Introduction 

A Morphological Matrix for Chalcidoidea

Chalcidoidea is one of the most megadiverse groups of insects. Ranging from the minute and morphologically bizarre male of Dicopomorpha echmepterygis (Mymaridae), the smallest known specimen of which is 0.13 mm long, to the veritable giants such as females of Leptofoenus (Pteromalidae), which exceed 20 mm, there are estimated to be more than 500,000 species in this single superfamily, of which only about 22,000 species have been described (Heraty, 2009; Noyes, 2011). Their morphological diversity is staggering (Fig. 1). Males of D. echmepterygis have lost eyes, ocelli, mouthparts, antennal flagellum, wings, tarsi except for a highly modified arolium, and virtually any other feature that place them as parasitic wasps. Galearia latreillei (Eucharitidae) has a grotesquely enlarged scutellum (Fig. 1h) similar to some Perilampidae, whereas males of Agaoninae may be reduced to turtle-like fighting machines, morphologically completely unlike their corresponding females, and females of Cameronella (Pteromalidae) with dart-shaped ovipositor sheaths are barely comparable to the distantly related aphelinid wasps, some of which attack the same host family, Eriococcidae. Convergent morphology is rampant, and enlarged femora, enlarged acropleura, reductions in the number of antennal and tarsal segments, and reductions in wing venation, wings and other features have all been proposed as being independently derived in very distantly related taxonomic groups. This extreme numerical and morphological diversity has resulted in a large number of higher taxa being described relative to other superfamilies of parasitic Hymenoptera, with 19 families and 85 subfamilies currently being recognized, and this has prevented any single individual from being able to conduct a comprehensive phylogenetic analysis based on morphology.

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