Several filamentous oomycete species of the genus Halophytophthora have recently been described
from marine environments, mostly from subtropical and tropical ecosystems. During a survey of oomycetes from
leaf litter of Spartina alterniflora in salt marshes of southeastern Georgia, isolates of four taxa were recovered that
bore similarity to some members of Halophytophthora but were highly divergent from isolates of Halophytophthora
s.str. based on a combined sequence analysis of two nuclear loci. In phylogenetic analyses, these isolates were
placed basal to a monophyletic group comprised of Pythium of the Pythiaceae and the Peronosporaceae. Sequence
and morphology of these taxa diverged from the type species Halophytophthora vesicula, which was placed within
the Peronosporaceae with maximum support. As a consequence a new family, the Salisapiliaceae, and a new genus,
Salisapilia, are described to accommodate the newly discovered species, along with one species previously
classified within Halophytophthora. Morphological features that separate these taxa from Halophytophthora are
a smaller hyphal diameter, oospore production, lack of vesicle formation during sporulation, and a plug of hyaline
material at the sporangial apex that is displaced during zoospore release. Our findings offer a first glance at the
presumably much higher diversity of oomycetes in estuarine environments, of which ecological significance requires
further exploration.