Morphological and molecular analysis of Myxobolus malabaricus n. sp. (Myxosporea: Myxozoa) parasitizing Hoplias malabaricus in Amazon basin.

The present study identified an undescribed myxozoan parasite species infecting Hoplias malabaricus specimens collected from the Arari River, in the municipality of Cachoeira do Arari in the state of Pará, northern Brazil. Thirty specimens were necropsied to search for microparasite, and when plasmodium found, material was collected for analysis via light microscopy, histology and molecular biology methodologies. Macroscopic plasmodium was observed in the gills of 30% of the examined specimens. Microscopic analysis of the plasmodium revealed the presence of myxospores belonging to the genus Myxobolus. These myxospores were distinguished from other Myxobolus species that parasitize freshwater Amazonian fish based on their overall morphology, morphometry and partial sequence (1,452 base pairs) of the SSU rDNA gene. These analyses revealed the existence of a new species of Myxobolus, named Myxobolus malabaricus n. sp. The new species is clearly distinct from other Myxozoa and may be an important parasite for causing disease in the gills of H. malabaricus, an important species of the Amazonian teleost fauna.