Tersilochinae (Hymenoptera: Ichneumonidae) of Costa Rica, part 2. Genera Megalochus gen. nov. and Stethantyx Townes Author Khalaim, Andrey I. Author Broad, Gavin R. text Zootaxa 2013 3693 2 221 266 journal article 10.11646/zootaxa.3693.2.8 36ea2224-55a8-4117-aba3-bfd3178f9b58 1175-5326 249392 72B60375-3DF1-4EB1-B15E-587FDB6206BF Stethantyx pseudoosa Khalaim et Broad , sp. nov. Comparison. Very similar to S. osa sp. nov. but differs by the slenderer and more or less filiform flagellum; the notaulus represented as by a weak tubercle (usually as a wrinkle in S. osa ); shorter lateral longitudinal carinae of the scutellum; mesopleuron with narrower foveate groove which does not reach its anterior margin; and smaller basal area of the propodeum. Description. Female . Body length about 5.4 mm . Fore wing length 3.7 mm . Head rounded and very strongly tapered behind eyes in dorsal view; temple 0.43× as long as eye width. Mandible slender, upper tooth much longer than lower tooth. Clypeus broad, about 2.7× as broad as high, lenticular, slightly convex or flat in lateral view, smooth and impunctate on lower half, finely and densely punctate on upper 0.4–0.5. Malar space 0.4× as long as basal width of mandible. Flagellum of antenna almost filiform, with 23–26 flagellomeres (23 flagellomeres in holotype ), all flagellomeres distinctly elongate, subbasal and mid flagellomeres 1.5–1.7× as long as broad, subapical flagellomeres weakly elongate to slightly transverse. Inner eye orbits very weakly convergent ventrally. Face with weak central prominence. Face, frons and vertex finely granulate, dull, finely and densely punctate. Temple finely and shallowly granulate, with fine and shallow punctures. Notaulus as small inconspicuous tubercle distant from anterolateral margin of mesoscutum. Mesoscutum finely granulate, dull, finely and densely punctate. Scutellum with lateral longitudinal carinae extending from its base to about midlength. Foveate groove of mesopleuron situated in anterior 0.6–0.7 of mesopleuron, strongly oblique, not especially deep and rather narrow, with transverse wrinkles, clearly separated from anterior margin of mesopleuron. Mesopleuron finely and shallowly granulate (almost smooth centrally), finely punctate. Propodeum finely granulate, dorsolateral area very finely (sometimes indistinctly) punctate, without wrinkles adjacent to carinae. Basal area of propodeum rectangular, not widened anteriorly, 1.8–2.2× (2.2× in holotype ) as long as broad, 0.4–0.5× as long as apical area, and about 0.16× as broad as propodeum (measured between propodeal spiracles in dorsal view). Propodeal spiracle separated from pleural carina by 0.5–1.5× diameter of spiracle. Apical area flat, anteriorly truncate or rounded. Fore wing with veins Rs +2 r and Rs angled 105–110°. Vein 2 rs-m slightly longer to slightly shorter than abscissa of M between 2 rs-m and 2 m-cu . Hind wing with cu 1& cu-a more or less vertical. Hind femur 5.2× as long as broad, and 0.9× as long as tibia. First tergite slender, 4.4× as long as posteriorly broad, smooth, petiole laterally striate. Glymma situated near or slightly behind middle of tergite 1, joining by very weak (sometimes indistinct) furrow to ventral part of postpetiole. Second tergite 2.4× as long as anteriorly broad. Thyridial depression more than 5.0× as long as broad. Ovipositor weakly upcurved, with shallow dorsal subapical depression; sheath 1.6× as long as first tergite and hind tibia. Head black; clypeus brownish yellow; palpi and mandible (teeth black) yellowish. Antenna with scape and pedicel dark brown, flagellum black. Mesosoma brownish orange; propleuron and anterior margin of pronotum somewhat paler; tegula reddish brown, more or less infuscate. Legs brownish yellow, hind femur slightly brownish, hind tibia and tarsus weakly to rather strongly infuscate. Pterostigma dark brown. Tergite 1 of metasoma brownish black. Metasoma behind tergite 1 yellow ventrally to dark brown dorsally, tergites 2+ dorsally with posterior pale band. Male . Unknown. Variation. A rather uniform species with minor variation. The ovipositor sheath varies from 1.4 to 1.6× as long as the first tergite. Etymology. Named after its similarity to S. osa sp. nov. Material examined. Holotype female (INBio), Guanacaste Prov., National Park Volcán Tenorio, volcano Tenorio, 1650 m , VIII–X.2003 , coll. J.A. Azofeifa. Paratypes . Alajuela Prov.: 2 Ƥ (ZISP) National Park Volcán Tenorio, N of volcano Tenorio, Guatuso, 1500– 1600 m , V–VII.2005 , coll. J.A. Azofeifa. Guanacaste Prov.: 1 Ƥ (INBio) same data as holotype . 2 Ƥ (INBio, BMNH) same data, but X–XI.2003 . 1 Ƥ (INBio) Guanacaste National Park, 9 km S of Santa Cecilia , Estación Pitilla, 700 m , X.1993 . Distribution. Costa Rica ( Alajuela , Guanacaste).