The Life History of Phyllodistomum staffordi Pearse, 1924 (Trematoda: Gorgoderidae Looss, 1901)

Abstract

Mother and daughter sporocysts and cystocercous cercariae develop in the fingernail clam, Musculium ryckholti. Following emergence, the cercariae are eaten by naiads of damselflies and trichopterous larvae in which they encyst. The adult Phyllodistomum staffordi develops in the urinary bladder of the brown bullhead, Ameiurus nebulosus, which acquires the parasite by eating the infected insects. The most complete account of a life history for the genus Phyllodistomum Braun, 1899 is that of Goodchild (1940, 1943) for P. solidum Rankin, 1937, a parasite in the urinary bladder of the northern dusky salamander, Desmognathus fuscus fuscus (Raf., 1820). Through experimental infections he demonstrated that mother and daughter sporocysts and cystocercous cercariae (Cercaria conica Goodchild, 1939) developed in the fingemail clam, Pisidium abditum Haldeman, 1841. Ingested cercariae encysted in odonatan naiads of the genera Ischnura, Argia, Enallagma, and Libellula. Sexual maturity was attained in the definitive host in 95 to 130 days. A very brief account of the life cycle of P. americanum Osborn, 1903 (without illustrations) was published by Crawford (1939, 1940). Definitive hosts are the mountain toad, Bufo boreas boreas Baird and Girard, 1852, and the tiger salamander, Ambystoma tigrinum (Green, 1825). Cystocercous cercariae from Pisidium spp. encysted in the wall of the esophagus of trichopteran larvae and the larvae of diving beetles and in naiads of damselflies. Excysted metacercariae, in the definitive host, first migrated to the kidneys for 2 weeks then to the urinary bladder where they developed to sexual maturity in 5 weeks. Beilfuss (1954) briefly described the life cycle of P. lohrenzi Loewen, 1935 and P. caudatum Steelman, 1938 (without illustrations). The green sunfish, Lepomis cyanellus Raf., 1819, is the definitive host for P. lohrenzi which underwent its larval development in Musculium transversum (Say, 1829). The cercaria (C. coelocerca Steelman, 1939) encysted either in the daughter sporocyst or in trichopteran larvae. The life cycle of P. caudatum is Received for publication 28 November 1966. similar except for lack of a known second intermediate host. The adult of this species developed in the black bullhead, Ameiurus melas (Raf., 1820) and the larvae in Musculium elevatum (Haldeman, 1840). The miracidium