Stethantyx oaxacana Khalaim & Ruiz-Cancino, 2020

Khalaim, Andrey I. & Ruiz-Cancino, Enrique, 2020, Contribution to the taxonomy of Mexican Tersilochinae (Hymenoptera, Ichneumonidae), with descriptions of five new species, ZooKeys 974, pp. 1-21 : 1

Stethantyx oaxacana Khalaim & Ruiz-Cancino sp. nov. Figures 27-32

Differential diagnosis.

The new species is very similar to St. covida sp. nov. but differs from this species in the shape of the ovipositor (Fig. 32 ), and shorter gena and second tergite. Stethantyx oaxacana sp. nov. also resembles St. radiata Khalaim & Sääksjärvi as both have similar shape of the ovipositor apex, but distinct in having clypeus separated from face by sharp furrow, less punctate head and mesosoma, and longer ovipositor.

Description.

Female. Body length 3.4 mm. Fore wing length 2.7 mm.

Head, in dorsal view, roundly constricted posterior to eyes (Fig. 28 ); gena ca. 0.7 × as long as eye width. Eyes glabrous. Clypeus lenticular, ca. 2.8 × as broad as long, weakly convex in lateral view, separated from face by sharp furrow; smooth, with fine scattered punctures in upper part. Mandible slender, weakly constricted in basal half; upper tooth twice longer than the lower. Malar space 1.0-1.1 × as long as basal mandibular width. Antennal flagellum (Fig. 29 ) with 16-17 flagellomeres, filiform; subbasal flagellomeres 1.5-1.8 ×, subapical flagellomeres 1.2-1.3 × as long as broad; flagellomeres 4 to 6 bearing subapical finger-shaped structures on outer surface (hardly discernible in light microscope). Face weakly convex. Face and frons finely (sometimes indistinctly) punctate on smooth or slightly scabrous background. Vertex and gena polished, without distinct punctures. Occipital carina complete, evenly arcuate in dorsal view. Hypostomal carina present, complete.

Mesoscutum and mesopleuron finely punctate on smooth background. Notaulus with strong wrinkle on anterolateral side of mesoscutum. Scutellum with lateral longitudinal carinae at basal 0.3-0.5. Epicnemial carina not reaching front margin of mesopleuron, continuing above along front margin of mesopleuron and vanishing there (Fig. 30 ). Foveate groove situated in anterior half of mesopleuron, deep, strongly oblique, almost straight, with distinct transverse wrinkles (Fig. 30 ). Propodeal spiracle adjacent to pleural carina or separated from it by less than one diameter of spiracle (Fig. 30 ). Propodeum with rectangular or slightly widened anteriorly basal area which is 2.0-4.0 × (2.0 in holotype) as long as broad and 0.4-0.8 × (0.4 in holotype) as long as apical area (Fig. 31 ). Dorsolateral area polished, with fine punctures in holotype (Fig. 31 ) and impunctate in paratypes. Apical area flat, rounded anteriorly (Fig. 31 ); apical longitudinal carinae complete and reaching transverse carina anteriorly.

Fore wing with second recurrent vein (2m-cu) postfurcal, weakly pigmented in anterior part and distinct posteriorly. First abscissa of radius (Rs+2r) straight, longer than width of pterostigma. First and second abscissae of radius (Rs+2r and Rs) meeting at slightly acute angle. Intercubitus (2rs-m) slightly thickened, approximately twice longer than abscissa of cubitus between intercubitus and second recurrent vein (abscissa of M between 2rs-m and 2m-cu). Metacarpus (R1) not reaching apex of fore wing. Second abscissa of postnervulus (Cu&2cu-a) present, thus brachial cell is closed posteriorly. Hind wing with nervellus (cu1&cu-a) weakly reclivous. Legs slender. Tarsal claws not pectinate.

First tergite 3.7 × as long as posteriorly broad, smooth, sometimes with longitudinal striae laterally before glymma and dorsally at apex of petiole; petiole rounded or slightly trapeziform in cross-section centrally; in dorsal view, postpetiole distinctly widened at base, wider than petiole and clearly separated from it; in lateral view, upper margin of tergite weakly arcuate in basal 0.6 and stronger arcuate in apical 0.4. Glymma small but distinct, situated in apical 0.55 of tergite and joining by fine groove with lower part of postpetiole. Second tergite ca. 1.25 × as long as anteriorly broad. Thyridial depression deep, ca. 1.5 × as long as broad, with posterior end rounded. Ovipositor bent upwards over its total length, with two dorsal subapical teeth and approximately three very small teeth ventrally (Fig. 32 ); sheath 2.3-2.6 × as long as first tergite (2.6 × in holotype).

Head and mesosoma predominantly brown to dark reddish brown (paratypes) or more or less entirely black (holotype); lower part of gena (near mandible) yellowish. Palpi and mandible (teeth red) yellow. Clypeus yellow, sometimes brownish in upper part. Tegula yellow or brownish yellow. Scape and pedicel of antenna yellowish brown; flagellum brownish black. Pterostigma brown. Legs brownish yellow; hind coxa sometimes darkened with brown basally; apices of tibiae and tarsi sometimes infuscate. Metasoma more or less uniformly brown or dark brown in paratypes, or extensively yellow ventrally and posteriorly in holotype (Fig. 27 ).

Male. Unknown.

Variation.

All paratypes are smaller (body length ca. 2.5 mm, fore wing length ca. 2.2 mm), paler and with weaker punctures than the holotype. Foveate groove of mesopleuron in paratypes is usually narrow and more or less straight. Shape and length of basal area of propodeum is very variable: 2.0 to 4.0 × as long as broad, and 0.4 to 0.8 × as long as apical area.

Etymology.

The species is named after the type locality, [State of] Oaxaca.

Material examined.

Holotype female (UNAM), Mexico, Oaxaca, Santiago Comaltepec, 17.58429N, 96.49398W, 2332 m, 6.VI.2009, coll. H. Clebsch & A. Zaldívar.

Paratypes. 7 females (3 in UNAM, 2 in UAT, 2 in ZISP), Mexico, Oaxaca, Santiago Comaltepec, 17.58424N, 96.49428W, 2427 m, Malaise trap, 12-20.VI.2007, coll. H. Clebsch.

Distribution.

Mexico (Oaxaca).

Figures

Figures 27 - 32. Stethantyx oaxacana sp. nov., holotype female 27 habitus, lateral view 28 head and mesoscutum, dorsal view 29 head with antennae, lateral view 30 head and mesosoma, lateral view 31 propodeum, dorsal view 32 apex of ovipositor, lateral view.