A new opecoelid trematode is reported from fishes of the Lethrinidae, Lutjanidae and Nemipteridae off Lizard Island on the northern Great Barrier Reef, Australia. The new species keys to Neolebouria Gibson, 1976 and shows strong similarity to several species of that genus, but is not consistent with the type-species, N. georgiensis Gibson, 1976, or others known from temperate/polar and/or deep-sea fishes. The new species is also phylogenetically distant from N. lanceolata (Price, 1934) Reimer, 1987, the only representative of the genus for which molecular data are available. A new genus, Trilobovarium n. g., is proposed for the new species, T. parvvatis n. sp. Eight morphologically similar species, previously recognised as belonging to Neolebouria, from shallow-water, mostly tropical/subtropical fishes, are transferred to Trilobovarium: T. diacopae (Nagaty & Abdel Aal, 1962) n. comb.; T. ira (Yamaguti, 1940) n. comb.; T. khalili (Ramadan, 1983) n. comb.; T. krusadaiense (Gupta, 1956) n. comb.; T. lineatum (Aken'Ova & Cribb, 2001) n. comb.; T. moretonense (Aken'Ova & Cribb, 2001) n. comb.; T. palauense (Machida, 2014) n. comb.; and T. truncatum (Linton, 1940) n. comb. Paramanteriella Li, Qiu & Zhang, 1988 is resurrected for five species of Neolebouria with a post-bifurcal genital pore: P. cantherini Li, Qiu & Zhang, 1988; P. capoori (Jaiswal, Upadhyay, Malhotra, Dronen & Malhotra, 2014) n. comb.; P. confusa (Overstreet, 1969) n. comb.; P. leiperi (Gupta, 1956) n. comb.; and P. pallenisca (Shipley & Hornell, 1905) n. comb. Neolebouria georgenascimentoi Bray, 2002, a species with an exceptionally long cirrus-sac, is transferred to Bentholebouria Andres, Pulis & Overstreet, 2004 as B. georgenascimentoi (Bray, 2002) n. comb., and N. maorum (Allison, 1966) Gibson 1976, an unusual species known from cephalopods, is designated a species incertae sedis. Eleven species are retained in a revised concept of Neolebouria.