A myxosporean producing actinospores of the tetractinomyxon type in Hydroides norvegicus Gunnerus (Serpulidae) in Denmark was identified as a member of the family Parvicapsulidae based on small-subunit ribosomal DNA (SSU rDNA) sequences. Myxosporean samples from various Danish and Norwegian marine fishes were examined with primers that detect the novel myxosporean. Sprattus sprattus (Linnaeus) and Clupea harengus Linnaeus (Teleostei, Clupeidae) were found to be infected. The sequences of this parvicapsulid from these hosts were consistently slightly different (0.8% divergence), but both these genotypes were found in H. norvegicus. Disporic trophozoites and minute spores of a novel myxosporean type were observed in the renal tubules of some of the hosts found infected through PCR. The spores appear most similar to those of species of Gadimyxa Køie, Karlsbakk et Nylund, 2007, but are much smaller. The actinospores of the tetractinomyxon type from H. norvegicus have been described previously. In GenBank, the SSU rDNA sequences of Parvicapsulidae gen. sp. show highest identity (82%) with Parvicapsula minibicornis Kent, Whitaker et Dawe, 1997 infecting salmonids (Oncorhynchus spp.) in fresh water in the western North America. A phylogenetic analysis places P. minibicornis and Parvicapsulidae gen. sp. in a sister clade to the other parvicapsulids (Parvicapsula spp. and Gadimyxa spp.).
A total of 22 specimens of whiting Merlangius merlangus (L.) (Teleostei, Gadidae) from the northern Øresund, Denmark were examined for Myxosporea. Zschokkella hildae Auerbach, 1910 (Myxidiidae), Gadimyxa sp. (Parvicapsulidae) and a species of Bipteria occurred in the renal tubules of 9%, 18% and 68% whiting, respectively. Immature spores of the Bipteria species are very similar to spores of Myxoproteus formosus Kovaleva et Gaevskaya, 1979 originally described from the urinary system of whiting from the Celtic Sea. We therefore consider Bipteria sp. from whiting in Denmark conspecific with M. formosus and propose Bipteria formosa (Kovaleva et Gaevskaya, 1979) comb. n. The spore of Bipteria formosa is described in detail and compared with other Bipteria spp. The phylogenetic position of B. formosa, based on partial 18S rDNA sequences, is closest to Leptotheca fugu Tun, Yokoyama, Ogawa et Wakabayashi, 2000 and the Sphaerosporidae.
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 blood from laboratory-reared cod (Gadus morhua) and halibut (Hippoglossus hippoglossus). Some experimental halibut acquired trypanosome infection, with parasitaemia between ca. 500 and 60,000 trypanosomes ml-1. The trypanosomes were of variable size and measured 39-90 µm (mean 57 µm) ca. 81 days post-infection. Characteristic features are cell striation, refractile cytoplasmic granules, anterior nucleus and a relatively long (ca. 6 µm, max 9 µm) distance from the posterior end to the kinetoplast. Following growth, the trypanosomes became increasingly slender, with fewer striae and a nucleus position less pronounced anterior. The trypanosome is considered distinct from a type transmitted by the leech Calliobdella nodulifera (Malm, 1863) in the NE Atlantic, but is regarded conspecific with a trypanosome transmitted by J. arctica in the NW Atlantic. This trypanosome has in the past been identified as Trypanosoma murmanensis Nikitin, 1927, a poorly described species. T. murmanensis cannot be recognized with certainty among the trypanosomes transmitted by C. nodulifera and J. arctica respectively. We propose that the J. arctica-transmitted species is considered T. murmanensis Nikitin, 1927 sensu stricto.
Sphaeromyxa artedielli sp. n. is described from the gall bladder of the Atlantic hookear sculpin Artediellus atlanticus Jordan et Evermann (Cottidae; type host) from northern Norway. The parasite was also found to infect Triglops murrayi Günther (Cottidae). Spores are produced in disporic pansporoblasts in large flat plasmodia. Spores are straight and fusiform with truncated ends, and measure 16.5-18.7 µm × 4.9-6.2 µm. Valves are thick, striated and suture line is straight. Two equal ovoid polar capsules measure 4.2-6.8 µm × 2.9-4.4 µm and contain irregularly folded polar filaments. Distinctive features include spore shape and size, spore length/width relationship, striated valves, equal polar capsules and a short intercapsular distance. Sphaeromyxa bonaerensis Timi et Sardella, 1998, Sphaeromyxa cannolii Sears, Anderson et Greiner, 2011, and Sphaeromyxa sevastopoli Naidenova, 1970 produce straight spores with truncated ends that are of similar length as those of the new species. Sphaeromyxa cannolii differs in showing smooth spores with unequal polar capsules. The new species differs from S. bonaerensis and S. sevastopoli in significantly wider spores and polar capsules. Sphaeromyxa balbianii Thélohan, 1892, a species originally described with significantly smaller spores than S. artedielli sp. n., has previously been recorded from T. murrayi. We show that S. artedielli sp. n. differs from S. balbianii from the type host Gaidropsarus vulgaris (Cloquet) by its SSU rDNA sequence, and suggest that Atlantic records of Sphaeromyxa spp. from T. murrayi represent S. artedielli sp. n. The closest relative to S. artedielli sp. n. according to the SSU rDNA sequences, S. longa Dunkerly, 1921, differs clearly by spore size and shape. In the SSU rDNA-based phylogenetic analyses, S. artedielli sp. n. groups with other Sphaeromyxa spp. with straight spores and truncated ends in a clade that represents a sister-group to Sphaeromyxa spp. with arcuate spores and rounded ends. Our results indicate that an SSU rDNA pseudogene is present in S. balbianii.
Sequencing of SSU rDNA showed that actinospores of the tetractinomyxon type, which develop in Chone infundibuliformis Krøyer (Annelida, Polychaeta, Sabellidae) from the northern Øresund, Denmark, are identical with Ceratomyxa auerbachi Kabata, 1962 (Myxozoa, Ceratomyxidae). This myxosporean was found in the gallbladder of the Atlantic herring Clupea harengus L. from the northern Øresund, Denmark, and from the Bergen area, western Norway. The pansporocysts and actinospores of C. auerbachi are described. This is the third elucidated two-host life cycle of a marine myxozoan, and the first involving a marine ceratomyxid.