Description of Neoechinorhynchus salmonis sp. n. (Acanthocephala: Neoechinorhynchidae) from Freshwater Fishes of British Columbia

Abstract

Neoechinorhynchus salmonis sp. n. differs from N. rutili in having a larger body, wider proboscis, smaller, oval eggs, in the asymmetrical outer, acanthor membrane, and the female terminal genitalia. The new species was included as N. rutili in the Van Cleave and Lynch, and Bangham and Adams collections. Neoechinorhynchus salmonis differs from both N. saginatus and N. cylindratus in the body proportions, smaller egg size, and nature of the acanthor membranes. The parasites were found in the following hosts: Oncorhynchus nerka (Walbaum) kokanee, Salmo gairdneri (Richardson) rainbow trout, Prosopium williamsoni (Girard) mountain whitefish, and Ptychocheilus oregonensis (Richardson) northern squawfish. In a survey of parasites of freshwater fishes in the Nechako Reservoir, British Columbia, a species of the genus Neoechinorhynchus was often found in large numbers among three salmonid fish species. Neoechinorhynchus rutili (Muller, 1780) had been reported from salmonid hosts from British Columbia and Washington by Van Cleave and Lynch (1950) and Bangham and Adams (1954). When comparisons of N. rutili with specimens of the present collections were made, morphological differences were found which required the naming and description of a new species, Neoechinorhynchus salmonis. MATERIALS AND METHODS A total of 1,027 fish representing eight species was collected by gill nets and minnow traps from two locations in the Nechako Reservoir, British Columbia, Canada. The locations were: Tahtsa Lake, latitude 53040', longitude 127035', and Kenney Dam area, latitude 53035', longitude 124056'. The fish were collected weekly for 10 wk from July to October 1979. An additional collection of 444 fish from Tahtsa Lake was made in September 1980. Fish were measured and weighed before standard examinations for parasites; the examination procedures used were outlined by Bullock (1978). Acanthocephalans were observed using a stereomicroscope as to their site in the intestine, state of maturity, and sex. Although most specimens were collected after being frozen, some were taken alive from freshly caught fish. Live specimens were placed in tap water until the proboscides were extended. They were then fixed in AFA, stored in 70% alcohol, stained with Semichon's carmine, cleared in xylene, and mounted in permount. More than 100 specimens with extended proboscides were mounted and studied. Drawings were made aided by a camera lucida. All measurements are in milliReceived 5 July 1982; revised 27 December 1982, 12 July 1983, 12 October 1983; accepted 26 October 1983. meters except for egg sizes which are in micrometers. The ranges are presented first followed by the means in parentheses. Measurements were made for 40 adult specimens, 20 males and 20 females from four host species.