Stethantyx radiata Khalaim & Sääksjärvi, 2015

Khalaim, Andrey I., Sääksjärvi, Ilari E. & Bordera, Santiago, 2015, Tersilochinae of Western Amazonia (Hymenoptera: Ichneumonidae). Genus Stethantyx Townes, part 2, Zootaxa 3981 (1), pp. 95-106 : 99-101

Stethantyx radiata Khalaim & Sääksjärvi , sp. nov.

( Figs 2 , 12–15 )

Description. Female. Body length 4.6 mm. Fore wing length 2.9 mm.

Head very strongly and roundly narrowed behind eyes in dorsal view ( Fig. 13 ); temple half as long as eye width. Mandible with upper tooth very long, almost 3.0× longer than lower tooth. Clypeus ( Fig. 12 ) 2.5× as broad as long, lenticular, weakly separated from face, with lower margin slightly truncated, smooth, distinctly punctate in upper 0.7, slightly convex in lateral view. Malar space 0.8–0.9× as long as basal width of mandible. Antennal flagellum narrowed towards apex, with 17–20 flagellomeres (19 flagellomeres in holotype); all flagellomeres (except basal and subapical ones) 1.5–1.7× as long as broad. Face and frons densely punctate, smooth between punctures; face with very weak prominence centrally. Vertex and temple with fine punctures, smooth between punctures. Occipital carina complete.

Notaulus with a strong wrinkle and depression posteriorly behind wrinkle ( Fig. 13 ). Mesoscutum and scutellum finely punctate on smooth background. Scutellum with lateral longitudinal carinae developed in its anterior half. Foveate groove situated in anterior 0.6 of mesopleuron, strongly oblique, deep, with strong transverse wrinkles, almost reaching prepectal carina anteriorly. Mesopleuron with dense distinct punctures, smooth between punctures, with impunctate area anteriorly (above foveate groove). Dorsolateral area of propodeum finely and sparsely punctate on smooth background. All propodeal carinae complete and strong, without adjacent wrinkles ( Fig. 14 ). Basal area of propodeum rectangular, 1.4–2.0× (1.65× in holotype) as long as broad and about 0.35× as long as apical area ( Fig. 14 ). Propodeal spiracle separated from pleural carina by 0.5–1.0× diameter of spiracle. Apical area flat, truncated anteriorly.

Fore wing with first and second abscissae of radius meeting at right angle (second abscissa curved). Intercubitus about as long as abscissa of cubitus between intercubitus and second recurrent vein, both slightly thickened. Metacarpus almost reaching apex of fore wing. Hind wing with nervellus vertical. Legs slender. Hind femur slightly clavate, 4.65× as long as broad and 0.95× as long as tibia.

First tergite slender, 4.2× as long as posteriorly broad, smooth, petiole finely striate or slightly coriaceous laterally before glymma. Glymma situated distinctly behind middle of tergite, small, joining by weak furrow to ventral part of postpetiole. Second tergite 1.55× as long as anteriorly broad. Thyridial depression long and shallow, more than 3.0× as long as broad. Ovipositor upcurved, with shallow dorsal subapical depression and distinct tooth before this depression ( Fig. 15 ); sheath 1.3–1.5× (1.5× in holotype) as long as first tergite and about 1.85× as long as hind tibia.

Head yellowish orange, interocellar area usually black; palpi and mandible (teeth dark red) yellow. Antenna with scape and pedicel yellow, flagellum fuscous. Mesosoma (including tegula) yellowish orange, holotype with median fuscous mark on mesoscutum anteriorly. Pterostigma brown. All legs entirely yellow. First metasomal tergite with petiole pale brown and postpetiole brown; following tergites predominantly yellow, tergites 2–5 dorsally brown.

Male. Flagellum with 16–19 flagellomeres. Malar space 0.5–0.6× as long as basal width of mandible. Propodeal spiracle separated from pleural carina by 1.0–2.0× diameter of spiracle. Second tergite somewhat longer. Otherwise similar to female.

Variation. One male from Ecuador has frons and vertex medially, mesoscutum, scutellum, postscutellum, propodeum and metapleuron dark reddish brown, conspicuously darker than rest of head and mesosoma.

Etymology. Named after its characteristic right-angled radial cell.

Material examined. Holotype female ( UNSM), Peru, Madre de Dios Reg., Los Amigos, 288 m, Malaise trap, 31.VII–7.VIII.2008, coll. I. Gómez.

Paratypes. Ecuador, Orellana : Onkone Gare, 0º39′25.7′′ S, 76º27′10.8′′ W, 216.3 m, canopy fogging, coll. T.L. Erwin et al.: 1 ♂ ( ZMUT) 20.VI.1994, 1 ♂ ( ZMUT) 4.X.1994, 1 ♂ ( ZMUT) 9.X.1994, 1 ♀ ( ZMUT) 21.I.2006. 1 ♂ ( ZMUT) Tiputini, 0º37′55′′ S, 76º08′39′′ W, 220–250 m, canopy fogging, 5.II.1999, coll. T.L. Erwin et al.

Distribution. Ecuador ( Orellana ), Peru (Madre de Dios).

Comparison. Differs from three other species with first and second abscissae of radius right-angled by the combination of the following characters: yellowish orange head ( Fig. 12 ), long malar space, strong notaulus, propodeum with rectangular basal area ( Fig. 14 ), second tergite about 1.5× as long as anteriorly broad, and ovipositor sheath 1.3–1.5× as long as first tergite.

Figures

FIGURES 1, 2. Stethantyx spp., ♀, holotype, habitus: 1 — S. erwini sp. nov.; 2 — S. radiata sp. nov.

FIGURES 12 – 15. Stethantyx radiata sp. nov., ♀, holotype: 12 — head, frontal; 13 — head and anterior part of mesoscutum, dorsal; 14 — propodeum, dorsal; 15 — apex of metasoma with ovipositor, lateral.