Observations on the Plerocercoid Stage of the Tapeworm Ligula in Three Species of Fish from the Lower Crooked River of Central Oregon

Abstract

Tapeworms in the genus Ligula are cosmopolitan parasites whose plerocercoid stages are found worldwide in fishes of the families Cyprinidae and Catostomidae. Examination of chiselmouth Acrocheilus alutaceus, northern pikeminnow Ptychocheilus oregonensis, and bridgelip sucker Catostomus columbianus revealed the presence of Ligula in the lower Crooked River system of central Oregon. This represents the first report of Ligula intestinalis in two of these host species: chiselmouth and bridgelip sucker. Although most hosts appeared healthy, large external lesions were noted on some bridgelip suckers in close association with a Ligula plerocercoid. The largest plerocercoid recovered was 101.5 cm relaxed length and may represent the longest plerocercoid of Ligula reported from North America.