Dentilabus Heinrich, 1974

Kikuchi, Namiki & Konishi, Kazuhiko, 2018, Two new species of Dentilabus Heinrich (Hymenoptera: Ichneumonidae: Ichneumoninae) from Japan and Korea, with redefinition of the genus, Zootaxa 4524 (1), pp. 87-96 : 88-89

Genus Dentilabus Heinrich, 1974

Dentilabus Heinrich, 1974: 147 [Type species: Platylabus variegatus Wesmael, 1845 ; original designation.]; Tereshkin, 2009: 1522.

Description based on Palearctic species.

Head. Gena narrowed to occiput from behind eyes in dorsal view ( Figs. 5 , 20 ); ocellar triangle slightly or not elevated above eyes. Antennal cavity of supra-antennal area expressed and polished; internal margins of compound eyes parallel ( Figs 6 , 21 ); supra-antennal area with small and distinct tubercle between antennal sockets ( Figs 6 , 21 ); antennal sockets large, protruding anteriorly in dorsal view ( Figs 5 , 20 ); clypeus strongly convex, transverse, with straight apical margin ( Figs 6 , 21 ); anterior tentorial pits large and elongate; labrum as wide as apical margin of clypeus, trapezoid, with straight apical margin, protruding from under clypeus. Mandible slender, sharply narrowed to basal 1/3, and gradually narrowed from base to apex, with small lower tooth. Malar space considerably longer than mandible base. Occipital carina complete and meeting hypostomal carina above base of mandible, or fading out far above base of mandible; dorsomedian part of occipital carina evenly arched ( Figs 5 , 20 ). Maxillary palpus long, 2nd segment almost triangular, flat and not bulging.

Antenna. Flagella bristle-shaped, very long and slender, not flattened ( Figs 1–4 ). Male antenna with or without distinct tyloids.

Mesosoma. Collar of pronotum short, transverse furrow of pronotum not interrupted by keel ( Figs 9 , 23 ). Pronotal base without angular prominence ( Figs 10 , 24 ). Mesonotum strongly convex, notauli weak, almost not developed ( Fig. 9 ), or clearly developed in anterior 1/3 ( Fig. 23 ). Prepectal carina complete; subalar ridge not sharpened; sternaulus indistinct, not developed or shallow but reaching to middle of mesonotum; postpectal carina absent. Scutellum highly elevated, with lateral carinae ( Figs 9, 10 , 23, 24 ). Hind margin of metanotum with a triangle projection on each side of postscutellum. Propodeum usually with complete set of carinae; costula very weak or often atrophied ( Figs 9, 10 ); pleural carina rarely very indistinct ( Fig. 24 ); apex of second lateral area with distinct short apophysis almost perpendicular to surface of propodeum ( Figs 10 , 24 ). Propodeal spiracle considerably longer than wide.

Legs. Slender and long. Fore and mid tarsomeres 2–5 weakly flattened, widened to apex, and with fine short setae; spines on tarsomeres 2–4 short.

Wings. Areolet usually quadrangular, slightly petiolate above and almost symmetrical ( Fig. 13 ), or pentagonal and asymmetrical ( Fig. 14 ); single bulla on 1m-cu and 3rs-m, two bullae on 2m-cu ( Figs 13, 14 ); ramulus slightly developed or absent. Hind wing with vein cu-a ( Figs 13, 14 ).

Metasoma. Amblypygous. Petiole in profile straight, flattened, clearly wider than deep, bending at base of postpetiole ( Figs 12 , 26 ); in dorsal view clearly broadened posteriorly; dorsolateral carina and ventrolateral carina distinct, dorsomedian carina indistinct at least on basal portion of postpetiole. Gastrocoelus usually deep, quadrangular, oblique to body axis; thyridium wider than inter-thyridiae interval; inter-thyridiae area usually with impression. Lunulae large, distinct. Hypopygium with apical margin protruding and longitudinal fold in middle; ovipositor sheath with apex conical, slightly protruding behind apex of metasoma. Sternites 2–4 laterally sclerotized and middle part weakly sclerotized, sternite 5 entirely sclerotized ( Fig. 15 ).

Remarks. This genus can be easily distinguished from other genera of the tribe Platylabini by a combination of the following characteristics: gena narrowed to occiput from behind eyes in dorsal view; 2nd segment of maxillary palpus almost triangular, flat and not bulging; transverse furrow of pronotum not interrupted by keel; mesoscutum very densely punctate and not shining; apex of second lateral area of propodeum with distinct short apophysis; propodeal spiracle elongate; thyridium distinctly developed and wider than inter-thyridiae interval.

This genus has not been recorded previously from the eastern Palearctic region. We found the following two species of Dentilabus from this region.

Figures

FIGURES 5–12. Dentilabus nigripodus sp. n. 5, 6, 9, 11: holotype, 7: paratype, male from Namakusa-dani, 8: paratype, male from Fujioka, 10, 12: paratype, female from Kamuikotan. 5. head in dorsal view, 6, 7. head in frontal view, 8. scutellum to propodeum, 9. mesosoma in dorsal view, 10. mesosoma in profile, 11. metasoma, in dorsal view 12. metasoma in profile. Scale bars = 1.0 mm.

FIGURES 20–28. Dentilabus iyoensis sp. n. 20, 21, 23–26: holotype, 22, 27, 28: paratype. 20. head in dorsal view, 21, 22. head in frontal view, 23. mesosoma in dorsal view, 24. mesosoma in profile, 25. metasoma in dorsal view, 26. metasoma in profile, 27. male genitalia, 28. tyloids on male flagellum. Scale bars = 1.0 mm.

FIGURES 1–4. Habitus of Japanese Dentilabus spp. 1. D. nigripodus sp. n., holotype (female), 2. ditto, paratype (male, from Namakusa-dani), 4. D. iyoensis sp. n., holotype (female), 4. ditto, paratype (male). Scale bars = 1.0 mm.

FIGURES 13, 14. Wings of Japanese Dentilabus spp. 13. D. nigripodus sp. n., holotype, 14. D. iyoensis sp. n., holotype. Scale bars = 1.0 mm.

FIGURES 15–19. Metasomal sternites and genitalia of D. nigripodus sp. n., paratype, male from Namakusa-dani. 15. Metasomal sternites 2–7, 16. male subgenital plate (8th sternite), 17. right aedeagus in profile, 18. aedeagus in dorsal view, 19. left paramere and volsella in mesal view. Scale bars = 0.1 mm except for 15 = 1.0 mm.