Author: Daniel Tin-Hung Law

Publisher:

Published: 1975

Total Pages: 420

ISBN-13:

Seven species of fresh water fishes belonging to three different families and two species of snails from Ritner Creek, Polk County, Oregon were surveyed for adult and larval trematodes. A total of seven species of trematodes representing four families was recovered from the intestine of the fishes. Of these, at least two were under scribed new species. The trematodes were described and their taxonomy discussed. The stream snails, Oxytrema silicula and Flumenicola virens, were found to harbor at least 17 apparent species of larval trematodes. Five of these were described from the snails for the first time. A check-list of cercariae known to infect O. silicula and F. virens in the Pacific Northwest was presented. Life histories of five of the trematodes .encountered during the surveys were studied. The experimental life cycle of Apophallus donicus Skrjabin and Lindtrop, 1919 was completed. The cercaria, of the pleurolophocercous group, was found in F. virens, while the metacercaria encysted in a number of fresh water fishes. The life cycle of Plagioporus siliculus Sinitsin, 1931 was demonstrated for the first time. The cotylomicrocercous cercaria developed in sporocyst in O. silicula and penetrated crayfish, Pacifastacus lenuisculus to encyst in the abdominal muscles. The experimental definitive host used was the rainbow trout. A single adult Echinochasmus milvi Yamaguti, 1939 was recovered from a duck fed echinostome cysts found naturally in the gills of blackside dace, Rhinichthys osculus nubilus and redside shiner, Richardsoni balteatus hydrophlox. This constituted the third record of the trematode in the Pacific Northwest. The cercaria of E. milvi was believed to be Cercaria gorgonocephala Ward, 1916, which Martin (1968) redescribed from O. silicula. Two other macrocercous cercariae--one aggregating but albino while the other nonaggregating-- were also found in O. silicula, The body of these cercariae was identical to that of C. gorgonocephala. The taxonomic relation of the three cercariae was discussed. The partial life cycle of a new monorchiid trematode from the torrent sculpin, Cottus rhotheus, was presented. The natural secondary intermediate host was found to be lampreys, both brook (Lampetra richardsoni) and Pacific (L. tridentata). The first intermediate host is still unknown. The partial life cycle of another new trematode, an Echinochasmus sp., was also reported. The adult was obtained from a duck experimentally fed small cysts in the gills of blackside dace. The first intermediate host is unknown.