Stethantyx mexicana Khalaim & Ruiz-Cancino

Khalaim, Andrey I. & Ruiz-Cancino, Enrique, 2013, Mexican species of the genus Stethantyx Townes (Hymenoptera, Ichneumonidae, Tersilochinae), ZooKeys 360, pp. 83-94 : 86-90

Stethantyx mexicana Khalaim & Ruiz-Cancino sp. n. Figs 10-19

Comparison.

Differs from its North and Central American congeners by the combination of brownish orange mesosoma with black mesoscutum, scutellum and propo deum (Fig. 17), and propodeum with basal keel (Fig. 18). In the key to Costa Rican species of Stethantyx ( Khalaim and Broad 2013) it runs to couplet 7 but differs in this couplet from both species, Stethantyx tenoriosa Khalaim & Broad and Stethantyx mesoscutator Khalaim & Broad, by the propodeum with basal keel (basal area in two other species), and from Stethantyx mesoscutator also by the black propodeum. The new species is morphologically similar to Stethantyx heredia as both have propodeum with basal keel but differs (besides colour pattern of mesosoma) by the somewhat longer temple and longer second metasomal tergite. Stethantyx mexicana sp. n. is a very distinct species, and despite the fact that it is described only from males, it may easily be distinguished from all known species of Stethantyx .

Description.

Male. Body length 4.8 mm. Fore wing length 3.45 mm.

Head: Roundly narrowed behind eyes in dorsal view (Fig. 10); temple almost 0.6 times as long as eye width. Mandible with upper tooth much longer than lower tooth (Fig. 12). Clypeus lenticular, flat in lateral view, about 2.5 times as broad as long, smooth, punctate on upper 0.3 (Fig. 11). Malar space 0.2 times as long as basal width of mandible (Fig. 13). Flagellum of antenna with over 28 segments (tips of all antennae absent), distinctly tapered towards apex; all flagellomeres, except the basal one, 1.3-1.4 times as long as broad (Fig. 14); flagellomeres 4 to 14 bear finger-shaped subapical structures on outer surface. Face and frons finely and densely punctate on finely granulate dull background. Vertex finely and densely punctate (punctures distinct medially and indistinct laterally) on very finely granulate, weakly shining background. Temple with very fine, mostly indistinct punctures, weakly shining. Face with weak prominence centrally. Occipital carina complete.

Mesosoma: Notaulus as small tubercle (in both paratypes) or short wrinkle (in holotype) distant from anterolateral margin of mesoscutum (Figs 10, 13). Mesoscutum very finely (sometimes indistinctly) punctate on very finely granulate, dull background. Scutellum with lateral longitudinal carinae extending from its base to posterior 0.6-0.7. Mesopleuron finely but distinctly punctate on smooth and shining background (area just above foveate groove impunctate), peripherally finely granulate. Foveate groove situated more or less in centre of mesopleuron, strongly oblique, deep and crenulate (Fig. 17). Propodeum with all carinae strong, transverse carina without adjacent wrinkles (Fig. 18). Dorsolateral area very shallowly granulate, dull, with sparse indistinct punctures. Basal keel of propodeum almost 0.4 times as long as apical area (Fig. 18). Propodeal spiracle big, adjacent to pleural carina (Fig. 17). Apical area flat, pointed anteriorly (Fig. 18).

Wings: Fore wing (Fig. 16) with first and second sections of radius angled about 130°. Intercubitus 1.5-2.0 times as long as abscissa of cubitus between intercubitus and second recurrent vein. Metacarp almost reaching apex of fore wing. Hind wing (Fig. 16) with nervellus distinctly inclivous.

Legs: Slender (Fig. 15). Hind femur slightly clavate, 4.7 times as long as broad and 0.8 times as long as tibia. Hind spurs slightly curved at apex. Tarsal claws rather long, not pectinate.

Metasoma: First tergite slender, 4.6 times as long as posteriorly broad, entirely smooth. Glymma situated somewhat behind centre of tergite, moderately large, groove between glymma and ventral part of postpetiole weak but distinct in two paratypes and absent in the holotype. Second tergite almost 2.6 times as long as anteriorly broad (Fig. 19). Thyridial depression very long, more than 5.0 times as long as broad (Fig. 19).

Coloration: Head black with lower part of face slightly reddish brown, clypeus and malar space yellow. Palpi and mandible (teeth reddish black) yellow. Scape and pedicel of antenna dark brown or brownish black; flagellum black, probably without pale band. Mesosoma brownish orange; propleuron and lower part of pronotum yellowish; mesoscutum, scutellum and propodeum dark brown or black, strongly contrasting with remaining mesosoma. Tegula fuscous. Pterostigma dark brown. Legs yellow to brownish yellow; hind leg with coxa with brown mark on extero-outer surface, femur brown to dark brown, and tibia and tarsus blackish. First tergite black. Metasoma behind first tergite predominantly dark brown (almost black dorsally), ventrally yellowish, second and following tergites with pale band posteriorly.

Female unknown.

Variability.

The three specimens are very uniform, with minor variation in structure and coloration. One paratype has the basal keel of the propodeum centrally indistinct.

Etymology.

From the type locality, Mexico.

Material examined.

Holotype male, Mexico, Chiapas, Reserva El Triunfo, Jaltenango, Red de golpeo, 15°39'22"N, 92°48'31"E, 1400 m, 21.VII.1997, coll. A. González Hernández, CIB 97-063a (UAT).

Paratypes.

Mexico, Chiapas, Palo Gordo, screen sweeping, 21.VI.1997, coll. A. González Hernández, 2 males (UAT, ZISP).

Distribution.

Mexico (Chiapas).