Aprostocetus, Westwood, 1833

Yang, Man-Miao, Lin, Yu-Che, Wu, Yaojun, Fisher, Nicole, Saimanee, Titiporn, Sangtongpraow, Benjakhun, Zhu, Chaodong, Chiu, William Chien-Hsien & Salle, John La, 2014, Two new Aprostocetus species (Hymenoptera: Eulophidae: Tetrastichinae), fortuitous parasitoids of invasive eulophid gall inducers (Tetrastichinae) on Eucalyptus and Erythrina, Zootaxa 3846 (2), pp. 261-272 : 263-264

The “ causalis group” of Aprostocetus

Aprostocetus causalis LaSalle & Wu and A. felix La Salle, Yang & Lin belong to a small group of Old World species that are associated with galls. Females are generally yellow to yellow-orange in color, and males have the gaster brown but with a distinctive white patch anteriorly on both the dorsal and ventral surfaces. This group of species is quite difficult to define because, although it does appear to be a distinct group, the only easily recognizable character to support it is the distinctive coloration of the male gaster, which is not found in any other Aprostocetus species. Unfortunately, the females are not as easy to recognize, and attempting to key them in Graham’s (1987) key to European Aprostocetus would require going 100+ couplets into the key using what are at times very difficult characters even for experts. Although members of this group have a similar biology, association with galls is not at all unusual in Aprostocetus and would not serve as a definitive character.

Other Asian species associated with galls, which appear to belong in the causalis group, have been confused with, or misidentified as, Aprostocetus gala (Walker) . This species, originally described as Tetrastichus gala , is a New World parasitoid of citrus weevils ( Schauff 1987) and thus biologically distinct from the causalis group. Aprostocetus gala females can vary in coloration ( Figs 13–15 ), and may appear similar in color to members of the causalis group. However, there are several species of Aprostocetus in which the females are yellow to yelloworange in color, and A. gala is morphologically distinct from the causalis group in the males ( Fig. 16 ), which lack the distinct white patch anteriorly on the gaster.

The Old World records in the literature for A. gala are misidentifications and need to be corrected. It is likely that these records refer to two additional species in the causalis group listed below.

Figures

FIGURES 13–16. Aprostocetus gala. 13. Female (Florida). 14 Female (Guadeloupe). 15. Female (Puerto Rico). 16. Male (British West Indies).