Taxonomia, morfologia e filogenia molecular de ciliados tricodinídeos (Ciliophora, Mobilida, Trichodinidae) ectoparasitos de copépodos e peixes encontrados em ecossistemas dulcícolas neotropicais

Abstract

The tricodinids ciliates (Mobilida: Trichodinidae) have about 300 species. They are aquatic, ectocomensal organisms that may eventually parasite fish, molluscs, amphibians, crustaceans and cnidarians. Trichodinids attach to their hosts by a complex adhesive disk located in the aboral region of their body. An important component of this adhesive disk complex are the denticles, which are proteinaceous structures and have important taxonomic value for the family. The most representative genus of this family is Trichodina, with about 270 described species and it has the most derived denticle, composed by blade, central part and radius. The major number of tricodinids studies were performed in fishes, due to the due to their economic value, once tricodinids parasites damage their hosts causing weakness, growth reducing, lamellar hyperplasia, erratic swimming and in many cases may lead to death. Few are the works with other groups of hosts and the diversity of these ciliates remains unknown. Recently work with molecular characterization of these microeucariotos has grown, increasing a little our knowledge about the phylogenetic relationships between its species. The present work includes, in section I, trichodinid records from a poor sampled area in southeastern Brazil, in addition a high unprecedented richness of those parasites in few Oreochromis niloticus specimens, a new record of the genus Trichodinella to Brazilian waters, besides the occurrence of trichodinids in adult fish, wich is not recurrent. Session II brings the first molecular characterization of the species Trichodina diaptomi, and a discussion on the influence of host type on morphology of trichodinid.