Megastylus Schiødte, 1838

Zhang, Shu-Jie, Zhou, Qing, Li, Tao & Sheng, Mao-Ling, 2022, The genus Megastylus Schiødte (Hymenoptera, Ichneumonidae, Orthocentrinae) in China with a key to the species of China and Oriental Region, Zootaxa 5091 (3), pp. 455-466 : 456

Megastylus Schiødte, 1838

Megastylus Schiødte, 1838:139 . Type-species: Megastylus cruentator Schiødte ; designated by Förster, 1871.

Diagnosis. Body usually slender. Clypeus small, strongly convex. Mandible small, strongly narrowed to apex, twisted; lower tooth usually smaller than upper tooth, or entirely lacking. Scape largely ovoid, apical truncation 50– 70° from transverse, hind edge of apical truncation membranous. Flagellum usually with long setae. Flagellomeres of male without tyloid. Eye large. Occipital carina complete. Mesoscutum strongly convex.Areolet absent. Posterior carina of propodeum usually present, located near posterior end of propodeum. Tergite 1 very long, almost straight. Ovipositor sheath about 0.5 as long as apical depth.

Key to the species of Megastylus known from China and the Oriental Region

1. Propodeum without prepropodeum. Fore wing vein 2m-cu with two bullae. (Subgenus Megastylus Schiødte, 1838 )........ 2

-. Propodeum with prepropodeum. Fore wing vein 2m-cu with one bulla. (Subgenus Dicolus Förster, 1869 )............... 3

2. Propodeum with anteromedian deep smooth concavity. Middle femur 7.5 × as long as maximum width. Frontal orbit with gray white spot........................................................... M. (M.) yindianense Sheng & Li , sp. nov.

-. Propodeum without anteromedian concavity. Middle femur at most 7.0 × as long as maximum width. Frontal orbit without gray white spot................................................................. M. (M.) cruentator Schiødte, 1838

3. Propodeum without transverse carina. Mesoscutum strongly convex. Hind femur at leat 9.5 × as long as width........... 4

-. Propodeum at least with one transverse carina. Mesoscutum relatively convex. Hind femur usually at most 9.0 × as long as width............................................................................................... 5

4. Tergite 1 4.2 × as long as posterior width. Hind femur 12.3 × as long as width. Frontal orbit, spot of mesoscutum and scutellum gray white. Propodeum and metasomal tergites fuscous................................ M. (D.) elegans Rossem, 1983

-. Tergite 1 3.8 × as long as posterior width. Hind femur 9.5 × as long as maximum width. Frontal orbit, mesoscutum and scutellum entirely black. Propodeum black. Anterior and posterior metasomal tergites black.............................................................................................. M. (D.) mentouense Sheng & Li , sp. nov.

5. Subapical portion of hind tibia strongly narrowed. Propodeum with one transverse carina. Propodeum and tergite 2 without wrinkle.................................................................... M. (D.) pectoralis ( Förster, 1871)

-. Hind tibia normal, subapical portion not narrowed. Propodeum and tergite 2 with wrinkles, or propodeum with two transverse carinae.............................................................................................. 6

6. Propodeum without wrinkle. Anterior portion of tergite 2 with indistinct irregular wrinkles. Propodeum with two transverse carinae. Face, pronotum, median rectangular spot of mesoscutum, fore and mid coxae, yellowish white...................................................................................... M. (D.) flavicornis Sheng & Li , sp. nov.

-. Propodeum and tergite 2 with distinct wrinkle. Propodeum with one transverse carina. Others not entirely as above.......7.

7. Mesopleuron, mesosternum and tergites 1–4 entirely yellow to yellowish brown. Hind coxa reddish brown.................................................................................... M. (D.) flaviventris Sheng & Sun, 2013

-. Mesopleuron and mesosternum black. At least tergites 1 or 4 black. Hind coxa black or reddish brown.................. 8

8. Notaulus vestige. Posterior carina of propodeum strong. Lower portion of mesopleuron with strong dense longitudinal wrinkles. Hind coxa with dense transverse wrinkles...................................... M. (D.) longicoxis ( Cameron, 1909)

-. Notaulus strong, reaching beyond middle. Propodeal carina very weak or indistinct. Lower portion of mesopleuron and hind coxa without wrinkles, with punctures..................................................................... 9

9. Antenna with 48 flagellomeres.Postocellar line approximately 0.7 × as long as ocular-ocellar line. Lower portion of mesopleuron with sparse fine punctures. Hind coxa, femur and tibia almost entirely reddish brown. Tergites 1–2 red..................................................................................... M. (D.) maculifacialis Sheng & Sun, 2013

-. Antenna with 42 flagellomeres.Postocellar line approximately 0.4 × as long as ocular-ocellar line. Lower portion of mesopleuron with dense punctures. Hind coxa black, femur brownish black, tibia blackish brown with narrowly buff base. Tergite 1 black. Tergite 2 blackish brown................................................ M. (D.) nigrithorax Sheng & Sun, 2013