-(Oomycetes (Oomycota) from Maranhão State, Brazil). This study aimed at enhancing the knowledge on the diversity and distribution of Oomycetes within Parque Natural Municipal Lagoa do Sambico, in Timon municipality, Maranhão State, Brazil as well as their geographical distribution in Brazil as a whole. Of the 98 isolates, 16 were identified as Oomycetes, which belong to six families: Achlyaceae, Leptolegniellaceae s. lat., Pythiaceae s. lat., Olpidiopsidaceae s. lat., Saprolegniaceae s. str. and Verrucalvaceae. We report herewith the first records of Olpidiopsis aphanomycis Cornu and Saprolegnia luxurians (Bhargava & G.C. Srivast) R.L. Seym. for Brazil, as well as Achlya aff. diffusa J.V. Harv. ex T.W. Johnson, Achlya proliferoides Coker, Aphanomyces helicoides Minden, Aplanopsis terrestris Höhnk, Dictyuchus monosporus Leitg., Globisporangium proliferum (Cornu) P.M. Kirk, and Pythiogeton uniforme A. Lund for the State of Maranhão.

-(The genus Allomyces (Blastocladiomycota) in the State of Piauí, Brazil). Brazilian ecosystems have been intensively exploited for agricultural expansion, however, the diversity of zoosporic organisms in such biomes remains little known. Therefore, further research is required to better understand their role within these ecosystems. Studies with zoosporic fungi were carried out and 22 Allomyces isolates were obtained from soil samples collected at six municipalities from Piauí State. After identification procedures, the taxa were grouped into four species: A. anomalus R. Emers., A. arbusculus E.J. Butler, A. moniliformis Coker & Braxton, and A. neomoniliformis Indoh. A. arbusculus had the highest rate of resistant sporangia viability (10%) and the largest geographical distribution in Piauí, occurring in seven out of ten sites studied. Countrywide, they occur within 14 municipalities from three states. Greater knowledge about the geographical distribution of Allomyces in Brazil is being pioneered in the State of Piauí. Novel information regarding the diversity and occurrence, as well as taxonomic characteristics of the isolates is presented herein.

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Resumo Estudos sobre a diversidade de oomicetos foram realizados de 1998 a 2016, na Bahia, Maranhão e Piauí, e parasitas biotróficos holocárpicos zoospóricos de quitrídias, glomeromicetos e oomicetos foram identificados como Olpidiopsis achlyae, O. aphanomycis, O. fusiformis, O. karlingae, Olpidiopsis sp1 e Olpidiopsis sp2. A ocorrência de O. karlingae é novo relato para a América do Sul e de O. aphanomycis, para o Brasil. Os táxons encontrados foram descritos, ilustrados e comentados. A diversidade de termos da literatura especializada para identificação das estruturas morfológicas de Olpidiopsis foi padronizada. São propostas as sinonímias de O. braziliensis (= Pseudolpidium achlyae) com O. fusiformis e de Cornumyces karlingae com O. karlingae.