Comparative anatomy of the larvae of argid sawflies (Hymenoptera: Argidae): a phylogenetic approach

Abstract

The larval stage remains unknown for many sawflies, making it difficult to explore the phylogenetic significance of larval morphology. Here, we assemble a data set from the larval anatomy of 22 genera of Argidae and Zenargidae. We scored 85 characters for 48 terminal taxa and use a maximum parsimony approach applying equal (EW) and implied weights (IW) for phylogenetic reconstruction. We describe in detail for the first time the final larval instar of Zenarge turneri to illustrate the character systems employed. We retrieve the topology Zenarge + (Argidae s. stricto + Pergidae) in both EW and IW analyses; however, the branch support is low. We explore the phylogenetic relationships and character optimization based on the k value = 15 IW tree. Argidae s. stricto and Pergidae are recovered only under IW analyses. Within Argidae, two main clades are retrieved; these are congruent with the subfamilies Arginae and Sterictiphorinae s. Benson (1963). The genera Arge and Didymia are not retrieved as monophyletic. In general, the relationships produced by analyzing the larval morphology are consistent with those derived from adult morphology. We identify some patterns in the evolution of larval morphology of the Argidae.