Mesochorus (Stictopisthus) sabahensis Riedel 2023, nov. sp.

Mesochorus (Stictopisthus) sabahensis nov. sp.

(Figs 5E, 11H, 14E, 19B, 23K)

Holotype. (♀) Malaysia: SE Sabah, nr Danum Valley Field C, c. 150 m, WONO, Mal. trap 5, 26.x. –22.xi.1987, C. v. Achterberg, RMNH´87 (Leiden).

Paratypes: (♀) with similar label (Leiden); (#f) Malaysia: SE Sabah, nr Danum Valley Field C, c 150 m, WONO, Mal. trap 5, 26.v. –20.vi.1987, C. v. Achterberg & D. Kennedy, RMNH´87 (coll. Riedel).

Etymology. The species name is derived from Sabah.

Description. ♀: Body length 3.5–3.6 mm. Fore wing 2.8–3.0 mm.

Head. Flagellum with 28–30 flagellomeres; 1 st flagellomere 5.5–5.6 × longer than wide and 1.7 × longer than 2 nd flagellomere, 0.6 × as long as eye; 2 nd flagellomere 3.4–3.6 × longer than wide; preapical flagellomere 2.0 × longer than wide. Occipital carina complete medially. Temple moderately and roundly narrowed behind eye, dorsally c 0.5 × as long as eye. OED 1.7–2.0 × and OOD 0.6–0.8 × ocellar diameter. Frons smooth, with microsculpture laterally and with fine median longitudinal ridge. Face (Fig. 11H) coarsely but partly sparsely punctate, width 1.0 × combined length of face and clypeus and 1.1 × eye length; inner eye margins slightly convergent ventrally. Subantennal transverse carina not dipped medially. Malar space, mandible and ventral 0.3 of facial orbit with fine striae. Malar space 0.9 × 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. Side of pronotum large smooth, with few very sparse punctures. Notaulus distinct in frontal 0.3 of mesoscutum. Mesoscutum (Fig. 14E) with rather dense punctures, shining. Mesopleuron densely and coarsely punctate, speculum smooth. Dorsal end of epicnemial carina reaching frontal margin of mesopleuron. Scuto-scutellar groove (Fig. 14E) rather large, c 2.5 × wider than long, with 8-10 fine longitudinal ridges. Scutellum rounded in profile, with fine sparse punctures. Propodeum (Fig. 19B) completely carinate except confluent area basalis and area superomedia. Area superomedia 1.7 × longer than wide and 1.2 × longer than area petiolaris, with some transverse rugae; anterior transverse carina (costula) reaching its middle. Area petiolaris 1.0 × as long as wide. Hind femur 3.3–3.6 × longer than wide; hind metatarsus 0.5 × as long as hind tibia and 2.7 × longer than 2 nd hind tarsomere; hind claw with c 3 basal tooth, distal teeth long. Areolet pointed frontally; vein 2mcu slightly proximad or in its middle. Vein 1cu-a postfurcal by 1.0–1.3 × its length. Postnervulus intercepted in or distad its middle. Pterostigma 2.9–3.3 × longer than wide. Hind wing with 4 distal hamuli. Nervellus of hind wing vertical.

Metasoma. 1 st tergite 2.6–2.8 × longer than wide. Postpetiolus with longitudinal rugae. 2 nd tergite 1.1 × wider than long. Thyridium comma-shaped. Ovipositor sheath (Fig. 23K) sparsely pilose, 6.8 × longer than wide, 0.5 × as long as hind tibia and 1.0 × as long as hind metatarsus, moderately bent upwards apically.

Color. Body mainly reddish. Flagellum ochreous basally, brownish distally. Palps, mandible except teeth, malar space, and wide facial orbit cream-yellow. 1 st tergite brownish, basally yellowish. 2 nd tergite yellow, with brown triangular anterolateral spots. 3 rd tergite apically and 4 th tergite basally with ± extended brown spots. Ovipositor sheath brown. Fore and mid coxae and trochanters cream-yellow, legs otherwise reddish-yellow; hind tibia not or slightly infuscate apically. Pterostigma yellowish-hyaline.

♁. Male unknown.

Taxonomical remark. Within the subgenus Stictopisthus, this new species is characterized by a somewhat reduced punctuation of face, very coarse punctuation of meso- and metapleuron, and confluent area basalis and area superomedia with some fine transverse rugae.