Oligomerization and other evolutionary changes in the antennae of tetrastichine wasps (Hymenoptera, Eulophidae)

The following trends in oligomerization of the male and female antennae in Tetrastichinae were determined. (1) Reduction (shortening) of the basal segment of the funicle. (2) Reduction (shortening) of the middle segments of the funicle (not recorded in chalcids before). (3) Loss of homonomy by the funicle. (4) Fusion of the claval segments. (5) Reduction (shortening) of the apical claval segment. (6) Incorporation of the apical funicular segment into the clava (not recorded in eulophids before). Sex dimorphism in the antenna structure apparently results from different rates of the evolution of parts of antennae in males and females, in particular from different rates of oligomerization and appearance of novel structures in the male antennae.