Protozoan parasites of the genus Perkinsus are considered important pathogens responsible for mass mortalities in several mollusk species worldwide. In the present study we describe for the first time a parasite of the genus Perkinsus infecting the mangrove oyster Crassostrea rhizophorae from the Brazilian coast. Prevalence of this parasite was low in the Pacoti River estuary (Ceará, northeast Brazil) and absent in oysters from southern Brazil. Oyster gill and rectum tissues incubated in Ray's fluid thioglycollate medium (RFTM) revealed the presence of spherical hypnospores (5 to 55 µm diam.). Histological analysis showed the occurrence of typical signet-ring trophozoites and schizonts (3 to 6 µm diam.) infecting connective tissues of several organs and digestive epithelia. PCR assays specific to the genus Perkinsus, followed by cloning and sequencing of the internal transcribed spacer (ITS) region of the ribosomal ribonucleic acid (rRNA) gene complex, confirmed a close phylogenetic relationship between Brazilian Perkinsus sp. and P. beihaiensis infecting Chinese oysters. KEY WORDS: Crassostrea rhizophorae · Mangrove oyster · Perkinsus sp. · Protozoan parasite · PCR-RFLP · rRNA · RFTM · Sporulation Resale or republication not permitted without written consent of the publisherDis Aquat Org 88: [13][14][15][16][17][18][19][20][21][22][23] 2009 eases affecting edible and cultured bivalve species from 2 Brazilian regions. The project was designed to survey parasites among wild and cultivated populations of oysters Crassostrea rhizophorae and C. gigas from Santa Catarina Island and the Pacoti River estuary (Fortaleza, in the state of Ceará, northeast Brazil). The results provide data on distributions of pathogens and on host susceptibilities to pathogens, which will qualify further monitoring programs, help avoid disease transfers from infected populations, and inform efforts to keep unaffected areas parasite-free.The first described parasite of the genus Perkinsus was P. marinus (Mackin et al. 1950), which was identified as being responsible for mortality outbreaks among Crassostrea virginica oyster stocks from Louisiana, USA. It was first described as Dermocystidium marinum, based partly on characteristics of hypertrophic hypnospores and zoosporangia that enlarge among infected oyster tissues when they are incubated in a high-salt formulation of Ray's fluid thioglycollate medium (RFTM) (Ray 1952). Since that time, diverse Perkinsus spp. have been reported to infect many important commercially cultured mollusk species worldwide.Perkinsus olseni was first described as a pathogen of Australian abalone Haliotis ruber (Lester & Davis 1981). Azevedo (1989) described the species P. atlanticus infecting the carpet shell clam Ruditapes decussatus in Portugal. P. olseni, which is currently synonymous with P. atlanticus, has wide geographic and host ranges. It has subsequently been reported in other bivalve species, such as Pitar rostrata from Uruguay (Cremonte et al. 2005) and R. philippinarum, Venerupis pullast...

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Parasitas em ostras de cultivo (Crassostrea rhizophorae e Crassostrea gigas)da Ponta do Sambaqui, Florianópolis, SC

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Berbigões, Anomalocardia brasiliana (Gmelin, 1791), de bancos naturais da Ilha de Santa Catarina e região continental adjacente (SC, Brasil), foram examinados quanto a presença de simbiontes. Holothuriophilus tomentosus (Ortmann, 1894) (Brachyura), Sphenia antillensis Dall & Simpson, 1901 (Bivalvia) e poliquetos espionídeos (Polychaeta) foram observados macroscopicamente. A análise das secções histológicas evidenciou esporocistos de trematódeos (Digenea), um metacestóide (Cestoda) e dois ciliados (Ciliophora).