EN
A new genus and species, Affecauda annulata, belonging to the Gyliauchenidae Goto et Matsudaira, 1918 was found in the intestine of Naso tuberosas from Heron and Lizard Islands on the Great Barrier Reef, Queensland, Australia. This is the first record of a gyliauchenid from a species of Naso. We have placed Affecauda annulata within the Gyliauchenidae based on the structure of its digestive tract and terminal genitalia, The unusual and distinctive shape of the hindbody, which is elongate and curled, and the location of the excretory vesicle and papilla, which is distinctly anterior to the ventral sucker, distinguish this genus from other genera within the Gyliauchenidae.