IntroductionSpecies belonging to the highly diverse hemipteran infraorder Gerromorpha (the semiaquatic bugs, or water striders) are adapted to life on the water surface, and have developed a wide range of morphologies and behaviours that make them evolutionarily fascinating. The two-dimensional environment that they inhabit also renders them an extremely tractable taxon for collection and study. It is perhaps unsurprising then that the phylogeny of gerromorphs is well resolved (Andersen 1982(Andersen , 1997Damgaard et al. 2005) (Wilcox 1995) and, most recently, the evolution and maintenance of sexual conflict Rowe 1995, 2002;Arnqvist 1997;Rowe and Arnqvist 2002). However, while water striders are almost ubiquitous in their distribution worldwide, most studies exploring variation in behavioural and morphological traits or life-history parameters have focussed on the temperate species of North America and Europe; to date there are an overwhelming lack of comparable data on the tropical species of Africa and Australia (Spence and Andersen 1994; Andersen and Weir 2004a).Australia is home to 129 species of waterstriders, comprising 30 genera and six families (Andersen and Weir 2004a), and their phylogeny is well documented (Andersen and Weir 1997, 2004a, 2004b. In contrast, studies of the ecology, life-history traits or mating strategies of most of these species are sparse or, more usually, completely absent (Andersen and Weir 2004a). An important reason for addressing this regional disparity in research effort is that taxonomic evidence and limited field observations suggest that Australian species have exciting and novel evolutionary histories (Andersen and Weir 2004a). For example, a recent study of the Australian Zeus bug Phoreticovelia disparata, one of the smaller semiaquatic bugs (females ~3 mm; males 1 mm), revealed sex-role-reversed nuptial feeding, a mating strategy that is not only unique in the animal kingdom, but also challenges a core paradigm in evolutionary theory (Arnqvist et al. 2003).The genus Tenagogerris comprises three water strider species unique to Australia (T. femoratus, T. euphrosyne, T. pallidus). T. euphrosyne (Kirkaldy) is distributed along the east coast of Australia, inhabiting a variety of freshwater habitats such as lakes, billabongs and slow-flowing streams and rivers where it skates on the water surface, foraging mainly on dead and decaying insects (Andersen and Weir 2004a). In Victoria, adults are scarce between May and October (the colder winter months), suggesting that, in this region, individuals may enter reproductive diapause; in contrast, adults are abundant throughout the year in the warmer regions of north-eastern Australia (Andersen and Weir 2004a). Field-collected specimens suggest that T. euphrosyne has several morphological features typical of water striders. It is wing-dimorphic, although the frequency of the dispersing winged (macropterous) form is far lower Abstract. The hemipteran infraorder Gerromorpha (the semiaquatic bugs, or water striders) has been used exten...
