Antistrophus Walsh, 1869

Nastasi, Louis F., Buffington, Matthew L., Davis, Charles K. & Deans, Andrew R., 2024, Key to the North American tribes and genera of herb, rose, bramble, and inquiline gall wasps (Hymenoptera, Cynipoidea, Cynipidae sensu lato), ZooKeys 1196, pp. 177-207 : 177

Antistrophus Walsh, 1869

Type species.

Antistrophus lygodesmiaepisum Walsh, 1869 (= Antistrophus pisum Ashmead, 1885)

Diagnosis.

Mesoscutum sparsely pubescent, at most with scattered setae throughout and never appearing silky. Notauli typically incomplete but complete in several species. Mesopleuron reticulate or striate-reticulate, never entirely transversely striate. Fore wing with marginal cell open, with R1 never reaching anterior wing margin, always without areolet, and with or without marginal setae. Second metasomal tergite without patch of setae.

Note.

Antistrophus contains ten described species, all of which are known from America north of Mexico ( Nastasi and Deans 2021). Antistrophus wasps are most commonly encountered in the Eastern and Midwestern United States, although two species, A. chrysothamni ( Beutenmüller) and A. microseris (McCracken & Egbert), are apparently restricted to Arizona and California respectively ( Nastasi and Deans 2021). Unpublished records indicate that the genus is far more widely distributed than currently known and is likely common throughout the United States and adjacent parts of Canada (Nastasi, pers. obs.).

Species of Antistrophus induce galls on several genera of asteraceous plants: Chrysothamnus Nutt.; Lygodesmia D.Don; Microseris D.Don; and Silphium L. Additional plant genera are known to host undescribed species. Antistrophus associated with Silphium are especially diverse and primarily comprise undescribed species; each Silphium species appears to be galled by one or more host-specific or narrowly oligophagous gall wasp species, and some Antistrophus are emerging as pests of cultivated Silphium .

Antistrophus , as currently circumscribed, is a heterogeneous assemblage. The genus contains all North American herb gall wasps that did not fit well within Aulacidea Ashmead, 1897 or Diastrophus Hartig, 1840, of which the latter is now placed in Diastrophini . Many undescribed species of this genus are known to us, and morphological and molecular data demonstrate that Antistrophus as currently defined is poorly circumscribed (unpublished data); the limits of Antistrophus will be revised by an ongoing study. Nevertheless, all described species currently placed in this genus as well as all undescribed species currently known to us correctly key to Antistrophus here.

North American species (Nastasi and Deans 2021):

1. Antistrophus bicolor Gillette, 1891

2. Antistrophus chrysothamni ( Beutenmüller, 1908)

3. Antistrophus jeanae Tooker & Hanks, 2004

4. Antistrophus laciniatus Gillette, 1891

5. Antistrophus meganae Tooker & Hanks, 2004

6. Antistrophus microseris (McCracken & Egbert, 1922)

7. Antistrophus minor Gillette, 1891

8. Antistrophus pisum Ashmead, 1885 (replacement name for A. lygodesmiaepisum Walsh as given by Nieves-Aldrey [1994] but omitted from Nastasi and Deans [2021])

9. Antistrophus rufus Gillette, 1891

10. Antistrophus silphii Gillette, 1891