A molecular phylogeny of the Trichogrammatidae (Hymenoptera: Chalcidoidea), with an evaluation of the utility of their male genitalia for higher level classification

Abstract A molecular phylogeny of the Trichogrammatidae (Hymenoptera: Chalcidoidea) is presented. This group of minute egg parasitoids is known from a broad range of host insects. The phylogeny produced, the first of any kind for the family, utilizes 121 taxa in fifty‐two of the eighty‐four recognized genera. Results were inferred from the ribosomal RNA regions 18S, 28S‐D2 and 28S‐D3, all aligned according to secondary structure models. Parsimony analysis was performed on both a complete and reduced dataset, in which ambiguous regions as defined by secondary structure were eliminated. The reduced dataset produced a much less resolved phylogenetic hypothesis. Only the complete dataset was utilized for Bayesian and maximum likelihood analyses. A robust‐choice Bayesian hypothesis stemmed from the concatenation of five distinct character set parameters. The results are compared with the current classification based primarily on male genitalia. Although our conclusions are partially congruent with the accepted hypothesis of trichogrammatid relationships, none of the currently adopted assemblages was recovered as monophyletic. Nevertheless, the structure of the male genitalia does correspond with relative taxon position in the molecular hypotheses. In general, the greatest genitalic simplification and fusion characterizes taxa treated as the most derived in the molecular hypotheses. Several groups are consistently recovered, but relationships between these groups and other genera vary with the analytical method. A new classification of the Trichogrammatidae is proposed. It includes one tribe, Trichogrammatini, within the subfamily Trichogrammatinae, and three tribes, Paracentrobiini, Chaetostrichini and Oligositini, within the Oligositinae. All tribes are more narrowly defined than previously and many genera are treated as incertae sedis within each subfamily. The results are interpreted in the light of morphological evidence, and the placement of genera not represented in molecular analysis is inferred by morphology alone. Host associations throughout the family are varied, although the molecular results suggest that Trichogrammatidae primitively parasitized Coleoptera, with more recent radiations onto other insect orders, such as Lepidoptera and Hemiptera.