Helminths of Northwest Mammals. Part III. The Description of Euryhelmis pacificus n. sp., and Notes on Its Life Cycle

Abstract

During the spring and summer of 1951, one of the authors (C.M.S.) and Kenneth A. Neiland had the opportunity to make a preliminary survey of the helminths of some Oregon mammals. A trematode of unusual interest was collected from the mink, Mustela vision Schreber, the muskrat, Ondatra zibethica (Linnaeus), and the water shrew, Sorex bendirii palmeri taken near Portland, Oregon. This fluke had the general anatomy and egg-size characteristic of Euryhelmis squamula (Rudolphi 1819) and occurred with this species in the mink and the shrew, but it differed from it in shape. At first the worms were considered to be immature specimens of E. squamula but further study has shown that its life cycle involves a salamander rather than a frog. Because of these and other differences this fluke is considered a distinct species for which the specific name E. pacificus is proposed. Certain peculiarities of this species also require emendation of the genus. All of the material from the mink, the muskrat, and the shrew was fixed in formalin-alcohol-acetic acid solution, stained with Semichon's acetocarmine with a counterstain of fast green, cleared in either xylene or terpineol, and mounted in Clarite. The experimentally reared material was handled as above or was fixed with either corrosive-acetic acid solution or Bouin's fluid and stained with Ehrlich's