Mesochorus (Stictopisthus) longivalvator, Riedel, 2023

Riedel, Matthias, 2023, Contribution to the taxonomy of the Southeast Asian Mesochorinae (Hymenoptera, Ichneumonidae), Zootaxa 5245 (1), pp. 1-72 : 21

Mesochorus (Stictopisthus) longivalvator nov. sp.

( Figs 3F , 10E , 23A )

Holotype. (♀) Malaysia: SE Sabah, nr Danum Valley Field C, Malaise trap 9, c 175 m, 15–19.iii.1987, C. v. Achterberg, RMNH´87 (Leiden).

Etymology. The species name refers to the long ovipositor.

Description. ♀: Body length 4.3 mm. Fore wing 3.8 mm.

Head. Flagellum with 37 flagellomeres; 1 st flagellomere 7.6 × longer than wide and 1.8 × longer than 2 nd flagellomere, 0.7 × as long as eye; 2 nd flagellomere 4.2 × longer than wide; preapical flagellomere c 2.4 × longer than wide. Occipital carina complete medially. Temple distinctly and roundly narrowed behind eye, dorsally c 0.4 × as long as eye. OED 1.6 × and OOD 0.4 × ocellar diameter. Frons almost smooth medially and with fine transverse aciculation laterally, with low rectangular elevation below anterior ocellus and with two fine and short paramedian ridges between antennal sockets. Face ( Fig. 10E ) coarsely punctate, width 1.1 × combined length of face and clypeus and 1.0 × eye length; inner eye margins parallel. Subantennal transverse carina not dipped medially. Malar space, mandible and ventral 0.4 of facial orbit striate. Malar space 1.1 × 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, covered with whitish setae. Notaulus indistinct. Mesoscutum with dense punctures, shining. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Mesopleuron with dense punctures fronto-dorsally and rather dense punctures ventrally, speculum smooth. Dorsal end of epicnemial carina separated from frontal margin of mesopleuron. Scuto-scutellar groove rather large, c 2.5 × wider than long, with c 6 longitudinal ridges. Scutellum rounded in profile, with fine sparse punctures and weak lateral carina in basal 0.4. Propodeum completely carinate. Area basalis almost rectangular, slightly longer than wide. Area superomedia 1.7 × longer than wide, smooth; anterior transverse carina (costula) reaching its middle. Area petiolaris about as long as wide. Hind femur 4.0 × longer than wide; hind metatarsus slender and long, 0.6 × as long as hind tibia and 2.8 × 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 0.6 × its length. Postnervulus intercepted basad its middle. Distal part of RA (metacarp) long, about as long as width of pterostigma. Hind wing with 4 distal hamuli. Nervellus of hind wing slightly reclivous.

Metasoma. 1 st tergite 2.5 × longer than wide. Postpetiolus longitudinally striate. 2 nd tergite about as long as wide. Thyridium comma-shaped. Ovipositor sheath ( Fig. 23A ) slender, sparsely pilose, 8.8 × longer than wide and 0.9 × as long as hind metatarsus, weakly narrowed to apex.

Color. reddish-yellow. Flagellum ochreous basally, brownish distally. Palps, mandible except teeth, malar space, ventral gena, facial orbit, scape and pedicel cream-yellow. Mesosoma yellow; mesoscutum, scutellum and propodeum reddish-yellow. 1 st tergite black, basally yellowish and reddish apically. 2 nd tergite blackish, with large triangular yellow spot in its apical 2/3. 3 rd to 5 th tergites brown dorsally, yellow laterally; following tergites entirely yellow. Ovipositor sheath brown. Fore coxae and trochanters cream-yellow, legs otherwise yellowish; hind tibia in basal 0.1 and apical 0.2 brown. Pterostigma ochreous, margins brownish.

♁ unknown.

Taxonomical remark. Belonging to the subgenus Stictopisthus , this new species is characterized by its epicnemial carina not reaching the frontal margin of mesopleuron, long and slender ovipositor sheath, stout mesosoma, and finely lateral aciculation of the frons.

Figures

FIGURE 3. Oriental Mesochorinae, habitus from lateral.A−Mesochorus harlequinus n. sp. HT, B−M. kinabaluensis n. sp. HT, C−M. lamdongensis n. sp., D−M. longimurus n. sp. HT, E−M. longistylus n. sp. HT, F−M. longivalvator 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 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.