Discovery of a host fish for glochidia of Velesunio angasi (Sowerby, 1867) (Bivalvia:Unionoida:Hyriidae) from the Fortescue River, Pilbara, Western Australia

Freshwater fishes are the most common hosts of the glochidia (parasitic larvae) of freshwater mussels (Bivalvia: Unionoida: Unionoidea). Velesunio angasi (Sowerby, 1867) (Hyriidae), is the only known hyriid species recorded from the Fortescue River in the Pilbara region of Western Australia. Eleven species of fish (n = 516) were captured from pools of the Fortescue River in June 2010. Small, white, bladder-like cysts were observed on Neosilurus hyrtlii Steindachner, 1867, though not on any of the remaining 10 species examined. Light microscopy of sectioned cysts revealed that they contained glochidia that were of similar size and shape to those of V. angasi. Glochidia were found on 73.2% of 168 N. hyrtlii examined, with a mean intensity of 3.3 cysts per infested fish. Prevalence was significantly greater on smaller fish (P < 0.01); however, no relationship between size and intensity of infestation was observed. This represents the first record of glochidia infestation on fish from the Pilbara region