Monogenoidea represents a class of hermaphroditic Platyhelminthes ecto-parasitic of mainly fishes. They inhabit the gills, skin, nasal fossae, ureters and some intestinal ducts. Brazil is known as a country with rich fauna, flora and mineral resources, with more than 4000 species of freshwater fishes, representing approximately 31% of the world freshwater fish species. Abou 365 species of Monogenoidea described from Brazil is listed. The International Symposium on Monogenea (ISM) represents the most traditional event for researchers worldwide that study this group of parasites. During the Sixth ISM, in South Africa, Brazil had being elected the next venue (ISM 7). This is the first time in American continent that will enable the participation of researchers and students of the whole continent.

A new species of Rhinoxenoides was described parasitizing the gill filaments of neotropical triportheid fishes. The new species was described from Triportheus angulatus (Spix & Agassiz, 1829) from the Juruá River, State of Acre, Brazil. Rhinoxenoides cruzeirensis n. sp. resembles Rhinoxenoides horacioschneideri Santos Neto, Costa, Soares & Domingues, 2018, mainly by presenting a coiled male copulatory organ (MCO) with clockwise rings; accessory piece with articulation process extending within the coils to the base of MCO; dorsal anchor with well-developed superficial root, and dorsal bar absent. However, it differs from this by number of the coils of the MCO; accessory piece formed by a straight piece that expands in the middle, where it folds over itself; ventral bar short and robust; dorsal anchor with a well-developed superficial root twice as long as the deep root, with a sm...

Contracaecum pelagicum Johnston & Mawson, 1942 y Seuratia shipleyi (Stossich, 1900) están registrados en Brasil parasitando Calonectris borealis (Cory, 1881), que es un nuevo huésped para ambas especies. Se presentam las principales medidas de estas especies en el nuevo huésped.

Se presenta una lista completa de las 432 especies de Cestoda que se han descrito y / o registrados en Brasil. Se distribuyen através de 15 órdenes y 36 familias; 50 especies no fueron identificadas y 9 se consideran species inquirenda. Entre los peces, Zungaro zungaro (Humboldt in Humboldt & Valenciennes, 1821) fue el hospedador que fue más parasitadas (con 18 especies de cestodos); entre los anfibios, fue Rhinella icterica Spix, 1824, con 3 especies; y entre los reptiles, fue Bothrops jararaca (Wied-Neuwied, 1824), con 7 especies. Entre las aves, Gallus gallus (Linnaeus, 1758) presentó el mayor numero de asociaciones con cestodos, de tal manera que 13 especies se han registrado en Brasil y teniendo en cuenta los mamíferos, Homo sapiens (Linnaeus, 1758) presentan 13 especies diferentes. Pocos representantes de estas especies de cestode se reportaran de invertebrados. El pequeño n�...

Parasites are important components of global biodiversity and among them, the Monogenoidea stands out, as parasites of fishes, commonly affecting the gills of their hosts. The aim of the present study was to analyze the presence of species of Urocleidoides parasitizing characiform fishes from the Tocantins River. During the study, specimens of Psectrogaster amazonica Eigenmann & Eigenmann and Caenotropus labyrinthicus (Kner) were collected from the urban zone of the municipality of Imperatriz, state of Maranhão. The gills of the fishes were removed and placed in vials containing hot water (65°C), and posteriorly, absolute ethanol was added to reach a concentration of 70%. A new species of Urocleidoides was described parasitizing both hosts. Urocleidoides psectrogasteri n. sp. can be distinguished by its congeners species principally by the morphology of the MCO.  Besides, the know...

Anacanthorus Mizelle & Price, 1965 is the most diverse genus of Dactylogyridae and is characterized by the absence of anchors and bars in the haptor. Members of Anacanthorus are found parasitizing until now only fishes belonging to order Characiformes. Specimens of Brycon pesu Müller & Troschel, 1845 and Caenotropus labyrinthicus (Kner, 1858) were collected from Tocantins River, Brazil and had their gills removed and individualized in bottles containing water heated to (~65ºC), to relax and release the parasites, and ethanol absolute was increased to reach the concentration of 70%. The parasites found were collected and mounted in Hoyer´s medium. A new species of Anacanthorus, A. itaueirasensis sp. nov., is described from Brycon pesu, presenting the characteristics of Anacanthorus species parasitic on bryconids, as morphology of the copulatory complex, composed of a tubular MC...