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Zoosporic parasites have received increased attention during the last years, but it is still largely unnoted that these parasites can themselves be infected by hyperparasites. Some members of the Chytridiomycota, Blastocladiomycota, Cryptomycota, Hyphochytriomycota, Labyrinthulomycota, Oomycota, and Phytomyxea are hyperparasites of zoosporic hosts. Because of sometimes complex tripartite interactions between hyperparasite, their parasite-host, and the primary host, hyperparasites can be difficult to detect and monitor. Some of these hyperparasites use similar mechanisms as their parasite-hosts to find and infect their target and to access food resources. The life cycle of zoosporic hyperparasites is usually shorter than the life cycle of their hosts, so hyperparasites may accelerate the turnaround times of nutrients within the ecosystem. Hyperparasites may increase the complexity of food webs and play significant roles in regulating population sizes and population dynamics of their hosts. We suggest that hyperparasites lengthen food chains but can also play a role in conducting or suppressing diseases of animals, plants, or algae. Hyperparasites can significantly impact ecosystems in various ways, therefore it is important to increase our understanding about these cryptic and diverse organisms.

Zoosporic true fungi and fungal-like organisms include unrelated groups in the kingdoms Fungi, Straminipila and Protozoa. There is very little information on the diversity of these organisms in many ecosystems of great biodiversity, particularly tropical or neotropical areas. Research assessing their diversity has been mainly conducted in Argentina and Brazil using multiple baiting techniques, resulting in the discovery of many new taxa and new records. To date, 434 species in these groups have been recorded for both countries. Continuing research is necessary to provide a more comprehensive understanding of their diversity in South America. Few specialists are available to study such extensive areas, which are being degraded by deforestation, land/clearing, pollution and other anthropogenic activities that affect the habitat of these organisms, long before surveys can be carried out by mycologists and protistologists. Hence, attempts to gather information about the diversity of zoosporic true fungi, heterotrophic Straminipila and Plasmodiophorids from South America are urgently needed, and should receive high priority., Los hongos zoospóricos verdaderos, los straminipilas heterotróficos y los plasmodioforidios, son grupos de organismos filogenéticamente no relacionados pertenecientes a los reinos Fungi, Straminipila y Protozoa. Existe escasa información disponible acerca de estos organismos en ecosistemas de gran biodiversidad, particularmente en áreas tropicales y neotropicales. En Sudamérica, las investigaciones sobre su diversidad han sido principalmente realizadas en Argentina y en Brasil utilizando técnicas de cebado múltiple, resultando en el descubrimiento de nuevos taxones y nuevas citas. Hasta el momento, en ambos países se han registrado 434 especies pertenecientes a estos grupos, lo que demuestra que se necesitan más investigaciones para ampliar su conocimiento en Sudamérica. Existen pocos especialistas disponibles para estudiar áreas tan extensas, las cuales están siendo degradadas por la deforestación, la contaminación, y otras actividades antrópicas que afectan el hábitat de estos organismos, antes de que su diversidad pueda ser estudiada por micólogos y protistólogos. De esta forma, los estudios tendientes a reunir información sobre la diversidad de los hongos zoospóricos verdaderos, los Straminipilas heterotróficos y los Plasmodioforidios deben ser considerados altamente prioritarios en Sudamérica., Instituto de Botánica "Dr. Carlos Spegazzini"

International audience

Zoosporic fungi (Chytridiomycota, Hyphochytridiomycota and Peronosporomycota) include organisms that occur as saprotrophs on vegetable debris or as parasites of invertebrates, plants, algae and of other zoosporic fungi. Water samples and floating organic matter were collected during a 2005-2006 survey at Las Cañas stream and Villa Elisa channel (Reserva Natural Selva Marginal Punta Lara, Pdo. de Ensenada, Bs. As.), and samples were processed with the baiting technique. Six taxa of parasitic zoosporic fungi were recovered: Olpidium sp. (Braun) Rabenhorst, Chytridium sp. Braun and Rhizophydium carpophyllum (Chytridiomycota), Rhizidiomyces apophysatus and R. hirsutus (Hyphochytridiomycota), Olpidiopsis pythii (Butler) Karling and Dictyuchus sp. Leitgeb, (Peronosporomycota). Olpidiopsis pythii is the first record for Argentina and South America., Facultad de Ciencias Naturales y Museo

El género Nowakowskiella comprende organismos acuáticos y terrestres, que se encuentran como saprótrofos principalmente sobre restos vegetales en descomposición. El género es citado por primera vez para Argentina y en esta contribución, se describen cuatro especies, analizándose su frecuencia y abundancia en los ambientes estudiados, brindándose una clave basada en caracteres morfológicos para diferenciarlas., The genus Nowakowskiella (Cladochytriaceae, Chytridiomycota) in environments of Buenos Aires Province (Argentina): Taxonomy, frequency and abundance of the found species.The genus Nowakowskiella comprises aquatic and terrestrial organisms, which occur as saprotrophs on decomposed vegetable debris mainly. This genus is recorded for the first time in Argentina and in this contribution four species are described, analyzing their frequency and abundance in the studied environments and providing an identification key based on morphological characters to differentiate them., Instituto de Botánica "Dr. Carlos Spegazzini", Instituto de Limnología "Dr. Raúl A. Ringuelet"

We study the «in situ» colonization of different kinds of substrata by zoosporic fungi (S.D Mastigomycotina), making weekly samplings during a month in the streams «El Zanjón» and «Las Cañas» (Ensenada, Bs. As., Argentina). In those sites we put twelve different substrata, both naturals (monocotyledon leaves, crustacean shells, Rosa sp. fruits, snake sheds and little fishes) and artificial ones (cellophane fragments, polypropylene bags, slides, and two kinds of different plastic materials). The substrata were put separately in drilled plastic bags, and left for a week to allow colonization. In both sites, we observed that Saprolegnia colonized every kind of substratum (both natural and artificial ones), while Achlya was encountered in the majority of them (little fishes, slides, cellophane fragments, pieces of X-rays, Rosa sp. fruits, and monocotyledon leaves), Dichtyuchus was observed in fishes and Rosa sp. fruits, Brevilegnia and Pythium in pieces of X-rays plate and Aphanomyces only in plastic materials. Based on these preliminary results, we can infer that there is an apparent selection of some genera for particular substrata. It’s interesting to emphasize that colonization of artificial substrata by Saprolegnia, Achlya, Brevilegnia, Pythium and Aphanomyces, might suggest the possibility of using these genera in superficial biodegradation of plastic materials., Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA)