Review of papers on the male genitalia of Diptera by D.M. Wood and associates

Abstract

Three papers by D.M. Wood and associates (Wood 1991, Sinclair et al. 1994, Cumming et al. 1995) on homology and phylogenetic implications of the male genitalia in Diptera are discussed. These papers treat basic morphological questions important for interpreting the evolution of this order and contain some valid new information, but also some errors of observation and a great deal of misleading argumentation. Two of the authors’ basic concepts of morphological transformation in Brachycera are contested: first, that the evolution of the phallic structures proceeds from a highly complex ancestral form (exemplified by Tabanomorpha) to simpler derivatives by means of fusion processes; and secondly, that a clasping mechanism of epandrial origin has replaced the usual gonopodal mechanism in Eremoneura. These problematic basic concepts are supported by a series of auxiliary hypotheses which are difficult or impossible to reconcile with the empirical evidence.