Two new digenetic trematodes from Australian freshwater fishes with notes on previously described species

Austrohalipegus anguillicola gen. et sp. nov. is described from the stomach of Anguilla reinhardtii Steindachner. Austrohalipegus is distinguished from other derogenid genera by the absence of filaments on its eggs, by the presence of blindly ending caeca, by having the ventral sucker in the middle of the body, by having the sinus-sac enclose only the hermaphroditic duct, and by the uterus which does not extend posterior to the vitellarium. Austrohalipegus anguillicola is distinctive in having a large temporary sinus-organ formed by a completely eversible hermaphroditic duct. Isoparorchis hypselobagri (Billet) is recorded as juveniles of 1-3 mm in length from the coelom and as larger juveniles and adults from the swim bladder of Tandanus tandanus Mitchell. The miracidium is typically hemiuroid and has a crown of apical spines and cilia in lateral bunches. Experimental infections in which the prosobranch snails Posticobia brazieri and Melanoides tuberculatus were fed embryonated eggs produced infections of mother sporocysts. It is postulated that the life-cycle includes an obligate period of development in the coelom of the definitive host for the Australian form of the species. Stegodexamene watsoni sp. nov. is described from the intestine of Maccullochella peek (Mitchell). It is distinguished from the two other species of this genus by its considerably larger cirrus pouch and its more extensive vitellaria. Burnellus trichofurcatus (Johnston and Angel) is recorded from new hosts, Arius graeffei Kner and Steindachner and Neosilurus ater (Perugia). Aspects of its biology are discussed. Pretestis australianus Angel and Manter is recorded from a new host, Scortum hilli Castelnau, extending the known range of this species