Metacercariae of the genus Diplostomum, recovered from the eyes of the least cisco, Coregonus sardinella, were used to experimentally infect chicks of ring-billed gulls, Larus delawarensis, and herring gulls, Larus argentatus. Adults recovered from the intestine of these gulls were identified as Diplostomum baeri bucculentum based on size characteristics and the position of the anterior margin of the vitellaria to at least the level of the ventral sucker. An analysis of morphological characters from 258 gravid specimens showed a greater range in measurements than previously reported for this species. Moreover, characters such as egg numbers and size and shape components were strongly influenced by host effects. There does not appear to be the extensive geographic variability in morphology that is known for other helminth groups.
Morphological Variation Among Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus) in Eastern North America
