Butterfly morphology in a molecular age -- does it still matter in butterfly systematics?

We review morphological characters considered important for understanding butterfly phylogeny and evolution in the light of recent large-scale molecular phylogenies of the group. A number of the most important morphological works from the past half century are reviewed and morphological character evolution is reassessed based on the most recent phylogenetic results. In particular, higher level butterfly morphology is evaluated based on a very recent study combining an elaborate morphological dataset with a similar molecular one. Special attention is also given to the families Papilionidae, Nymphalidae and Hesperiidae which have all seen morphological and molecular efforts come together in large, combined works in recent years. In all of the examined cases the synergistic effect of combining elaborate morphological datasets with ditto molecular clearly outweigh the merits of either data type analysed on its own (even for 'genome size' molecular datasets). It is evident that morphology, far from being obsolete or arcane, still has an immensely important role to play in butterfly (and insect) phylogenetics. Not least because understanding morphology is essential for understanding and evaluating the evolutionary scenarios phylogenetic trees are supposed to illustrate.