A parvicapsulid (Myxozoa) infecting Sprattus sprattus and Clupea harengus (Clupeidae) in the Northeast Atlantic uses Hydroides norvegicus (Serpulidae) as invertebrate host.

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.).

The marine myxosporean Sigmomyxa sphaerica (Thélohan, 1895) gen. n., comb. n. (syn. Myxidium sphaericum) from garfish (Belone belone (L.)) uses the polychaete Nereis pelagica L. as invertebrate host.

Sigmomyxa sphaerica (Thélohan, 1892) gen. n. (Myxozoa, Myxosporea) with myxosporean stages in the gall bladder of Belone belone (L.) (Teleostei, Belonidae) uses the polychaete Nereis pelagica L. (Nereidae) from shallow water in the northern Øresund, Denmark, as invertebrate host. The nearly spherical tetractinomyxon-type actinospores of S. sphaerica differ from those of two species of Ellipsomyxa which also use Nereis spp. as invertebrate host. Pansporocysts of S. sphaerica were not seen. S. sphaerica is redescribed on the basis of myxospore stages from B. belone and actinospores from N. pelagica, and the phylogenetic affinities examined on the basis of ribosomal small subunit gene sequences. S. sphaerica is closest related to Ellipsomyxa spp., and is not congeneric with morphologically similar Myxidium spp. from gadids. This is the fifth elucidated two-host life cycle of a marine myxozoan.

Morphology and SSU rDNA sequences of Ortholinea orientalis (Shul'man and Shul'man-Albova, 1953) (Myxozoa, Ortholineidae) from Clupea harengus and Sprattus sprattus (Clupeidae) from Denmark.

Ortholinea orientalis (Shul'man and Shul'man-Albova 1953) Shul'man 1956 is redescribed from Clupea harengus L. and Sprattus sprattus (L.) (Teleostei, Clupeidae) from the northern Øresund, Denmark. S. sprattus is a new host record. Polysporic plasmodia and most myxospores were found in the ureters of both hosts. The myxospores have external valvular ridges, which were not observed in the original description. The presence of this character causes us to consider Ortholinea clupeidae Aseeva 2000 as a likely synonym of O. orientalis. Ortholinea antipae Moshu and Trombitsky, 2006 from a Black Sea clupeid is also similar and represent a possible synonym. Sequence comparisons and phylogenetic analysis of partial SSU rDNA sequences of O. orientalis reveal closest affinity (82-86% identity) to members of the 'Freshwater Urinary Bladder Clade' sensu Fiala (2006), a clade among the Platysporina containing members of the myxosporean genera Myxobilatus, Hoferellus, Myxidium, Zschokkella and Chloromyxum from freshwater fishes.

Ellipsomyxa syngnathi sp. n. (Myxozoa, Myxosporea) in the pipefish Syngnathus typhle and S. rostellatus (Teleostei, Syngnathidae) from Denmark.

A new species Ellipsomyxa syngnathi sp. n. (Myxozoa) is described from Syngnathus typhle L. and Syngnathus rostellatus Nilsson, 1855 (Syngnathidae), using spore morphology and SSU rDNA sequence data. Monosporic plasmodia develop in the internal gallbladder wall. The ellipsoid myxospore has two pyriform polar capsules which discharge at opposite sides some distance from both sutural line and spore ends. The myxospore mainly differs from that of Ellipsomyxa gobii Køie (Folia Parasitol 50:269-271, 2003) in being monosporic and in having the sutural line oblique to the thickness axis. Zschokkella mugilis Sitjá-Bobadilla and Alvarez-Pellitero (J Euk Microbiol 40:755-764, 1993) is transferred to Ellipsomyxa as Ellipsomyxa mugilis comb. n.

Bipteria formosa (Kovaleva et Gaevskaya, 1979) comb. n. (Myxozoa: Myxosporea) in whiting Merlangius merlangus (Teleostei: Gadidae) from Denmark.

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 marine herring myxozoan Ceratomyxa auerbachi (Myxozoa: Ceratomyxidae) uses Chone infundibuliformis (Annelida: Polychaeta: Sabellidae) as invertebrate host.

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.

Parvicapsula bicornis n. sp. and P. limandae n. sp. (Myxozoa, Parvicapsulidae) in Pleuronectidae (Teleostei, Heterosomata) from Denmark.

Two species of Parvicapsula were found in the kidney tubules and the urinary bladder of 2 pleuronectid fish from the northern Oresund, Denmark. The coelozoic, spherical, disporic trophozoites of both species are 10 to 12 pm in diameter. The myxospores of both species are elongate, asymmetrical and slightly curved, and have spherical polar capsules. Parvicapsula bicornis n. sp. (6-8 x 5-6 microm, polar capsule 2.5 microm in diameter) occurs in Pleuronectes platessa. The polar capsules of P. bicornis are arranged symmetrically on either side of the longitudinal axis and its spores differ from other species of Parvicapsula in having two 2-3 microm long posterior processes of different length. Parvicapsula limandae n. sp. (8-11 x 4-5 pm, polar capsule 1.6 microm in diameter) is found in Limanda limanda. The polar capsules are arranged along the longitudinal axis. It differs from Parvicapsula unicornis Kabata, 1962, recorded from L. limanda, in the arrangement of the polar capsules and in the absence of a posterior horn-like projection. The phylogenetic relationship between P. bicornis n. sp., P. limandae n. sp. and other Parvicapsula spp. was examined with their partial small subunit rDNA (SSU rDNA) sequences. P. limandae n. sp. and P. asymmetrica appear to be closely related, while P. bicornis n. sp. and P. minibicornis are the most divergent members of the genus.

A new genus Gadimyxa with three new species (Myxozoa, Parvicapsulidae) parasitic in marine fish (Gadidae) and the two-host life cycle of Gadimyxa atlantica n. sp.

The myxozoans Gadimyxa atlantica n. sp. and G. sphaerica n. sp., and G. arctica n. sp. (Myxozoa, Parvicapsulidae), are described from Gadus morhua L. and Arctogadus glacialis (Peters) (Gadidae), respectively. They develop coelozoic in bisporic plasmodia in the urinary systems. Two morphological forms of spores were found in all 3 species, i.e., wide and (sub)spherical forms. Both spore types are bilaterally symmetrical along the suture line. The wide spores, semicircular in frontal view and elliptical in apical view, have 2 spherical polar capsules, which open in the sutural or median plane mid on the flat side of the spore. Mean widths of the wide spores of G. atlantica, G. sphaerica, and G. arctica are 7.5, 10.0, and 10.0 microm, respectively. The older, more thick-walled, (sub)spherical spores with binucleate sporoplasm are 8.0, 5.3, and 7.3 microm in mean width, respectively. The mean diameters of the polar capsules of (sub)spherical spores are 2.4, 1.7, and 2.2 microm, respectively. The (sub)spherical forms of Gadimyxa are most similar to Ortholinea within the Ortholineidae, but they differ in the development of the spores and in the arrangement of the polar capsules. The polychaetes Spirorbis spp. (Spirorbidae) act as invertebrate hosts of G. atlantica. The previously described actinospores of the tetractinomyxon type develop to myxospores in Gadus morhua within 8 wk. This is the second known myxozoan 2-host life cycle in the marine environment. Phylogenetic analyses based on partial small subunit rDNA sequences places Gadimyxa spp. among Parvicapsula spp. in the Parvicapsulidae.

The ultrastructure and reproduction of Amphiamblys capitellides (Microspora, Metchnikovellidae), a parasite of the gregarine Ancora sagittata (Apicomplexa, Lecudinidae), with redescription of the species and comments on the taxonomy.

The ultrastructural cytology and reproduction of the hyperparasitic microsporidium Amphiamblys capitellides (Caullery and Mesnil, 1897) is described. Merogonial reproduction was not observed. The sporogony comprises two sequences: a sac-bound sporogony in close contact with the cytoplasm of the host and a free sporogony in parasitophorous vacuoles. The free sporogony, which probably precedes the sac-bound, yields a small number of rounded spores. The sac-bound sporogony is polysporoblastic, generating two rows of elongated spores. All stages have isolated nuclei. Both spore types have an extrusion apparatus of the metchnikovellidean type, with a polar sac devoid of anchoring disc, a polar filament with one manubroid and one bulbous part, and a posterior semicircular membrane fold enclosing rounded or tubular structures. Hosts are gregarines of the species Ancora sagittata living in the intestine of polychaetes of the genus Capitella, probably the species Capitella giardi. The cytology, life cycle and classification are discussed. The species is redescribed and the diagnosis of the genus Amphiamblys Caullery and Mesnil, 1914 is emended.

Trilosporoides platessae gen. et sp. n. (Myxozoa: Multivalvulida) in the plaice Pleuronectes platessa (Teleostei: Pleuronectidae) from Denmark.

A new myxosporean species, Trilosporoides platessae gen. et sp. n. (Multivalvulida), is described from the gallbladder of the plaice Pleuronectes platessa L. (Pleuronectidae) from Denmark. The myxospore of T. platessae is conical in side view, with a 24 microm long, pointed posterior projection. In apical view, the myxospore (diameter 9.4 microm) is round, trilobed and with three spherical polar capsules arranged peripherally, equidistant and opening peripherally through protruding tips. The polar capsules are of different sizes, one often larger than the others (diameter 3.3 microm vs. 2.5 microm). Apart from the long posterior projection, the myxospore of T. platessae differs from those of the three known species of Trilospora Noble, 1959 and from all genera within the order Multivalvulida Shulman, 1959 in the arrangement of the polar capsules. Trilosporoides platessae may temporarily be placed in the vicinity of the Trilosporidae.

Ellipsomyxa gobii (Myxozoa: Ceratomyxidae) in the common goby Pomatoschistus microps (Teleostei: Gobiidae) uses Nereis spp. (Annelida: Polychaeta) as invertebrate hosts.

Nereis diversicolor O.F. Müller and N. succinea Frey et Leuckart (Polychaeta, Nereidae) living in brackish shallow areas in Denmark are naturally infected with tetractinomyxon actinospores. Infected Nereis spp. were experimentally fed to various potential fish hosts, and the actinosporean stages developed into myxosporean stages of Ellipsomyxa gobii Køie, 2003 (Ceratomyxidae) in the gallbladder of the common goby Pomatoschistus microps (Krøyer) (Gobiidae). The European eel Anguilla anguilla (L.), three-spined stickleback Gasterosteus aculeatus L., small sand eel Ammodytes tobianus L., flounder Platichthys flesus (L.), European plaice Pleuronectes platessa L. and common sole Solea solea (L.) did not become experimentally infected. In Danish shallow brackish areas P. microps is naturally infected with E. gobii, in some areas with a prevalence >90%. We compared small subunit ribosomal DNA sequences of the actinosporean with E. gobii from P. microps. Sequences were identical, which further verifies that both forms belong to the same organism. This is the first myxozoan two-host life cycle in the marine environment.

Parvicapsula spinachiae n.sp. (Myxozoa, Parvicapsulidae) in Spinachia spinachia (L.) (Teleostei, Gasterosteidae) from Denmark.

Parvicapsula spinachiae sp. nov. is described from Spinachia spinachia (L.) (Teleostei, Gasterosteidae) from the northern Øresund, Denmark. The subspherical disporous plasmodia occur in the renal tubules and urinary bladder; the myxospores were found only in the urinary bladder. The myxospores are ovoid when viewed frontally and curved when viewed laterally. Mean maximum length is 10 microm and mean maximum width 5 microm. They have two spherical polar capsules in the apex and irregular thickenings at the posterior end. The newly described species is compared with the ten known species of Parvicapsula. It is most similar to Parvicapsula unicornis Kabata, 1962 but differs from this species by lacking the prominent suture and the posterior horn-like projection.

Ellipsomyxa gobii gen. et sp. n. (Myxozoa: Ceratomyxidae) in the common goby Pomatoschistus microps (Teleostei: Gobiidae) from Denmark.

A new myxosporean species Ellipsomyxa gobii gen. et sp. n. is described from the common goby Pomatoschistus microps (Krøyer) (Perciformes, Gobiidae). Plasmodia with long branched pseudopodia in the gallbladder develop to subspherical bisporous plasmodia. The myxospores were found in the gallbladder, and the hepatic and bile ducts. The new genus is characterised by the morphology of the myxospores. The myxospores have smooth thin valves elongated in the direction perpendicular to the plane of the straight central transverse indistinct sutural line. The two spherical polar capsules open some distance from the sutural line on opposite sides. The new genus thereby differs from Leptotheca Thélohan, 1895. Ellipsomyxa gobii is tentatively placed in the Ceratomyxidae.