Morphological, histopathological, and phylogenetic insights on a new calyptospora species that causes hepatic coccidiosis in a fish from the Brazilian amazon.

Calyptosporidae are heteroxenous coccidia with fish as their definitive hosts. Currently, most of this diversity is found in freshwater fish from the Brazilian Amazon region. The objective of this study was to perform an integrative taxonomy of a new species of Calyptospora in Cynoscion virescens (Cuvier, 1830), a marine and estuarine fish. Thirty specimens of C. virescens from the Eastern Amazon were collected and necropsied, of which 12 (40 %) were infected after microscopic analysis, which has revealed spherical oocysts measuring 17.8 μm in diameter and four elliptical sporocysts with 7.1 μm in length and 6.1 μm in width. The oocysts were located in the hepatopancreas, and melanomacrophagic bodies were observed in nearby regions. In phylogenetic analysis, coccidia were found in the basal clade of the Calyptosporidae family. Morphological and molecular divergence characterized a new species of Calyptospora in C. virescens, the first occurrence of coccidia in a fish of the family Sciaenidae.