margins of these mid-Columbia River reservoirs 

 (our observations). 



Results and Discussion 



Four leech species were recovered from Colum- 

 bia River fish (Table 1). About 907^ of the speci- 

 mens were Myzobdella lugubris. Two families 

 belonging to the order Rhynchobdella were rep- 

 resented, Glossiphoniidae and Piscicolidae. Mem- 

 bers of this order typically possess a small pore on 

 the anterior sucker for a mouth, from which a 

 muscular pharyngeal proboscis can be protruded, 

 and lack biting jaws or denticles. Relatively few 

 glossiphoniids are piscivorous (Klemm 1975). 

 However, the piscicolids characteristically are ec- 

 toparasites offish and feed on fish blood. The mus- 

 cular proboscis of piscicolids is effective in pene- 

 trating epidermal layers of fish wherever scales 

 are reduced or absent, although gills are favored 

 feeding sites. 



Myzobdella lugubris 



Myzobdella lugubris has not been recorded pre- 

 viously as a common ectoparasite of Columbia 

 River fish. Its distribution and host records are 

 included in previous publications that refer to the 

 genxis Illinobdella in which M. lugubris was for- 

 merly placed. 



Myzobdella lugubris and M. (syn. Illinobdella) 

 moorei (Meyer and Moore 1954) were until re- 

 cently believed to be two distinct species. The 

 former was considered characteristic of brackish 

 and marine waters, while the latter was consi- 

 dered characteristic of freshwater. The distinction 

 was primarily ecological since anatomical fea- 



TabLE 1. — Piscivorous leeches (Hirudinea) collected in this sur- 

 vey from teleost fishes in the central Columbia River, 

 Washington State. 



tures of both species were remarkably similar. 

 However, M. lugubris and M. moorei are now con- 

 sidered to be a single euryhaline species (Sawyer 

 et al. 1975). 



Further, it now appears that all members of the 

 related piscicolid genus Illinobdella are synony- 

 mous with M. lugubris. Thus species reported in 

 the literature as Illinobdella alba, I. elongata, and 

 /. richardsoni, as well as M. ( =/.) moorei, all prey- 

 ing on fish in North American waters (Meyer 

 1940, 1946b), are junior synonyms ofM. lugubris, 

 which holds taxonomic priority. Locality and host 

 records of the ubiquitous M. lugubris under these 

 synonyms are given by Hoffman (1967), Klemm 

 ( 1972a, b, 1977), and Sawyer et al. (1975). Studies 

 on M. lugubris infesting the blue crab, Callinectes 

 sapidus, and the white catfish, Ictalurus catus , in a 

 South Carolina tidal river support this synonymy 

 (Daniels and Sawyer 1975). 



Myzobdella lugubris was recovered from a wide 

 size range of adult chiselmouth, Acrocheilus 

 alutaceus, and northern squawfish, Ptychocheilus 

 oregonensis, in our collections, and less frequently 

 from adult suckers, Catostomus macrocheilus and 

 C columbianus. The associations were apparently 

 facultative. Myzobdella lugubris occurred primar- 

 ily in the oral cavity of chiselmouth (Figure 1 ) and 

 northern squawfish, where they were retained 

 during the struggle of hosts captured in overnight 

 net sets. Leeches were recorded and counted the 

 next day when fish were recovered. Many leeches 

 on the external surfaces of moribund or dead fish 

 may have detached before net recovery. Myzob- 

 della lugubris were never found in the mouth of 

 suckers but only in the axila of pelvic or pectoral 

 fins, on fin rays, or in the gill chambers. 



Myzobdella lugubris was also a fairly common 

 ectoparasite of brown bullhead,/, nebulosus, col- 

 lected by angling in backwater sloughs of the cen- 

 tral Columbia and lower Snake Rivers during the 

 summer. Infestations on bullheads usually con- 

 sisted of one or two small leeches attached to the 

 pectoral or pelvic fins. 



The incidence of M. lugubris on adult chisel- 

 mouth and northern squawfish (Table 2) shows 

 infestations only during June, July, and August 

 when C6lumbia River water temperatures ranged 

 from 13° to 21°C. The leeches were primarily sexu- 

 ally mature. Collections from the oral cavity of 

 chiselmouth in October 1975, 1977 and November 

 1977 contained numerous small, immature 

 leeches that had apparently hatched within the 

 preceding 1 or 2 mo. 



927 



