Marine leeches are an important component of the fish and sea turtle parasite fauna in Australia and New Zealand. However, they are very poorly known. Examination of marine leech specimens in all major Australian and New Zealand museums revealed eight genera and 16 species in Australia and six genera and 10 species in New Zealand. Two genera and three species are endemic to New Zealand; no genera, but four species are endemic to Australia.

The New Zealand fauna is highly endemic, with many species only known from their type series. Moreover, threat through habitat loss, agriculture, climate change and the introduction of alien species drive the decline of species including the little-known ones. Our study reports on the systematics and distribution of the hydrophilid genera Saphydrus and Enigmahydrus, gen. nov. and analyses whether their rare occurrence may be due to human impact. Morphology of adult and immature stages is studied in detail and the taxa are placed into a phylogenetic context.

Poecilogony (intraspecific variation in developmental mode) is very rare among marine invertebrates. We report here two candidate cases of poecilogony in the neogastropod genus Raphitoma. This would be the first documentation of poecilogony in the Neogastropoda, and the second in the whole Caenogastropoda. We discuss the implications for systematics, and the potential role of Pleistocene Mediterranean oceanographic conditions in driving the evolution of larval development in this group.

The wasp family Gasteruptiidae are an easily recognised group, whose larvae are considered predator-inquilines in the nests of bees and wasps. There has been limited molecular research on the family and as a result limited understanding of the evolutionary relationships. We present the first molecular phylogeny on Gasteruptiidae and discuss patterns of biogeography and divergence estimates. A robust phylogeny for Gasteruptiidae will provide a platform for future detailed taxonomic treatments and systematic research aimed at exploring the evolutionary relationships within the family.

Several non-biting midges have exclusively austral (Southern Hemisphere) distributions, suggesting that their distribution and diversification was due to Mesozoic breakup of the megacontinent Gondwana. We estimated a dated phylogeny for Riethia (Kieffer) (Chironomidae), supporting an underlying earth history explanation for its austral distribution. However, dates involving New Zealand, New Caledonia and South America are too young and more likely arise from transoceanic dispersal. Miocene onset of aridification likely influenced two east–west disjunctions in Australia. Diversification in this clade evidently is more complex and nuanced than naively ‘Gondwanan’.