Calycofera gen. nov., an estuarine sister taxon to Phytopythium, Peronosporaceae

The genus Halophytophthora is a predominantly marine or estuarine genus of the oomycete family Peronosporaceae. This genus has been revealed as a highly polyphyletic assemblage of largely unrelated species. A new genus of the Peronosporaceae, Calycofera, is introduced in this manuscript to accommodate Halophytophthora operculata. Calycofera is distinct compared to Phytopythium s. str. and to Halophytophthora s. str. on the basis of sporangium morphology, sporangiogenous hyphae, and the development and release of zoospores. Phylogenetic analyses using ITS, cox2 and cox1 sequences strongly supported the establishment of this taxon. In addition, a second species of the genus was found, which is genetically more divergent from C. operculata than most sister species in the sister genus Phytopythium, and is described as C. cryptica based on diagnostic nucleotides.