Microstenus rufithorax Sheng, Li & Sun, 2020

Li, Tao, Sun, Shu-Ping & Sheng, Mao-Ling, 2020, First record of the genus Microstenus Szépligeti (Hymenoptera: Ichneumonidae Cryptinae) from China, with description of one new species and a key to world species, Zootaxa 4838 (4), pp. 594-600 : 595-599

Microstenus rufithorax Sheng, Li & Sun , sp. nov.

( Figs 1–15 )

Material examined. Holotype, Female, CHINA: Shiwandashan National Forest Park, Guangxi Zhuang Autonomous Region , N 21º51´, E 107º50´, 275 m, 11 September 2019, Qing-Tang Huang (IT) . Paratypes: 8 males, same data as holotype except 9 April to 27 August 2019 ; 8 males, same data as holotype except 8 April 2020 .

Description. Holotype, female ( Fig. 1 ). Body length approximately 8.0 mm. Forewing length about 6.0 mm. Ovipositor sheath about 2.7 mm.

Head. Face ( Fig. 3 ) approximately 1.4 × as wide as long, smooth, with fine punctures and yellowish hairs; median portion slightly convex; upper margin with a small median protuberance; lateral-margin with longitudinal concave under the socket. Clypeal sulcus obvious. Clypeus approximately 2.4 × as wide as long, smooth, with sparse, fine punctures; median portion evenly convex; subapex slightly concave; apical margin truncated and evenly concave. Mandible with sparse puncture and yellowish hairs; upper tooth slightly shorter than lower tooth. Malar area ( Fig. 3 ) with fine leathery texture. Malar space approximately 0.3 × as long as basal width of mandible. Gena ( Fig. 5 ) smooth and shiny, with very sparse hairs and upper portion relatively dense hairs. Vertex ( Fig. 4 ) smooth, hind part with dense hairs. Postocellar line approximately 0.4 × as long as ocular-ocellar line. Frons smooth and shiny, with sparse yellowish brown hairs; lower portion evenly concave, dorsal tentorial pits obvious. Antenna with 21 flagellomeres, ratio of length from first to fifth flagellomeres: 1.7:1.7:1.5:1.1:1.0. Occipital carina complete. Hypostomal carina ( Fig. 6 ) absent apically.

Mesosoma. Pronotum ( Fig. 9 ) smooth, with fine punctures and yellowish hairs; apical of epomia obviously. Mesoscutum ( Fig. 8 ) evenly convex, smooth, with dense punctures and yellowish hairs; notaulus evident, convergent backwards, reaching about 0.2 the distance to posterior margin of mesoscutum. Scuto-scutellar groove smooth and shiny. Scutellum slightly convex, with sparse punctures. Postscutellum transversely convex, smooth. Mesopleuron ( Fig. 9 ) slightly convex, smooth, with dense punctures and yellowish hairs, middle portion relatively sparse; central portion oblique concave under speculum, shiny; speculum median size; episternal scrobe rounded; epicnemial carina evident, reaching about 0.3 the distance to subtegular ridge; sternaulus evident, with short ridges, reaching middle coxa. Metapleuron ( Fig. 9 ) evenly convex, smooth, with dense punctures and long yellowish hairs; juxtacoxal and submetapleural carinae complete. Wings ( Fig. 7 ) hyaline; fore wing with vein 1cu-a basad of 1/M approximately 0.5 × length of 1cu-a; areolet opened, vein 2rs-m basad of 2m-cu approximately 0.7 × length of 2rs-m; 2cu-a approximately 1.5 × as long as 2-Cu; hind wing vein 1-cu approximately 1.0 × as long as cu-a. Ratio of length of hind tarsomeres ( Fig. 10 ) from first to fifth: 13.0:5.0:2.4:1.0:3.7. Propodeum ( Fig. 11 ) evenly convex, smooth, with dense punctures and long yellowish hairs; lateromedian and lateral longitudinal carinae absent, pleural carina absent between anterior transverse carina and base of hind coxa; anterior and posterior transverse carinae strong; with a median and two sublateral longitudinal grooves between transverse carinae; spiracle oval, reaching about 0.2 the distance to anterior margin of propodeum.

Metasoma ( Fig. 12 ). Tergite I ( Fig. 13 ) approximately 4.1 × as long as basal width and 2.4 × as long as apical width, smooth, with sparse punctures at subapical area; triangular lateral tooth obvious; latero-median carina absent, dorso-lateral and ventro-lateral carinae complete; spiracle small, located at middle portion of tergite I. Tergite II ( Fig. 14 ) trapezoid, approximately 1.4 × as long as basal width and 0.9 × as long as apical width; smooth, with dense punctures and yellowish hairs, distance between punctures smaller than diameter of puncture; punctures relatively sparse at median of basal portion, anterior margin shiny; thyridium median size, oval; basal oblique groove convergent at median portion. Tergite III ( Fig. 14 ) with similar texture as tergite II, punctures relatively small. Tergite IV-VII ( Fig. 12 ) with dense punctures and yellowish hairs; tergite VII relatively shiny. Tergite VIII ( Fig. 12 ) inverted trapezoid, longitudinal convex, smooth, with dense punctures and yellowish hairs. Ovipositor sheath slender, about 0.9 × as long as hind tibia. Ovipositor ( Fig. 15 ) straight and slender, laterally compressed; lower valve with a dorsal lobe encloses upper valve, apical with 13–14 oblique ridges; apical of upper valve with wave ridges.

Coloration ( Fig. 1 ). Yellowish brown to reddish brown, except the following. Face, clypeus, mandible (teeth blackish brown), maxillary and labial palpi, spot of vertex near compound eye, frons orbit, hind tarsus (anterior of first and posterior of fifth tarsi brown) yellowish white. Flagellomeres (ventral portion of first and second flagellum yellowish brown; posterior half of fifth, dorsal portion of sixth to sixteen flagellum yellowish white), fifth tarsus of fore leg, mid tarsus, posterior margin of hind femur, posterior of hind tibia, anterior of tergites II-III, tergites VI-VII (posterior margin yellowish brown), ovipositor sheath, veins, pterostigma (anterior margin yellowish brown) brown to blackish brown. Ocellar triangle, vertex black.

Male ( Fig. 2 ). Body length 7.0–10.0 mm. Fore wing length 4.7–7.2 mm. Antenna with 25–26 flagellomeres. Tergite I (posterior half yellowish brown to reddish), anterior half of tergites II-VII, posterior half of hind tibia, anterior half of hind first tarsus, dark brown to black.

Distribution. CHINA: Guangxi.

Etymology. The name of the new species is based on the thorax being yellowish brown to reddish brown.

Remarks. This new species is similar to M. philippinus Gupta & Gupta, 1983 , but can be distinguished from the latter by the following combinations of characters: epicnemial carina reaching about 0.3 the distance to subtegular ridge; ovipositor sheath about 0.9 × as long as hind tibia; upper margin of pronotum, mesoscutum, base of propodeum yellowish brown to reddish brown; fourth and anterior half of hind tarsi yellowish white. The new species can be distinguished from all other species by the key provided above.

Figures

FIGURES 1–2. Microstenus rufithorax Sheng, Li & Sun, sp. nov. 1 holotype, habitus, lateral view 2 paratype, habitus, lateral view.

FIGURES 3–6. Microstenus rufithorax Sheng, Li & Sun, sp. nov., Holotype, but 4 of paratype. 3 head, anterior view 4 head, dorsal view 5 head, lateral view 6 head, apical of hypostomal carina (arrow), ventral view.

FIGURES 7–10. Microstenus rufithorax Sheng, Li & Sun, sp. nov., Holotype. 7 wings 8 mesoscutum and scutellum 9 mesosoma, lateral view 10 hind tarsus.

FIGURES 11–15. Microstenus rufithorax Sheng, Li & Sun, sp. nov., Holotype. 11 propodeum 12 metasoma, dorsal veiw 13 tergite I 14 tergites II-III 15 apical portion of ovipositor.