Stethantyx durrelli Khalaim, 2017

Khalaim, Andrey I., 2017, Contribution to the study of the genus Stethantyx Townes (Hymenoptera, Ichneumonidae, Tersilochinae), with the description of a new species from Brazil, Journal of Hymenoptera Research 55, pp. 129-138 : 132-137

Stethantyx durrelli Khalaim sp. n. Figs 1-7 , 8-14 , 15-21

Comparative diagnosis.

Stethantyx durrelli sp. n. is very similar to S. grandis but differs from it by the metapleuron and dorsolateral area of propodeum densely punctate on a finely granulate background (Figs 10 , 11 , 20 ), without coarse, irregular rugae; fore wing with intercubitus 5.0 times as long as abscissa of cubitus between intercubitus and second recurrent vein (Fig. 13 ) (versus 2.0 times in S. grandis ); hind wing with nervellus strongly inclivous (Fig. 14 ) (slightly inclivous to vertical in S. grandis ); hind femur of female weakly clavate (Fig. 12 ); first metasomal segment trapeziform in cross-section and with deep glymma (Figs 15 , 16 , 21 ); and ovipositor with a sharp dorsal subapical notch (Fig. 18 ). Moreover, the new species is generally paler than S. grandis and has a somewhat longer ovipositor. These two species are the largest known Tersilochinae with body length 10.5 to 15.0 mm (the largest specimens of Barycnemis and Stethantyx have body lengths up to 10.0 mm), and can be distinguished from their congeners using a partial key to species of Stethantyx above.

Description.

Female. Body length 13.0 mm. Fore wing length about 9.2 mm.

Head rounded posterior to eyes in dorsal view (Fig. 4 ); temple 0.7 times as long as eye width. Mandible finely and densely punctate basally, upper tooth distinctly longer than lower. Clypeus broad, lenticular, 3.2 times as long as broad (Fig. 3 ), separated from face by shallow broad impression, densely and coarsely punctate in upper half, smooth and impunctate in lower half, weakly convex in lateral view. Malar space half as long as basal mandibular width. Maxillary and labial palpi short (Fig. 5 ). Flagellum of antenna short, distinctly narrowed towards apex, with 36 flagellomeres (Fig. 1 ); all flagellomeres, except basal and apical ones, distinctly transverse; flagellomeres 2 to 7-9 (weak and inconspicuous on flagellomeres 8 and 9) bearing finger-shaped subapical structures on outer surface (Fig. 2 ). Inner eye orbits very weakly convergent ventrally (Fig. 3 ). Face with rather dense and long brownish setae, centrally with blunt prominence. Face and frons densely punctate (distance between punctures mostly shorter than one puncture diameter), very finely granulate to almost smooth between punctures, dull. Vertex and temple with moderately dense punctures, smooth and weakly shining between punctures. Occipital carina complete. Hypostomal carina completely absent (Fig. 5 ).

Notaulus rather long, weakly impressed, with a strong longitudinal wrinkle and sometimes with weak adjacent wrinkles (Figs 6 , 7 ). Mesoscutum densely punctate (distance between punctures shorter than one puncture diameter), dull, finely granulate between punctures (Fig. 6 ). Scutellum with moderately dense punctures, dull, finely granulate between punctures, with lateral longitudinal carinae strong, developed in its anterior 0.7 (Fig. 9 , arrow). Epicnemial carina not joining anterior margin of mesopleuron, evanescent above (Fig. 8 ). Foveate groove of mesopleuron long, moderately broad, crenulate, extending almost entire length of mesopleuron, weak anteriorly (evanescent near epicnemial carina) and very deep and sharp centrally and posteriorly (Fig. 8 ). Mesopleuron distinctly and densely punctate, with impunctate area above foveate groove in its anterior part, smooth between punctures centrally and finely granulate peripherally (Fig. 8 ). Dorsolateral area of propodeum and metapleuron very densely punctate, dull (Figs 10 , 11 ); lower part and periphery of dorsolateral area with shallow irregular wrinkles. Basal area of propodeum slightly widened anteriorly, 1.6 times as long as anteriorly broad and 0.65 times as long as apical area; basal longitudinal carinae weak (Figs 10 , 11 ). Propodeal spiracle separated from pleural carina by 1.0-1.5 times diameter of spiracle (Fig. 8 ). Apical area anteriorly widely truncate, subrectangular (apical longitudinal carinae parallel), almost twice as long as broad (Figs 10 , 11 ), flat, very densely punctate, dull.

Fore wing (Fig. 13 ) with second recurrent vein (2m-cu) weakly postfurcal. First and second abscissae of radius (Rs+2r and Rs) angled about 120°. Intercubitus (2rs-m) not thickened, very long, about 5.0 times as long as abscissa of cubitus (M) between intercubitus and second recurrent vein. First abscissa of radius almost straight, 2.5 times as long as width of pterostigma. Metacarpus (R1) not reaching apex of fore wing. Hind wing with nervellus (cu1&cu-a) strongly inclivous (Fig. 14 ).

Hind femur slightly clavate (Fig. 12 ), 4.7 times as long as broad, and 0.75 times as long as tibia. Hind basitarsus half as long as tibia. Spurs of hind tibia distinctly curved at apex.

First metasomal segment very slender, 5.4 times as long as posteriorly broad, trapeziform in cross-section, arcuate in lateral view, smooth, with glymma situated somewhat behind its middle (Fig. 15 ). Glymma deep, joining ventral part of postpetiole by weak groove (Fig. 16 ). Second tergite 2.3 times as long as anteriorly broad (Fig. 17 ). Thyridial depression long (Fig. 17 ); thyridium slightly elongate, separated from anterior margin of second tergite by 3.5 times times maximum diameter of thyridium. Ovipositor upcurved, with a deep dorsal subapical notch; sheath 1.9 times as long as first tergite and 1.75 times as long as hind tibia.

Head black; palpi, lower half of clypeus and mandible (except black teeth) brownish yellow. Antenna with scape and pedicel dark brown, flagellum black. Mesosoma (including tegula) black. Pterostigma pale brown. Legs brownish yellow; all coxae black; trochanters brown to brownish black; fore and mid femora brownish; hind femur brown, on lower and inner sides brownish black. Metasomal tergite 1 black, following tergites brown. Wings infumate with yellow-brown.

Male. Body length 10.5-13.0 mm, fore wing length 8.4-9.5 mm. Flagellum with 38 flagellomeres (Fig. 19 ); flagellomeres 3 to 8-10 (weak and inconspicuous on flagellomeres 9 and 10) bearing finger-shaped subapical structures on outer surface. Malar space 0.4 times as long as basal mandibular width. Propodeal spiracle separated from pleural carina by 0.5-1.0 times diameter of spiracle. Basal area of propodeum 0.7-0.8 times as long as apical area (Fig. 20 ). First tergite very slender and almost straight in lateral view (Fig. 21 ); groove between glymma and ventral part of postpetiole absent or indistinct. Otherwise similar to female.

Variation.

The male from São Paulo has metapleuron almost entirely covered with fine vertical wrinkles; dorsolateral area of propodeum with punctures mostly indistinct because of numerous fine wrinkles; basal area rather indistinct (basal longitudinal carinae weak); apical area hexagonal (apical longitudinal carinae ending anteriorly far from the posterior end of basal longitudinal carinae), impunctate; and nervellus less inclivous.

Type material.

Holotype female (EMUS), Brazil, State of Rio de Janeiro, Teresópolis, 13.III.1966, coll. H. & M. Townes.

Paratypes. 1 male (FSCA), Brazil, State of São Paulo, Boracéia Biological Station, Sangre Grande, 18.XI.1976, coll. T. Rogers, 23KMPO93834. 1 male (EMUS), Brazil, State of Paraná, NE of Curitiba, Campina Grande do Sul, 16.II.1966, coll. H. & M. Townes.

Distribution.

Southern and southeast Brazil (Rio de Janeiro, São Paulo, Paraná).

Etymology.

The new species is named in honour of Gerald Durrell (1925-1995), a well-known British naturalist and author of many popular books about animals.

Figures

Figures 1 - 7. Stethantyx durrelli sp. n., female, holotype: 1 antenna, lateral view 2 base of antenna, lateral view 3 head, frontal view 4 head, dorsal view 5 head, ventro-postero-lateral view 6 mesoscutum, dorsolateral view 7 head and scutellum, dorsolateral view.

Figures 8 - 14. Stethantyx durrelli sp. n., female, holotype: 8 mesosoma, lateral view 9 mesoscutum and scutellum, lateral view 10 propodeum, dorsal view 11 propodeum, dorso-postero-lateral view 12 hind femur and tibia, lateral view 13 apex of fore wing 14 basal part of hind wing.

Figures 15 - 21. Stethantyx durrelli sp. n., female, holotype (15 - 18) and male, paratype (19 - 21): 15 first tergite, lateral view 16 glymma, lateral view 17 first and second tergites, dorsal view (the arrow points to the hind end of second tergite) 18 apex of ovipositor, lateral view 19 antenna, lateral view 20 propodeum, dorsolateral view 21 propodeum and first tergite, lateral view.