The Patagonian seabass Acanthistius patachonicus (Jenyns, 1840) (Serranidae) is a marine fish valued for commercial and sport fisheries from Argentina. We report a new myxosporean (Cnidaria: Myxozoa) infecting the urinary system of the Patagonian seabass from San Antonio Bay, San Matías Gulf, on the Atlantic Ocean. The mature myxospores were subspherical, 8.2-11.0 μm × 7.9-11.0 μm and 7.7-9.0 μm in thickness; two subspherical polar capsules, 2.4-3.8 μm × 2.3-3.6 μm, with 3 to 4 turns of the polar tubule; openings on different valves in almost opposite directions. Ornamented shell valves exhibited 17-20 concentrically organized surface ridges. SSU rDNA phylogenetics analyses placed the new species in the freshwater urinary tract clade, clustering in a clade formed by Myxobilatus gasterostei (Parisi, 1912), Acauda hoffmani Whipps, 2011, and other Ortholinea spp. Based on spore morphology, site of infection, and molecular data, we described this myxozoan as Ortholinea concentrica n. sp.

• Keywords
• Marine fish, Myxozoa, Phylogeny, SSU rDNA, South America, Taxonomy, Urinary system,
• MeSH
• Phylogeny MeSH
• Urinary Tract parasitology   MeSH
• Myxozoa * classification   genetics   isolation & purification   MeSH
• Fish Diseases parasitology   MeSH
• Parasitic Diseases, Animal parasitology   MeSH
• Bass parasitology   MeSH
• DNA, Ribosomal genetics   MeSH
• Spores classification   MeSH
• Animals MeSH
• Check Tag
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Argentina MeSH
• Atlantic Ocean MeSH
• Names of Substances
• DNA, Ribosomal MeSH

INTRODUCTION: Intertidal rock pools where fish and invertebrates are in constant close contact due to limited space and water level fluctuations represent ideal conditions to promote life cycles in parasites using these two alternate hosts and to study speciation processes that could contribute to understanding the roles of parasitic species in such ecosystems. MATERIAL AND METHODS: Gall bladder and liver samples from five clinid fish species (Blenniiformes: Clinidae) were morphologically and molecularly examined to determine the diversity, prevalence, distribution and host specificity of Ceratomyxa parasites (Cnidaria: Myxozoa) in intertidal habitats along the coast of South Africa. Phylogenetic relationships of clinid ceratomyxids based on the SSU rDNA, LSU rDNA and ITS regions were assessed additionally to the investigation of population genetic structure of Ceratomyxa cottoidii and subsequent comparison with the data known from type fish host Clinus cottoides. RESULTS AND DISCUSSION: Seven Ceratomyxa species including previously described Ceratomyxa dehoopi and C. cottoidii were recognized in clinids. They represent a diverse group of rapidly evolving, closely related species with a remarkably high prevalence in their hosts, little host specificity and frequent concurrent infections, most probably as a result of parasite radiation after multiple speciation events triggered by limited host dispersal within restricted spaces. C. cottoidii represents the most common clinid parasite with a population structure characterized by young expanding populations in the south west and south east coast and by older populations in equilibrium on the west coast of its distribution. Parasite and fish host population structures show overlapping patterns and are very likely affected by similar oceanographic barriers possibly due to reduced host dispersal enhancing parasite community differentiation. While fish host specificity had little impact on parasite population structure, the habitat preference of the alternate invertebrate host as well as tidal water exchange may be additional crucial variables affecting the dispersal and associated population structure of C. cottoidii.

• MeSH
• Phylogeny MeSH
• Host-Parasite Interactions genetics   physiology   MeSH
• Myxozoa classification   genetics   MeSH
• Fish Diseases parasitology   MeSH
• Parasitic Diseases, Animal parasitology   MeSH
• Parasites classification   genetics   MeSH
• Genetics, Population methods   MeSH
• DNA, Ribosomal genetics   MeSH
• Fishes parasitology   MeSH
• Life Cycle Stages genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• South Africa MeSH
• Names of Substances
• DNA, Ribosomal MeSH