Alcataenia fraterculae sp. n. from the horned puffin, Fratercula corniculata (Naumann), Alcataenia cerorhincae sp. n. from the rhinoceros auklet, Cerorhinca monocerata (Pallas), and Alcataenia larina pacifica ssp. n. (Cestoda: Dilepididae) in the North Pacific basin.

Abstract

Three Cestodes representing two species of the genus Alcataenia Spasskaia, 1971 and a subspecies of Alcataenia larina (Krabbe, 1869) are described. Alcataenia fraterculae sp. n. (Cestoda: Dilepididae) was found in horned puffins, Fratercula corniculata (Naumann), and other species of seabirds from localities in the western Aleutian Islands, Gulf of Alaska, Bering Sea, and Chukchi Sea. Alcataenia cerorhincae sp. n. is described from the rhinoceros auklet, Cerorhinca monocerata (Pallas) in the eastern North Pacific Ocean and western Aleutian Islands. Alcataenia larina pacifica ssp. n. is recognized from species of Laridae and other seabirds in the North Pacific Ocean, Sea of Okhotsk, Bering Sea and the region of the Arctic Ocean near Bering Strait. It is distinguished from A. larina larina (Krabbe, 1869) by a greater number of testes, a longer cirrus sac, and variation in the position of the genital ducts which may be either dorsal to or between the osmoregulatory canals. A fraterculae and A. cerorhincae are most similar to A. larina and particularly to the North Pacific form A. l. pacifica. Generally specimens of A. fraterculae can be distinguished from the other taxa by larger rostellar hooks, a longer cirrus sac, and a combination of other characters. A. fraterculae, A. cerorhincae, and A. l. pacifica however represent a complex of cryptic species in which there is extensive overlap in some morphological characters. Results of a discriminant analysis among these nominal taxa were significant and, in combination with data about other morphological characters and host and geographic distribution, clearly indicated that these represent three species in the North Pacific basin.