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

description: Mesochorus (Mesochorus) diversidens nov. sp.
(Figs 2B, 8H, 9A, 17F, 22F)
Holotype. (♀) Indonesia: Sula Isl., Mangole, near Buya, Mal. trap 17, c 440 m, 13.x–2.xi.1993, C. v. Achterberg, RMNH´93 (Leiden).
Paratype. (♁) Indonesia: Sula Isl., Mangole, near Buya, Mal. trap 15, c 490 m, 2–22.iii.1995, C. v. Achterberg & Y. Yasir, RMNH (Leiden).
Etymology. The species name refers to the unequal mandibular teeth.
Description. ♀: Body length 3.6 mm. Fore wing 3.1 mm.
Head. Flagellum with 32 flagellomeres; 1 st flagellomere 7.3 × longer than wide and 1.6 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.7 × longer than wide; preapical flagellomeres 2.6 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 1.5 × and OOD 0.7 × ocellar diameter. Occipital carina complete medially. Frons smooth ventrally and with fine transverse striation and sparse punctures dorso-laterally. Face (Fig. 8H) densely punctate, with strong longitudinal ridge medially, width 1.0 × combined length of face and clypeus and 0.9 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Ventral 0.4 of facial orbit widely, malar space and mandible striate. Malar space 0.8× 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. 1.7 × longer than high. Mesoscutum densely punctate. Scuto-scutellar groove smooth. Scutellum moderately convex, with very sparse punctures, without lateral carina, not pointed apically. Side of pronotum almost smooth. Mesopleuron with 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 slightly lamelliform. Propodeum (Fig. 17F) completely carinate. Area basalis triangular, widely stalked apically. Area superomedia 1.7 × longer than wide and 0.9 × as long as area petiolaris; anterior transverse carina (costula) reaching at 3/10 of its length. Area petiolaris large, 1.5 × longer than wide. Hind femur 4.3 × longer than wide; hind metatarsus 0.6 × as long as hind tibia and 2.7 × longer than 2 nd hind tarsomere; hind claw without visible teeth. Areolet pointed frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a postfurcal by 0.2 its length. Postnervulus intercepted basad its middle. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.
Metasoma. 1 st tergite 3.1 × longer than wide. Postpetiolus smooth, with some sparse punctures. 2 nd tergite 1.1 × longer than wide. Thyridium comma-shaped. Ovipositor sheath (Fig. 22F) sparsely pilose in apical half, stickshaped and slightly bent upwards in apical 0.3, 10.5 × longer than wide, 0.5 × as long as hind tibia and 0.9 × as long as hind metatarsus.
Color. Flagellum brownish; scape, pedicel and two basal flagellomeres ochreous. Head reddish-yellow. Palps cream-yellow. Mandible except teeth, malar space, facial orbit and ventral half of frontal orbit pale yellow. Stemmaticum black. Mesosoma reddish, propodeum slightly darker red. Ventral spot and hind edge of pronotum, tegula pale yellow. 1 st tergite brown, red basally, with reddish-brown spot apically. 2 nd tergite brown, with yellow band in apical 0.25. 3 rd tergite brown, with narrow basal yellow band. Following tergites brown dorsally and yellow laterally. Ovipositor sheath brownish. Fore and mid coxae and trochanters cream-yellow. Fore and mid legs otherwise yellow. Hind leg reddish; hind tibia yellowish, slightly infuscate basally and blackish in apical 0.3. Hind tarsus except ochreous base of metatarsus brownish. Pterostigma brown.
♁: Body length 3.1 mm. Fore wing 2.9 mm.
Head. Flagellum with 30 flagellomeres; 1 st flagellomere 7.7 × longer than wide and 1.6 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.7 × longer than wide; preapical flagellomeres 2.9 × longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c 0.3 × as long as eye. OED 1.3 × and OOD 0.4 × ocellar diameter. Occipital carina complete medially. Frons smooth ventrally and with sparse punctures dorsolaterally. Face (Fig. 9A) densely punctate, with longitudinal ridge medially, width 0.9 × combined length of face and clypeus and 0.9 × eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Ventral 0.4 of facial orbit widely, malar space and mandible striate. Malar space 0.6 × as long as width of mandibular base. Mandible with two teeth, ventral tooth moderately longer than dorsal tooth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.
Mesosoma. 1.6 × longer than high. Mesoscutum densely punctate. Scuto-scutellar wide, groove smooth. Scutellum moderately convex, with very sparse punctures, without lateral carina, not pointed apically. Side of pronotum almost smooth. 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 slightly lamelliform. Propodeum completely carinate. Area basalis triangular, shortly stalked apically. Area superomedia 1.6 × longer than wide and 0.8 × as long as area petiolaris; anterior transverse carina (costula) reaching at 3/10 of its length. Area petiolaris large, 1.5 × longer than wide. Hind femur 4.6 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.5 × longer than 2 nd hind tarsomere; hind claw without visible teeth. Areolet shortly sessile frontally; vein 2m-cu slightly proximad its middle. Vein 1cu-a postfurcal by 0.2 its length. Postnervulus intercepted basad its middle. Hind wing with 4 distal hamuli.
Metasoma. 1 st tergite 3.6 × longer than wide. Postpetiolus smooth, with some sparse punctures. 2 nd tergite 1.1 × longer than wide. Thyridium comma-shaped. Paramere 1.3 × longer than hind metatarsus, slightly clubbed apically.
Color. Flagellum brownish; scape, pedicel and two basal flagellomeres ochreous. Head reddish-yellow. Palps, mandible except teeth, malar space, facial orbit and ventral half of frontal orbit cream-yellow. Stemmaticum black. Mesosoma reddish, propodeum slightly darker red. Ventral spot and hind edge of pronotum, tegula pale yellow. 1 st tergite brown, red basally, with reddish-brown spot apically. 2 nd tergite brown, with yellow triangular spot in apical 0.5. 3 rd tergite brown, with basal triangular yellow spot in basal 0.3. Following tergites brown dorsally and yellow laterally. Ovipositor sheath brownish. Fore and mid coxae and trochanters cream-yellow. Fore and mid legs otherwise yellow. Hind leg reddish; hind tibia yellowish, reddish basally and in apical 0.3. Hind tarsus ochreous. Pterostigma brownish-hyaline.
Taxonomical remark. This species belongs to the pectoralis group sensu Schwenke (1999), e. g. basal and apical tergites ± dark, mid tergites with large yellowish spots or bands. It is characterized by the longer ventral mandibular tooth, stalked area basalis, mainly reddish mesosoma and typical color pattern of 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 11-12, DOI: 10.11646/zootaxa.5245.1.1, http://zenodo.org/record/7673309