Update of the species of Myxosporea (Cnidaria, Myxozoa) described in South-American countries since January 2017

The Myxosporea subclass harbours cnidarians myxozoans adapted for parasitism that infect mainly fishes worldwide. A total of 159 myxosporean species were described in South American waters until December 2016. These species were distributed by 24 genera, infecting 114 different host species in seven countries. Here, we present an update of the species described in South American countries from January 2017 to the present date, or those for which molecular data were made available in GenBank during this period. A total of 105 species distributed by 13 genera, parasitizing 59 host species are depicted in tabulated format including the species characteristics. Reports of infection with these parasites were found only in Argentina, Brazil, Colombia, and Peru. The most common parasites were Myxobolus spp. and Henneguya spp., and freshwater fish were about four times more parasitized than saltwater ones. Thus, the knowledge of myxosporean diversity in South America seems to be shaped more by the presence of research groups in each country than by the continent’s biogeographical conditions. In recent years, freshwater ecosystems in South America have become the site of discovery for a significant diversity of myxosporean genera previously associated with marine environments.