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The tapeworm Alcataenia larina (Cestoda: Cyclophyllidea: Dilepididae) is a parasite of gulls (Laridae) with a Holarctic distribution in oceanic and littoral habitats. Two subspecies Alcataenia larina pacifica and Alcataenia larina larina are recognized with the former occurring in the North Pacific basin and the latter in the North Atlantic. Alcids serve as incidental hosts for both species and infections are generally rare, usually involving few specimens. We report A. l. larina in Atlantic puffins (Fratercula arctica) collected from the Bay of Exploits, Newfoundland. The 14 strobilate and early gravid specimens were clearly distinguishable from the closely related Alcataenia cerorhincae and Alcataenia fraterculae by the smaller dimensions of the rostellar hooks and cirrus sac. Increasing numbers of gulls around seabird colonies in Newfoundland may result in more frequent contact between gulls and alcids, such as puffins (during foraging), promoting cross infections of A. l. larina.