Mesochorus (Stictopisthus) malucutus, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 22-23

Mesochorus (Stictopisthus) malucutus nov. sp.

Figs 4B , 10G , 14F , 15B, 16E, 18E, 23C)

Holotype. (♀) Indonesia: Sula Isl. , Mangole, near Buya, Mal. trap 11, c 460 m, 12.x.–2.xi.1993, C.v. Achterberg, RMNH´93 (Leiden).

Etymology. The species name is derived from the Indonesian name of the Moluccas: Malucu.

Description. ♀: Body length 4.3 mm. Fore wing 3.2 mm.

Head. Flagellum with 32 flagellomeres; 1 st flagellomere 4.5 × longer than wide and 1.3 × longer than 2 nd flagellomere, 0.6 × as long as eye; 2 nd flagellomere 3.5 × longer than wide; preapical flagellomere c 2.5 × longer than wide. Occipital carina complete medially. Temple moderately and roundly narrowed behind eye, dorsally 0.6 × as long as eye. OED 2.0 × and OOD 0.6 × ocellar diameter. Frons with fine transverse aciculation laterally and two fine and short paramedian ridges between antennal sockets. Face ( Fig. 10G ) moderately convex, coarsely punctate, width 1.1 × combined length of face and clypeus and 1.2 × eye length; inner eye margins parallel. Subantennal transverse carina not dipped medially. Malar space, mandible and ventral 0.3 of facial orbit striate. Malar space 0.5 × as long as width of mandibular base, with strong sulcus between eye margin and clypeus. Mandible rather slender, with two equal teeth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesosoma . Moderately depressed ( Fig. 4B ), 2.2 × longer than high. Notaulus distinct in frontal third of mesoscutum. Mesoscutum ( Fig. 14F ) with rather dense to sparse punctures, shining. Mesopleuron ( Fig. 16E ) with dense coarse punctures, speculum smooth. Dorsal end of epicnemial carina reaching frontal margin of mesopleuron. Metapleuron densely punctate, juxtacoxal carina absent. Scuto-scutellar groove 3.5 × wider than long, with c 6 longitudinal ridges. Scutellum almost flat, with fine sparse punctures and weak lateral carina in basal 0.4. Propodeum ( Fig. 18E ) completely carinate. Area basalis rectangular, about square. Area superomedia 1.7 × longer than wide and 1.5 × longer than area petiolaris, with coarse transverse rugae; anterior transverse carina (costula) reaching its middle. Area petiolaris 1.2 × wider than long. Hind femur 3.1 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.7 × longer than 2 nd hind tarsomere; hind claw without visible teeth. Areolet ( Fig 15B ) pointed frontally; vein 2m-cu in its middle. Vein 1cu-a postfurcal by 1.0 × its length. Postnervulus intercepted in its middle. Pterostigma 3.0 × longer than wide. Distal part of RA (metacarp) long, about as long as width of pterostigma. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite slender, 3.1 × longer than wide. Postpetiolus with coarse longitudinal striae. 2 nd tergite 1.1 × wider than long. Thyridium comma-shaped. Ovipositor sheath ( Fig. 23C ) sparsely pilose, 5.4 × longer than wide, 0.5 × as long as hind tibia and 0.9 × as long as hind metatarsus, weakly bent upwards apically.

Color. Head reddish-yellow. Flagellum brownish. Mandible except teeth, clypeus, face, scape and pedicel yellowish. Palps, malar space, facial and frontal orbits up to anterior ocellus cream-yellow. Mesoscutum and scutellum reddish, mesoscutum with two paramedian yellowish stripes. Propodeum brown centrally, reddish-yellow laterally and apically. Pronotum, mesopleuron and metapleuron pale yellow. 1 st tergite brown, basally and apically yellow. 2 nd tergite yellow, with large V-shaped black spot basally. 3 rd tergite yellow, brown in apical 0.4. 4 th to 6 th tergites yellow, with brown basal spots. 7 th tergite entirely yellow. Ovipositor sheath brown. Fore and mid coxae, trochanters and femora cream-yellow; legs otherwise yellowish; hind tibia blackish in basal 0.2 and apical 0.2. Hind tarsus ochreous, 2 nd to 4 th tarsomeres ± brownish. Pterostigma hyaline, apical margin brownish.

♁ unknown.

Taxonomical remark. This new species differs from other known Oriental species of the subgenus Stictopisthus by a strongly depressed mesosoma, a feature that also occurs in several Palaearctic species of this group, such as Mesochorus unicinctor (Thunberg) . It is also characterized by the strongly and transversely rugose and confluent area basalis and area superomedia, and the distinctly striate postpetiolus.

Figures

FIGURE 4. Oriental Mesochorinae, habitus from lateral. A−Mesochorus malaysiacus n. sp. HT, B−M. malucutus n. sp. HT, C−M. nigripleuris n. sp., D−M. nigrofemur n. sp. HT (♀), E−M. nigrofemur n. sp. PT (♁), F−M. nigromaculatus n. sp. HT.

FIGURE 10. Oriental Mesochorinae, face from frontal. A− Mesochorus lamdongensis n. sp. HT, B−M. longimurus n. sp. HT, C−M. longistylus n. sp. HT, D−M. longistylus n.sp. (frons from dorsal), E−M. longivalvator n. sp. HT, F−M. malaysiacus n. sp. HT, G−M. malucutus n. sp. HT, J−M. nigripleuris n. sp. HT.

FIGURE 14. Oriental Mesochorinae, mesoscutum from dorsal.A−Mesochorus achterbergi n. sp. HT (♁), B−M. carinisctua n. sp. HT with carinate scutellum, C−M. flavopronotalis n. sp. HT, D−M. kinabaluensis n. sp. HT, E−M. sabahensis n. sp., F−M. malucutus n. sp. HT.

FIGURE 15. Oriental Mesochorinae, fore wings. A−Mesochorus stigmaticolor n. sp. HT, B−M. malucutus n. sp. HT.

FIGURE 16. Oriental Mesochorinae, mesopleuron from lateral. A−Orientochorus tonkinensis n. sp. HT, B−Mesochorus sulaensis n. sp. HT with juxtacoxal carina present, C−M. flavopronotalis n. sp. HT (♀), D−M. harlequinus n.sp. HT, E−M. malucutus n. sp. HT, F –M. pterostigmator n. sp. HT, G−M. tonkinesis n. sp. HT, H−M. vietnamensis n. sp. HT.

FIGURE 18. Oriental Mesochorinae, propodeum from dorsal. A− Mesochorus kinabaluensis n. sp. HT, B−M. longimurus n. sp. HT, C−M. longistylus n. sp. HT, D−M. malaysiacus n. sp. HT, E−M. malucutus n. sp. HT, F−M. nigripleuris n. sp., G−M. nigromaculatus n. sp. HT, H−M. pictiloides n. sp. HT, I−M. pterostigmator n. sp.

FIGURE 23. Oriental Mesochorinae, ovipositor sheath from lateral.A−Mesochorus longivalvator n. sp. HT, B−M. malaysiacus n. sp. HT, C−M. malucutus n. sp. HT, D−M. nigripleuris n. sp., E−M. nigrofemur n. sp. HT (♀), F−M. nigromaculatus n. sp. HT, G−M. paratenebris n. sp. HT, H−M. pictiloides n. sp. HT, I−M. pterostigmator n. sp., J−M. rufator n. sp. HT, K−M. sabahensis n. sp. HT, L−M. sapaensis n. sp. HT, M−M. semifuscus n. sp. HT, N−M. semipunctatus n. sp. HT.