Life history of Ribeiroia marini (Faust and Hoffman, 1934) comb.n. (Trematoda: Cathaemasiidae).

The life cycle of a trematode found parasitizing the snail Biomphalaria glabrata from St. Lucia, West Indies, and identified as Cercaria marini Faust and Hoffman, 1934, was completed experimentally. On the basis of adult and larval characteristics, this parasite has been named Ribeiroia marini. Cercariae encyst in goldfish. Adults develop in the proventricular wall of pigeons, canaries, and finches that are fed metacercariae, but not in ducks, mice, and hamsters. Eggs appear in host feces 7 to 9 days postinfection and hatch in approximately 9 days. Miracidia, which have 6-9-4-2 epidermal plates, penetrate snails and develop into sporocysts, which localize in the mantle veins near the kidney and in the dorsal ridge. Sporocysts produce rediae, which are located mainly in the ovotestis. Natural hosts for this parasite on St. Lucia are B. glabrata, guppies (Lebistes sp.), and little blue herons (Florida caerula). Naturally infected snails, Biomphalaria glabrata, collected in St. Lucia, West Indies, and air-shipped to San Francisco, were shedding the cercaria first described by Marin (1928) as Cercaria III. This was redescribed by Faust and Hoffman (1934) as Cercaria marini. In both instances the cercariae were from Puerto Rico. Riggin (1956), in a note on the life cycle of the Puerto Rican trematode, identified the adult as Ribeiroia ondatrae (Price, 1931). The generic position of this species is disputed. Yamaguti (1958) erected the genus Pseudopsilostoma for it, because Price (1931) did not mention esophageal diverticula in his description. Mettrick (1963) agreed, but Lumsden and Zischke (1963), finding those diverticula overlooked by Price in the type specimen, reduced Pseudopsilostoma to synonymy with Ribeiroia Travassos, 1939. The North American form is properly called R. ondatrae, but differences, particularly in the miracidium and cercaria, show that the CaribReceived for publication 25 October 1968. * This work was supported by Research Grant AI-07054 from the NIAID and by the University of California International Center for Medical Research and Training (UC ICMRT, Hooper Foundation, University of California San Francisco Medical Center) with Research Grant TW-00144 from the Office of International Research, both from the NIH, U. S. Public Health Service. t Current address: Hooper Foundation ICMRT, Institute for Medical Research, Kuala Lumpur, Malaysia. + Staff member of the Rockefeller Foundation, on assignment to the Research and Control Department, St. Lucia, West Indies. bean form is a distinct species, which must take the specific name of the cercaria, becoming R. marini (Faust and Hoffman, 1934), comb. n. MATERIALS AND METHODS Goldfish, placed for 1 or 2 nights in aquaria with shedding snails, yielded metacercariae that were fed to white mice, golden hamsters, domestic ducklings, chicks, pigeons, canaries, and three species of finches: Estrilda troglodytes (Lichtenstein), Taeniopygia castanotus (Gould), and Uroloncha striata (Brisson). All hosts, purchased from commercial breeders, were free from previous trematode infection. Pigeons and smaller birds were usually used because of ease of handling. The small birds were maintained singly or in pairs above 1 cm of water in rectangular glass aquaria 14 by 24 by 17 cm high. Water containing bird droppings and other debris was strained daily into a conical graduate, washed and sedimented 2 or 3 times, and finally placed in a petri dish for incubation at 28 C. Whenever possible, snails were exposed directly to freshly hatched swimming miracidia. When these were unavailable, exposure was made by placing the petri dish bottoms, wrapped in plastic insect screening, in aquaria with laboratory-raised snails. We used four strains of B. glabrata: an albino stock developed at the National Institutes of Health, Bethesda, Maryland; and pigmented strains from St. Lucia and from the Brazilian states of Minas Gerais and Bahia. Snails were fed only red-leaf lettuce (Lactuca sativa) and chalk and maintained in aquaria containing about 4 liters of water, aerated with an air stone or a charcoal-andglass-wool filter. All measurements are in microns.