title: Ichthyobodo salmonis sp. n. (Ichthyobodonidae, Kinetoplastida), an euryhaline ectoparasite infecting Atlantic salmon (Salmo salar L.).
abstract: Phylogenetic analyses of SSU rDNA sequences have previously revealed the existence of 2 Ichthyobodo species able to infect Atlantic salmon (Salmo salar L.). Ichthyobodo necator sensu stricto (s.s.) is assumed to be a freshwater parasite, while a genetically distinct but undescribed species, Ichthyobodo sp. II sensu Todal et al. (2004) have been detected on Atlantic salmon in both fresh- and seawater. In the present study a morphological description of Ichthyobodo sp. II from the gills of salmon reared in fresh-, brackish- and seawater is presented, using both light- and electron microscopy. Comparative morphometry show that Ichthyobodo sp. II from both freshwater and seawater displays a different cell shape, and is significantly smaller than I. necator s.s. Also, ultrastructural characteristics distinguish these two species, notably differences in the attachment region and the presence of spine-like surface projections in Ichthyobodo sp. II. Based on both unique SSU rDNA sequences and morphological characteristics, we conclude that Ichthyobodo sp. II. represents a novel species for which we propose the name Ichthyobodo salmonis sp. n.
authors.affiliation: Uni Research, Uni Environment, P.O. Box 7810, 5020 Bergen, Norway. trond.isaksen@uni.no
authors.forename: Trond E
authors.initials: TE
authors.lastname: Isaksen
authors.forename: Egil
authors.initials: E
authors.lastname: Karlsbakk
authors.forename: Kuninori
authors.initials: K
authors.lastname: Watanabe
authors.forename: Are
authors.initials: A
authors.lastname: Nylund
mesh_terms: D000818:Animals; D048430:Cell Shape; D048429:Cell Size; D004275:DNA, Ribosomal / Q000302:isolation & purification; D056986:Euglenozoa Infections / Q000469:parasitology* / Q000473:pathology; D005393:Fish Diseases / Q000469:parasitology* / Q000473:pathology; D005618:Fresh Water; D005880:Gills / Q000469:parasitology*; D006790:Host-Parasite Interactions; D016830:Kinetoplastida / Q000145:classification / Q000166:cytology* / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D009664:Norway; D010802:Phylogeny; D011529:Protozoan Infections, Animal / Q000469:parasitology* / Q000473:pathology; D020317:Salmo salar / Q000469:parasitology*; D012623:Seawater; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal