Neocalceostomoides brisbanensis sp. nov. from the gill arches, gill rakers and buccal lining of the blue catfish, Arius graeffei, is described. It is distinguished from the type species Neocalceostomoides arii (Unnithan, 1964) by the presence of a convoluted vas deferens with a blind-ending diverticulum; two lobes inside the vagina, each with ornamentation comprising rows of conical studs; two seminal receptacles and a post-testicular connection between the gut caeca. There is a closer resemblance to Neocalceostomoides spinivaginalis Lim, 1995, which also has vaginal lobes with ornamentations, but in N. spinivaginalis these ornamentations are elongated and spine-like and the penis tube and ‘gubernaculum’ are significantly longer. Neocalceostomoides brisbanensis was found on A. graeffei caught in Moreton Bay (sea water), Queensland, but not on catfish caught in the Brisbane River (fresh water). Some comments are made on the evolution and relationships of calceostomatines.