title: Amazonian waters harbour an ancient freshwater Ceratomyxa lineage (Cnidaria: Myxosporea).
abstract: A new species of Ceratomyxa parasitizing the gall bladder of Cichla monoculus, an endemic cichlid fish from the Amazon basin in Brazil, is described using morphological and molecular data. In the bile, both immature and mature myxospores were found floating freely or inside elongated plasmodia: length 304 (196-402) μm and width 35.7 (18.3-55.1) μm. Mature spores were elongated and only slightly crescent-shaped in frontal view with a prominent sutural line between two valve cells, which had rounded ends. Measurements of formalin-fixed myxospores: length 6.3±0.6 (5.1-7.5) μm, thickness 41.2±2.9 (37.1-47.6) μm, posterior angle 147°. Lateral projections slightly asymmetric, with lengths 19.3±1.4μm and 20.5±1.3μm. Two ovoid, equal size polar capsules, length 2.6±0.3 (2-3.3) μm, width 2.5±0.4 (1.8-3.7) μm, located adjacent to the suture and containing polar filaments with 3-4 turns. The small subunit ribosomal DNA sequence of 1605 nt was no more than 97% similar to any other sequence in GenBank, and together with the host, locality and morphometric data, supports diagnosis of the parasite as a new species, Ceratomyxa brasiliensis n. sp. Maximum parsimony and maximum likelihood analyses showed that C. brasiliensis n. sp. clustered within the marine Ceratomyxa clade, but was in a basally divergent lineage with two other freshwater species from the Amazon basin. Our results are consistent with previous studies that show Ceratomyxa species can cluster according to both geography and host ecotype, and that the few known freshwater species diverged from marine cousins relatively early in evolution of the genus, possibly driven by marine incursions into riverine environments.
authors.affiliation: Department of Animal Biology, Institute of Biology, University of Campinas, Rua Monteiro Lobato, 255, CEP 13083-862, Campinas, SP, Brazil.
authors.forename: Suellen A
authors.initials: SA
authors.lastname: Zatti
authors.affiliation: Department of Microbiology, Oregon State University, 97331, Corvallis, OR, USA.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Atkinson
authors.affiliation: Department of Microbiology, Oregon State University, 97331, Corvallis, OR, USA.
authors.forename: Jerri L
authors.initials: JL
authors.lastname: Bartholomew
authors.affiliation: Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, São Paulo University, Avenida Duque de Caxias Norte, 225, CEP 13635-900, Pirassununga, SP, Brazil.
authors.forename: Antônio A M
authors.initials: AAM
authors.lastname: Maia
authors.affiliation: Department of Animal Biology, Institute of Biology, University of Campinas, Rua Monteiro Lobato, 255, CEP 13083-862, Campinas, SP, Brazil; Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Rua Professor Arthur Riedel, 275, Jardim Eldorado, CEP 09972-270, Diadema, SP, Brazil. Electronic address: edapadriano@gmail.com.
authors.forename: Edson A
authors.initials: EA
authors.lastname: Adriano
mesh_terms: D000818:Animals; D001938:Brazil; D003063:Cnidaria / Q000235:genetics; D004275:DNA, Ribosomal; D005393:Fish Diseases / Q000469:parasitology*; D005618:Fresh Water; D005704:Gallbladder; D005705:Gallbladder Diseases / Q000469:parasitology*; D055764:Myxozoa / Q000235:genetics / Q000469:parasitology*; D010802:Phylogeny
chemical_list: D004275:DNA, Ribosomal
keywords: Amazon; Ceratomyxa; Freshwater environment; Myxozoa; ssrDNA sequencing