolaris; anterior transverse carina (costula) reaching its middle. Area petiolaris 1.3 × longer than wide, with setiferous punctures. Hind femur 4.8 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.5 × longer than 2 nd hind tarsomere; hind claw with short basal teeth. Areolet shortly sessile frontally; vein 2m-cu proximad its middle. Vein 1cu-a postfurcal by 0.7 × its length. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.
Metasoma. 1 st tergite 2.8 × longer than wide. Postpetiolus with some rugae. 2 nd tergite as long as wide. Thyridium transverse-oval. Paramere 1.1× as long as hind metatarsus, clubbed apically.
Color. Darker than the ♀. Head reddish-yellow; palps, mandible except teeth, malar space, wide facial orbit, ventral part of frontal orbit cream-yellow; median stripe of frons and occiput dorsally brown; stemmaticum black. Flagellum brownish, scape and pedicel cream-yellow ventrally. Mesosoma reddish-yellow; collar and longitudinal stripe on mesopleuron brownish; mesoscutum with 3 black stripes; propodeum black in basal 2/3, reddish-brown in apical 1/3. 1 st tergite black, yellow basally. 2 nd tergite black, with triangular yellow spot in apical 0.3. Following tergites brown, yellowish laterally. Fore and mid legs pale cream-yellow; hind coxa yellowish; hind femur reddishbrown; hind tibia yellow, brown in basal 0.2 and apical 0.3; hind tarsus brownish. 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 characterized in ♀ by its widely striate facial orbit, apically pointed area basalis and very long area petiolaris. Although both sexes were collected together, the correlation is questionable due to some structural differences (facial orbit of ♀ widely but of ♁ not striate) and coloration (2 nd tergite of ♀ with apical yellow band but of ♁ with triangular yellow apical spot).
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 36-37, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309