Phytopythium leanoi sp. nov. and Phytopythium dogmae sp. nov., Phytopythium species associated with mangrove leaf litter from the Philippines

The genus Phytopythium is a monophyletic taxon of the Peronosporaceae with characteristics intermediate between Phytophthora and Pythium . In the Philippines, reports of Phytopythium are scarce, with the mangrove-swamp-inhabiting species Phytopythium kandeliae being the only species recorded to date. It was the aim of the current study to investigate the diversity of Phytopythium in mangrove habitats in more detail. Based on culture characteristics, morphology, and molecular phylogenetic position, two new species of Phytopythium are described from Philippine mangroves, P. leanoi USTCMS 4102 and P. dogmae USTCMS 4101. Phytopythium leanoi is a species morphologically similar to P. kandeliae , but with the ability to develop gametangia in a homothallic fashion. The other new species, P. dogmae , 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 Phytopythium 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.