Characteristics of sperm ultrastructure in the gall midges Porricondylinae (Insecta, Diptera, Cecidomyiidae) with phylogenetic considerations on the subfamily.

Sperm ultrastructure was studied in ten genera of the Porricondylinae (Cecidomyiidae). Sperm structure is remarkably simplified by the absence of the acrosome and the accessory tubules, as happens in all the cecidomyiid flies. All genera of the Porricondylinae show a peculiar 9+3 axonemal model except Diallactes, which retains the plesiomorphic condition of a 9+2 axoneme, and Winnertzia, which appears to have secondarily acquired a 9+0 model. A cladistic analysis of relevant sperm characters (based on the axonemal model, the number of mitochondrial derivatives and the size and structure of the centriolar adjunct) was performed to infer phylogenetic relationships among six tribes of the Porricondylinae. In this cladogram, the Porricondylini are the sister group to the Asynaptini, Heteropezini and Winnertzini and these four taxa form the sister group to the Dicerurini. The tribe Diallactini are regarded as the group with the most plesiomorphic characters within the family