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The genus Salispina was recently described for saprotrophic estuarine oomycetes with aculeolate or spiny sporangia. The genus currently contains three species, S. intermedia, S. lobata, and S. spinosa, the latter two previously included in Halophytophthora. During a survey of mangrove-inhabiting oomycetes in the Philippines, an isolate of Salispina (USTCMS 1611), was obtained from a decaying mangrove leaf. This isolate differed from other species in the genus in a unique combination of morphological and biological characters. Phylogenetic analysis revealed it to be the sister lineage of S. lobata. Consequently, the new species name S. hoi is introduced for the isolate. In addition, Salispina spp. grouped with Sapromyces of Rhipidiales with strong support, but differs from all other known genera of the order in the weak formation of hyphal constrictions, and absence of basal thalli and a holdfast network. The new family Salispinaceae is, therefore, described to accommodate Salispina in the order Rhipidiales.

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Of the diverse lineages of the Phylum Oomycota, saprotrophic oomycetes from the salt marsh and mangrove habitats are still understudied, despite their ecological importance. Salisapiliaceae, a monophyletic and monogeneric taxon of the marine and estuarine oomycetes, was introduced to accommodate species with a protruding hyaline apical plug, small hyphal diameter and lack of vesicle formation during zoospore release. At the time of description of Salisapilia, only few species of Halophytophthora, an ecologically similar, phylogenetically heterogeneous genus from which Salisapilia was segregated, were included. In this study, a revision of the genus Salisapilia is presented, and five new combinations (S. bahamensis, S. elongata, S. epistomia, S. masteri, and S. mycoparasitica) and one new species (S. coffeyi) are proposed. Further, the species description of S. nakagirii is emended for some exceptional morphological and developmental characteristics. A key to the genus Salisapilia is provided and its generic circumscription and character evolution in cultivable Peronosporales are discussed.

Introduction Marine oomycetes are a group of fungal-like eukaryotes of the kingdom Straminipila 1. Members of this group are considered as initial colonizers of fallen senescent mangrove leaves 1 and are seen as a potentially good source of fatty acids e.g. polyunsaturated and monounsaturated that are of industrial and medical importance 2 4. Polyunsaturated fatty acids PUFAs are biological lipid derivatives which are essential in human metabolism and other biological activities 5. One application of PUFAs in the medical field is its cytotoxic and apoptotic activity against cancer

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The genus <em>Phytopythium</em> is a monophyletic taxon of the Peronosporaceae with characteristics intermediate between <em>Phytophthora</em> and <em>Pythium</em>. In the Philippines, reports of <em>Phytopythium</em> are scarce, with the mangrove-swamp-inhabiting species <em>Phytopythium kandeliae</em> being the only species recorded to date. It was the aim of the current study to investigate the diversity of <em>Phytopythium</em> in mangrove habitats in more detail. Based on culture characteristics, morphology, and molecular phylogenetic position, two new species of <em>Phytopythium</em> are described from Philippine mangroves, <em>P. leanoi</em> USTCMS 4102 and <em>P. dogmae</em> USTCMS 4101. <em>Phytopythium leanoi</em> is a species morphologically similar to <em>P. kandeliae</em>, but with the ability to develop gametangia in a homothallic fashion. The other new species, <em>P. dogmae</em>, is characterized by having a short discharge tube, semipapillate to papillate sporangia and frequently exhibiting a clustering of two sporangia per sporangiogenic hypha. With the addition of the two species described in this study, the genus <em>Phytopythium</em> has grown from around 10 to beyond 20 recognized species over the past decade, and it seems likely that several more species of this genus await discovery.

Studies on marine‐sourced fatty acids have gathered significant interest recently as an important component of aquaculture feeds and of biofuel production. Of the organisms capable of producing fatty acids, marine oomycetes are promising model organisms. One group of marine oomycetes are the Halophytophthora spp. which is known to have an important role in leaf decomposition, thereby changing the plant debris into exudates which are usable to consumers in the mangrove ecosystems. This study reports the three mangrove oomycetes isolated from Philippine mangrove forests, identified herein as Halophytophthora vesicula AK1YB2 (Aklan), H. vesicula PQ1YB3 (Quezon) and Salispina spinosa ST1YB3 (Davao del Norte). These isolates were subjected to growth analyses using varying incubation parameters (salinity level and pH), and for fatty acid production. Results revealed the presence of different fatty acids such as Arachidonic acid, Linoleic acid and Vaccenic acid when grown on V8S and PYGS media. This study is the first observation of fatty acids from S. spinosa and H. vesicula from the Philippines. Significance and Impact of the Study Tropical Philippines straddling west of the Pacific Ocean and East of South China Sea is rich in marine and estuarine oomycetes. These micro‐organisms, hitherto poorly known and unstudied in the country, play an important role in the nutritive cycle of the mangrove ecosystem. Due to the increasing demand for an alternative source of fatty acids, species of Oomycetes isolated from select mangrove forests in Luzon, Visayas and Mindanao were analysed for their fatty acid contents. Prospects for industrially‐important fatty acids make these Oomycetes all‐important to study in applied microbiology in the Philippine setting where these structurally simple micro‐organisms abound.