title: Morphological and ultrastructural aspects of Myxobolus niger n. sp. (Myxozoa) gill parasite of Corydoras melini (Siluriformes: Callichthyidae) from Brazilian Amazon.
abstract: Myxobolus niger n. sp. (Myxozoa) is described in the connective tissue of the serosa layer of the gill arch of Corydoras melini (Callichthyidae) captured from the Negro River, Amazonas State, Brazil. The prevalence of the parasite was 20% and the range intensity was 1-2 cysts per fish. The plasmodia were white and spherical to ellipsoidal, measuring 175 μm in diameter and were surrounded by a well-defined capsule of host connective tissue, with distinct delicate and interlaced collagen fibers. The myxospores body was ellipsoidal in frontal view and biconvex in sutural view. Spore dimensions were 11.3 ± 0.4 μm in length, 6.8 ± 0.2 μm in width and 4.1 ± 0.2 μm in thickness. The valves were symmetrical and smooth. The two polar capsules were elongated as pyriform and equal in size, measure 5.0 ± 0.3 μm in length and 2.0 ± 0.1 μm in width. The polar capsule had six to seven polar filament turns. Some aberrant spores were round in shape and had three polar capsules. The sporoplasm was binucleated and contained moderated number of sporoplasmosomes. The development of the plasmodia was asynchronic, with mature and immature spores. The plasmodium had moderated pynocitic channels. There were no projections, no invaginations and no microvilli in the plasmodial wall. This study is the first description of Myxobolus species in the fish of the Callichthyidae family.
authors.affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Avenida Bertrand Russel, s/n, Caixa Postal 6109, CEP 13083-970 Campinas, SP, Brazil. Electronic address: patrickmathews83@gmail.com.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Mathews
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Rua Duque de Caxias Norte, 225, CEP 13635-900 Pirassununga, SP, Brazil.
authors.forename: Antônio A M
authors.initials: AAM
authors.lastname: Maia
authors.affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Avenida Bertrand Russel, s/n, Caixa Postal 6109, CEP 13083-970 Campinas, SP, Brazil; Departamento de Ciências Biológicas, Universidade Federal de São Paulo, Rua Professor Arthur Riedel, 275, Jardim Eldorado, 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; D002397:Catfishes / Q000469:parasitology*; D005393:Fish Diseases / Q000469:parasitology; D005880:Gills / Q000469:parasitology*; D055766:Myxobolus / Q000166:cytology / Q000648:ultrastructure*
keywords: Amazon; Fish parasite; Myxozoa; Ornamental fish; Ultrastructure