A cladistic analysis of Diopsidae (Diptera) based on morphological and DNA sequence data

The results of a cladistic analysis based on a combined character matrix consisting of the morphological data set of Meier & Hilger (2000) and the molecular data set of Baker & al. (2001) is presented. The data set is subjected to an extensive sensitivity analysis and equal character weighting is found to perform best according to character incongruence and tree support. The sensitivity analysis also reveals a remarkable stability of the preferred tree with 25 of the 36 tree nodes supported under 16 different analysis conditions. Cyrtodiopsis is synonymized with Teleopsis and Shillito's (1971) synonymization of Trichodiopsis and Chaetodiopsis with Diasemopsis is confirmed. Morphological and DNA sequence data agree on all major clades and conflict is restricted to the placement of two species within their respective genera. Only in one case can the conflict be confidently resolved. Partitioned Bremer Support values reveal that 90% of the tree support is generated by the DNA sequence characters, although the average morphological character contributes twice the support of an average molecular character. The evolution of eye-stalk morphology and of a meiotic drive chromosome system in Teleopsis is briefly discussed in the light of the phylogenetic tree.