Vol. 101, No. 2, March & April 1990 75 REDESCRIPTION OF MALES, BIOLOGICAL NOTES, AND IDENTIFICATION OF AMERICAN ACANTHOCHALCIS (HYMENOPTERA: CHALCIDIDAE)i Jeffrey A. Halstead^ ABSTRACT: Males of Acanthochalcis nigricans and /I. unispinosa are redescribed, voucher specimens designated, diagnostic characters illustrated, and a key to the American species presented. Characters to distinguish Acanthochalcis from other Nearctic Chalcididae are presented. The taxonomic and biological information on Acanthochalcis is summarized and new hosts, rearings, and floral visitations are recorded. A third species, A. gigas, is known from Madagascar. Acanthochalcis are the largest chalcidids in the Nearctic region with males ranging in length from 6 to 1 1 mm and females from 7 to 24 mm. These wasps are black with reddish brown to brown legs and smokey or yellowish wings. Females are unique among Nearctic Chalcididae in having a spear-like ovipositor which projects posteriorly a distance equal to or greater than the length of the abdomen. Acanthochalcis are uncommonly collected, though have been taken by sweeping flowering vegetation and netting individuals around host inhabiting trees and shrubs. To improve the taxonomic information on American Acanthochalcis, the males of A. nigricans Cameron and A. unispinosa Girault are rede-scribed, the species distinguished in a key, the taxonomic history re-viewed, and characters presented to distinguish this genus from other Nearctic Chalcididae. This information improves the brief original male descriptions and is needed to identify Acanthochalcis and its Amer-ican species. Male voucher specimens are deposited with their female holotype for use in future studies. The redescriptions will also be useful to delineate the presently unknown male of A. gigas Steffan (from Mada-gascar), and help establish the relationship between American and Madagascaran Acanthochalcis. Both American Acanthochalcis are parasitoids of buprestid beetle lar-vae which inhabit oak trees (Quercus spp.) (Halstead and Haines 1985); however, new information indicates buprestid hosts in saltbush (Atri-plex sp.), ocotillo (Fouguieria splendens), and Baccharis sp. Overall, the biological information on Acanthochalcis is very limited. This informa-tion is summarized and new host, rearing, and floral visitation records ^Received March 23, 1989. Accepted June 30, 1989. -California State University Fresno, Fresno, CA 93740. Present address: 1 10 W. Barstow #112. Fresno, CA 93704. ENT. NEWS 101(2): 75-80, March & April. 1990
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