The saws of sawflies: exploring the morphology of the ovipositor in Tenthredinoidea (Insecta: Hymenoptera), with emphasis on Nematinae

The variation in ovipositor sculpture and additional features of the ovipositor apparatus in Tenthredinoidea is explored. Two outgroups and 85 species of tenthredinoids were examined, the emphasis of the taxon sampling being on Nematinae. Twenty-four morphological characters where scored and the data set was analysed under different weighting conditions. The topologies derived from analysing the character set in TNT are poorly resolved and highly unstable when analytical settings are changed. Only a few clades, the Tenthredinoidea s. str., the Diprionidae, the Cimbicidae and the Argidae + Pergidae are consistently retrieved. The functional implications of the variation in ovipositor morphology within Tenthredinidae is discussed in relation to the qualities of the host plant, e.g. the hardness and the depth of penetration in plant tissue.