Alexeter Förster, 1869

T., Li & S. P., Sun, 2022, The genus Alexeter Förster (Hymenoptera, Ichneumonidae) in China, with descriptions of three new species, European Journal of Taxonomy 789 (81), pp. 81-103 : 82-84

Genus Alexeter Förster, 1869

Alexeter Förster, 1869 (1868) : 199.

Type-species: Mesoleptus ruficornis Gravenhorst, 1829 (= segmentarius Fabricius, 1787 ). Designated by Viereck (1914).

Zemiophron Förster, 1868: 206.

Type-species: Mesoleius laevissimus Strobl, 1903 . Designated by Perkins (1962).

Diagnosis

The diagnosis of the genus was modified from Gauld et al. (1997), Townes (1970) and Sun et al. (2019).

Clypeus separated from face, usually transversely convex medially; apical margin slightly concave or truncate centrally. Occipital carina reaching hypostomal carina distinctly above base of mandible. Notaulus nearly always long and sharp. Mesopleuron with fine to relatively large punctures. Areolet present, or 3rs-m absent ( Gauld et al. 1997). Hind wing vein 1-cu longer than cu-a. First metasomal tergite slender, latero-median carina absent, or very weak and indistinct basally. Glymma present. Second metasomal tergite with fine, or indistinct punctures. Ovipositor with a distinct dorsal subapical notch.

Key to species of Alexeter Förster, 1869 known from China

1. Mesosoma and metasoma reddish brown, or at most apical portion of metasoma dark brown. Head entirely yellowish brown, at most gena and vertex partly brownish black. Legs entirely yellowish brown to reddish brown..................................................................................................................... 2

– Mesosoma black; metasoma at least first metasomal tergite black. Fore and mid legs mostly black, or yellow to reddish brown ................................................................................................................ 3

2. Postocellar line 1.3 × as long as ocular-ocellar line. Lateromedian longitudinal carinae of propodeum more or less present; area petiolaris complete. Third metasomal tergite 1.3 × as long as posterior width. Gena, vertex and frons entirely yellowish brown........................... A. clavator ( Müller, 1776)

– Postocellar line as long as ocular-ocellar line. Lateromedian longitudinal carinae of propodeum entirely absent; area petiolaris incomplete, anterior side open. Third tergite 0.9× as long as posterior width. Gena, vertex and frons black ................................................... A. nebulator (Thunberg, 1822)

3. Metasomal tergites yellowish brown, or at least some tergites brown to reddish brown .................11

– Metasomal tergites black, at most with yellowish white or yellowish brown spots.......................... 4

4. Lateromedian longitudinal carinae of propodeum distinctly convergent anteriorly. Antenna with white ring. Face white......................................................... A. albimaculatus Sheng, Sun & Li, 2020

– Lateromedian longitudinal carinae of propodeum distinctly narrowed medially. Antenna without white ring, or if with white ring, then face black. Face black or yellow ........................................... 5

5. Median portions of lateromedian longitudinal carinae combined as single carina ( Fig. 20 ). Metasomal sternites whitish yellow; third tergite with median triangular yellowish white spot ........................... ......................................................................................................... A. flaviventris Li & Sun sp. nov.

– Median portions of lateromedian longitudinal carinae normal, distinctly separated. Metasomal sternites with lateral longitudinal black spots; all tergites black, at most posterior margins narrowly white .................................................................................................................................................. 6

6. Fore wing areolet absent. Head, masosoma and all metasomal tergites entirely black, at most clypeus and mandibular teeth with brownish black spots. All coxae, hind trochanter and femur black .......... ........................................................................................................... A. melanicus Li & Sun sp. nov.

– Fore wing areolet present. Head, masosoma and metasomal tergites with yellow or white spots. Fore and mid coxae and trochanters yellow; hind coxa red or black......................................................... 7

7. Lateromedian longitudinal carinae of propodeum absent. Ventral profile of antenna reddish brown. Face yellow........................................................................................................................................ 8

– Lateromedian longitudinal carinae of propodeum present, distinct. Ventral profile of antenna black or almost entirely black. Face black or yellowish white ................................................................. 10

8. Areolet receiving vein 2m-cu distinctly basal of or at its lower-posterior corner. Second metasomal tergite 1.2× as long as posterior width. Fore and mid coxae almost entirely black ............................ .............................................................................................................. A. niger (Gravenhorst, 1829)

– Areolet receiving vein 2m-cu at or almost at its lower-posterior corner. Second metasomal tergite at most 1.0 × as long as posterior width. Fore and mid coxae yellow ................................................... 9

9. First metasomal tergite 1.8–1.9 × as long as posterior width. Second metasomal tergite 0.8× as long as posterior width. Ovipositor sheath distinctly narrowed posteriorly. Hind coxa and femur red ...... ...................................................................................................... A. multicolor (Gravenhorst, 1829)

– First metasomal tergite 2.4× as long as posterior width ( Fig. 9 ). Second metasomal tergite 1.0× as long as posterior width ( Fig. 10 ). Ovipositor sheath symmetrical, upper and lower margins parallel ( Fig. 11 ). Hind coxa and femur black .................................................. A. flavicoxa Li & Sun sp. nov.

10. Areolet almost without petiole. Ovipositor sheath distinctly narrowed posteriorly. Hind leg entirely black........................................................................................................ A. angularis ( Uchida, 1952)

– Areolet with long petiole. Ovipositor sheath symmetrical, upper and lower margins parallel. Basal portion of hind tibia widely white. Hind tarsomeres 2–4 white ............. A. beijingensis Sheng, 2019

11. Scutellum, postscutellum, hind coxa, trochanter and femur and all tergites reddish brown. Hind tarsus pale yellow ................................................................................. A. shakojiensis Uchida, 1930

– Scutellum, postscutellum, hind coxa, trochanter and femur, metasoma, at least first metasomal tergite, almost entirely black. Hind tarsus black or dark brown...................................................... 12

12. Fore wing without areolet. Anterior-lateral portion of mesoscutum with large yellow spot. Fourth and subsequent tergites reddish brown....................................... A. zangicus Sheng, Sun & Li, 2020

– Fore wing with areolet. Mesoscutum entirely black. Fourth and subsequent tergites black ........... 13

13. Subapical portion of clypeus transversely convex, apical margin slightly concave medially. Lateromedian longitudinal carinae of propodeum distinct, narrowed medially. Face entirely black, or yellow laterally. Maxillary and labial palpi almost black.................... A. fallax ( Holmgren, 1857)

– Median portion of clypeus transversely convex, apical margin truncate. Lateromedian longitudinal carinae of propodeum indistinct, partly absent. Face yellow or with black spot. Maxillary and labial palpi brown ................................................................................... A. segmentarius (Fabricius, 1787)

Figures

Figs 15–20. Alexeter flaviventris sp. nov., holotype, ♀ (GSFGPM). 15. Head, lateral view. 16. Pronotum, anterior view. 17. Mesoscutum and scutellum, dorsal view. 18. Mesosoma, lateral view. 19. Wings. 20. Propodeum, dorsal view. Scale bars: 15–18, 20 = 0.2 mm; 19 = 0.5 mm.

Figs 9–11. Alexeter flavicoxa sp. nov., holotype, ♀ (GSFGPM). 9. First metasomal tergite, dorsal view. 10. Second metasomal tergite, dorsal view. 11. Apical portion of metasoma, lateral view. Scale bars: 9–10 = 0.2 mm; 11 = 0.1 mm.