Memoirs of the Queensland Museum | Nature  2013  58  www.qm.qld.gov.au 49 Paradiscogaster leichhardti sp. nov. (Digenea: Faustulidae) in Chaetodontoplus meredithi (Perciformes: Pomacanthidae) from Heron Island, Great Barrier Reef Pablo E. DIAZ 1 Thomas H. CRIBB 1, 2 1. School of Biological Sciences, The University of Queensland, Brisbane Qld, 4072, Australia; 2. Biodiversity Program, Queensland Museum, PO Box 3300, South Brisbane Qld 4101, Australia. Email: pablo.diazmorales@uqconnect.edu.au Citation: Diaz, P.E. & Cribb, T.H. 2013 10 10: Paradiscogaster leichhardti sp. nov. (Digenea: Faustulidae) in Chaetodontoplus meredithi (Perciformes: Pomacanthidae) from Heron Island, Great Barrier Reef. Memoirs of the Queensland Museum – Nature 58: 49–53. Brisbane. ISSN 0079-8835. Accepted: 13 August 2013. ABSTRACT Paradiscogaster leichhardti sp. nov. (Digenea: Faustulidae) is described from the intestine of Chaetodontoplus meredithi (Perciformes: Pomacanthidae) from the southern Great Barrier Reef. The new species is distinguished by its elongate, spindle-shaped body and vitellarium which forms separate groups at the level of the anterior and posterior ends of the cirrus-sac. This is the second species of Paradiscogaster reported from pomacanthid ishes.  Paradiscogaster leichhardti, Chaetodontoplus meredithi, Heron Island, Great Barrier Reef. This volume of the Memoirs of the Queensland Museum celebrates the bicentenary of the birth of the distinguished Prussian explorer and naturalist Ludwig Leichhardt, (1813 – c.1848). Leichhardt was one of several important early explorers of inland Australia and, like many of his contemporaries, his interests in natural history were very broad. However, he was exceptional in having his interests extend to the parasites found in Australian native animals. The journal of his 1844-5 expedition from Moreton Bay in south-east Queensland to Port Essington in the Northern Territory refers to a trematode from the Dawson River as follows: The water holes abounded with jew-fish and eels; of the latter we obtained a good supply, and dried two of them, which kept very well. Two species of Limnaea [sic], the one of narrow lengthened form, the other shorter and broader; a species of Paludina, and Cyclas and Unios, were frequent. The jew-fish has the same distoma in its swimming bladder, which I observed in specimens in the Severn River to the southward of Moreton Bay: on examining the intestines of this fish they were full of the shells of Limnea and Cyclas. The “jew-fish” referred to here was undoubtedly Tandanus tandanus Mitchell, the common Australian freshwater catfish. The “distoma” was almost certainly Isoparorchis hypselobagri (Billet, 1898) (Isoparorchiidae) the largest and most striking trematode yet reported from an Australian freshwater fish, growing as it does to several cm in length (Johnston 1927; Cribb 1988). The species was described from Australia as Isoparorchis tandani Johnston, 1927 but is presently known under the name I. hypselobagri. We note that Leichhardt’s keen observations on the diet of the fish would have led him to excellent work in the elucidation of trematode life cycles in another era and with different opportunities. In these circumstances it is our pleasure to celebrate his achievements