Species of Monogenoidea infecting the gill lamellae of the common silver-biddy Gerres oyena (Forsskål) and the common silver belly Gerres subfasciatus Cuvier (Perciformes: Gerreidae) in Moreton Bay, Queensland, Australia.

As part of a survey of the parasites infecting the fishes of Moreton Bay, Queensland, Australia, the gill lamellae of two species, the common silver-biddy Gerres oyena (Forsskål) and the common silver belly Gerres subfasciatus Cuvier (both Gerreidae), were found infected with monogenoids as follows: Metahaliotrema filamentosum Venkatanarasaiah, 1981 (Dactylogyridae) was redescribed from G. oyena and recorded from G. subfasciatus (both new host records); Metahaliotrema imparilis n. sp., Protogyrodactylus monacanthus n. sp., Protogyrodactylus vulgaris n. sp. (all Dactylogyridae), Gyrodactylus xynus n. sp. (Gyrodactylidae), and Polylabris gerres (Sanders, 1944) Mamaev & Parukin, 1976 (Microcotylidae) were reported from G. subfasciatus; and Protogyrodactylus scalmophorus n. sp., Protogyrodactylus ichthyocercus n. sp., and Protogyrodactylus similis n. sp. were recorded from G. oyena. The new species are described, and the finding of M. filamentosum and P. gerres from Moreton Bay represent new geographic records. Haliotrema digyroides Zhang, 2001 and Haliotrema subancistroides Zhang, 2001 are transferred to Metahaliotrema Yamaguti, 1953 as Metahaliotrema digyroides (Zhang, 2001) n. comb. and Metahaliotrema subancistroides (Zhang, 2001) n. comb., respectively.