On the morphology and life-history of Sterincotrema pagelli (Van Beneden, 1871) Odhner, 1911 and Fellodistomum fellis (Olsson, 1868) Nicoll, 1909 [Syn. S. Ovacutum (Lebour, 1908) Yamaguti, 1953] (Trematoda, Fellodistomidae)

Abstract

The cercaria of Steringotrema pagelli (Van Beneden, 1871) Odhner, 1911 develops in sporocysts in the bivalve Nucula nitidosa Winckworth and N. nucleus (L.). The cercaria has two long contractile tail furcae. The cercaria is swollowed by the final host, lemon sole Microstomus kitt (Walbaum) and dab Limanda limanda (L.).

The life-cycle of S. ouacutum (Lebour, 1908) Yamaguti, 1953 is identical to that of Fellodistomum (ellis (Olsson, 1868) Nicoll, 1909 worked out in the Barents Sea. The furcocercous cercaria emerges from N. tenuis (Mont.) and is eaten by the brittle stars Ophiura albida Forbes, O. sarsi Lkt. and Amphiura chiajei Forbes. Catfish Anarhichas lupus L., long rough dab Hippoglossoides platessoides (Fabr.) and plaice Pleuronectes platessa L. are infested by eating the brittle stars. S. ovacutum is thus a synonym of F. fellis.

The cercariae of S. pagelli and F. fellis are redescribed. The developmental stages of both species are described, based on stereoscan electron microscope observations.

The life-cycle of fellodistomid trematodes are separated into four groups according to the first host and the morphology of the cercariae.