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Diseases of Aquatic Organisms

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DAO 128:37-49 (2018)  -  DOI: https://doi.org/10.3354/dao03210

New myxosporeans parasitizing Phractocephalus hemioliopterus from Brazil: morphology, ultrastructure and SSU-rDNA sequencing

Juliana Naldoni1,*, Antônio A. M. Maia2, Lincoln L. Correa3, Marcia R. M. da Silva2, Edson A. Adriano1,4

1Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Paulo (UNIFESP), Rua Professor Artur Riedel, 275, Jardim Eldorado, CEP 09972-270, Diadema, SP, Brazil
2Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo (USP), Rua Duque de Caxias Norte, 225, CEP 13635-900, Pirassununga, SP, Brazil
3Instituto de Ciências e Tecnologia das Águas, Universidade Federal do Oeste do Pará (UFOPA), Travessa Professor Antônio Carvalho Fátima, CEP 68040470, Santarém, PA, Brazil
4Departamento de Biologia Animal, Universidade Estadual de Campinas (UNICAMP), Rua Monteiro Lobato, 255, CEP 13083-970, Campinas, SP, Brazil
*Corresponding author:

ABSTRACT: Myxozoans are a diverse group of parasitic cnidarians, with some species recognized as serious pathogens to their hosts. The present study describes 2 new myxobolid species (Myxobolus figueirae sp. nov. and Henneguya santarenensis sp. nov.) infecting skin and gill filaments of the Amazonian pimelodid fish Phractocephalus hemioliopterus, based on ultrastructural, histology and phylogenetic analysis. The fish were caught in the Amazon River, Pará, Brazil. The plasmodial development of M. figueirae sp. nov. was in the dermis and those of H. santarenensis sp. nov. were of the intralamellar type. For both species, the plasmodia were surrounded by a connective tissue layer, but there was no inflammatory infiltrate. For M. figueirae sp. nov., mature spores were ovoid measuring 9.1 to 10 (9.5 ± 0.3) µm in length, 5.8 to 6.9 (6.4 ± 0.3) µm in width and 4.4 to 4.5 (4.5 ± 0.1) µm in thickness. Two polar capsules were elongated and of unequal size. For H. santarenensis sp. nov., mature spores were ellipsoidal in the frontal view, measuring 26.3 to 36.1 (31.9 ± 3) µm in total length, 9.6 to 11.9 (10.8 ± 0.5) µm in body length, 3.7 to 4.9 (4.3 ± 0.3) µm in width and 16.6 to 25.6 (21 ± 3.1) µm in caudal process. The polar capsules were elongated and of equal size. Phylogenetic analysis, based on partial small subunit ribosomal DNA (SSU rDNA) sequences and using the closest myxozoan sequences to each one of the species studied here based on previous GenBank data, showed M. figueirae sp. nov. and H. santarenensis sp. nov. clustering in distinct lineages. While H. santarenensis sp. nov. clustered in a well-supported subclade composed of Henneguya species that infect gills of South American pimelodid hosts, M. figueirae sp. nov. clustered in a weakly supported subclade containing parasite species of bryconid hosts.


KEY WORDS: Myxosporea · Myxobolus figueirae · Henneguya santarenensis · Ultrastructure · Histology · Amazon · Brazil


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Cite this article as: Naldoni J, Maia AAM, Correa LL, Silva MRM, Adriano EA (2018) New myxosporeans parasitizing Phractocephalus hemioliopterus from Brazil: morphology, ultrastructure and SSU-rDNA sequencing. Dis Aquat Org 128:37-49. https://doi.org/10.3354/dao03210

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