orphology and aspects of growth of a trypanosome transmitted y the marine leech Johanssonia arctica (Piscicolidae) from orthern Norway

bstract. The fish leech Johanssonia arctica (Johansson, 1898) was collected from king crabs Paralithodes camtschaticus Tilesius, 1815) in Finnmark, N Norway, and allowed to feed on experimental fish hosts in the laboratory. This leech ingested lood from laboratory-reared cod (Gadus morhua) and halibut (Hippoglossus hippoglossus). Some experimental halibut acquired rypanosome infection, with parasitaemia between ca. 500 and 60,000 trypanosomes ml. The trypanosomes were of variable ize and measured 39–90 μm (mean 57 μm) ca. 81 days post-infection. Characteristic features are cell striation, refractile ytoplasmic granules, anterior nucleus and a relatively long (ca. 6 μm, max 9 μm) distance from the posterior end to the inetoplast. Following growth, the trypanosomes became increasingly slender, with fewer striae and a nucleus position less ronounced anterior. The trypanosome is considered distinct from a type transmitted by the leech Calliobdella nodulifera (Malm, 863) in the NE Atlantic, but is regarded conspecific with a trypanosome transmitted by J. arctica in the NW Atlantic. This rypanosome has in the past been identified as Trypanosoma murmanensis Nikitin, 1927, a poorly described species. T. urmanensis cannot be recognized with certainty among the trypanosomes transmitted by C. nodulifera and J. arctica espectively. We propose that the J. arctica-transmitted species is considered T. murmanensis Nikitin, 1927 sensu stricto.