Aggregata dobelli N. Sp. and Aggregata millerorum N. Sp. (Apicomplexa: Aggregatidae) from Two Species of Octopus (Mollusca: Octopodidae) from the Eastern North Pacific Ocean

ABSTRACT. Gamogony and sporogony of two new species of Aggregata (Apicomplexa: Aggregatidae) commonly were observed during histopathological examination of the digestive tracts of octopuses from the National Aquarium in Baltimore. North Pacific giant octopus, Octopus dofleini martini Pickford 1964, from British Columbia and Washington state were infected with Aggregata dobelli n. sp. Sporocysts were smooth‐surfaced, dark‐staining, subspherical to subovoid, typically 18–31 μm long by 15–27 μm wide, and contained 9–22 sporozoites, 18–23 μm long. California two‐spotted octopus, Octopus bimaculoides Pickford and McConnaughey 1949, from California were infected with Aggregata millerorum n. sp. Sporocysts were smooth‐surfaced, dark‐staining, and subspherical to subovoid, 12–20 μm long by 11–17 μm wide, and contained 8–10 sporozoites, 18–31 μm long. Both species infected the noncuticularized spiral caecum and intestine; A. millerorum n. sp. also infected the cuticularized esophagus and crop. Both parasites were present in the submucosa, muscularis, and serosa. Our observations of Aggregata infections in cuticularized regions of the gut and in the muscularis and serosa appear to be novel. Associated pathologic features included hypertrophy of invaded cells, edema, inflammation, and ulceration.