Studies on Three Hemiuroid Cercariae from Friday Harbor, Washington

Abstract

Life cycles have been traced for only a few species of the trematode superfamily Hemiuroidea: Halipegus occidualis by Krull (1935), H. eccentricus by Thomas (1939), H. amherstensis by Rankin (1944), Bunocotyle cingulata by Chabaud and Biguet (1955), and Lecithaster confusus by Hunninen and Cable (1943). The first intermediate hosts of Halipegus species are fresh water gastropods. The second intermediate hosts may be dragon fly nymphs, copepods, and ostracods (Macy and Demott, 1957). Adults of Halipegus occur in amphibians. Chabaud and Biguet (1955) found larval infections of Bunocotyle cingulata in brackish water mollusks. The metacercariae of this species become progenetic in copepods, but adults have been reported from fresh-water fishes, according to Yamaguti (1958). Lecithaster confusus, the only marine species whose life cycle is known, utilizes gastropods and copepods as intermediate hosts; the adult occurs in marine fishes. The development of cercariae in the gastropod host and the infection of the second intermediate host have usually been described in reports of life cycles. In addition, Dollfus (1950) described the embryology of Cercaria calliostomae in detail and Hussey (1941) followed the development of the excretory system in the cercaria of Halipegus occidualis. To date, 49 hemiuroid (cystophorous type) cercariae have been named, 27 from fresh water mollusks and 22 from marine. To the 40 species and their hosts listed by Dollfus (1950), Chabaud and Biguet (1955) added 5 more and also described the cercaria of Bunocotyle cingulata. To this list may be added Cercaria dollfusi Arvy, 1951, from Philine aperta in France, Cercaria longicerca Ito, 1953, from Semisulcospira sp. in Japan and Cercaria caribbea XXXIV Cable, 1956, from Pyrene tmercatoria in Puerto Rico. While copepods may serve as second intermediate hosts of marine hemiuroids, Lebour (1917), Linton (1927), and Myers (1955, 1956) reported larval forms in chaetognaths. Lloyd (1938) found one in a ctenophore, and Uspenskaya (1955) listed Genarches miilleri as found in an amphipod. Progenetic hemiuroids were described from a marine shrimp by Dollfus (1927) and from a fresh-water shrimp by Yeh and Wu (1955). Chabaud and Biguet (1955) have reviewed the different methods of infection of the crustacean host. Two marine hemiuroid cercariae briefly described as Cercaria A and Cercaria B by Miller (1925) were available for study during the summers of 1957 and 1958 at the Friday Harbor Laboratories of the University of Washington. Another such cercaria was found in 1958 and identified as Cercaria prenanti Arvy, 1949. Appreciation is expressed to the personnel of the laboratories for generous facilities and aid in collection, and to Dr. H. W. Manter for suggestions and criticisms. The