A new species of Taeniacanthidae (Copepoda, Cyclopoida), Taeniacanthus kiemae sp. n., is described based on adult female and male specimens collected from the branchial cavity wall of Marilyna meraukensis (de Beaufort) and M. darwinii (Castelnau) (Teleostei, Tetraodontidae) caught in Australian waters. The new species differs from its congeners by having the following combination of characters in the adult female: 1) maxilla armed with a stout terminal process and two small elements; 2) multiple rows of spinules on the large pectinate process of the antenna; 3) an extremely long and thin maxilliped claw; 4) second exopodal segment of leg 1 with eight setae; 5) third exopodal segment of leg 3 with three spines and four setae; 6) third exopodal segment of leg 4 with three spines and two setae; and 7) each spine on the free exopodal segment of leg 5 with a subterminal flagellum. Taeniacanthus kiemae is the second copepod species reported from M. meraukensis and M. darwinii and the first taeniacanthid species reported from pufferfishes in Australia.