Genus Pfiesteria Steidinger et al., 1996
Monotypic genus. Multiphasic life cycle (> 20 stages) with polymorphs of bi- and triflagellate, amoeboid, and cyst stages. Life cycle stage governed by the presence of live or dead fish. Bi- and triflagellate stages typically planktonic and ephemeral; resemble gymnodinioid forms but are actually small cryptic peridinioids with a plate formula of: Po, cp, X, 4', 1a, 5'', 6c, 4s, 5''', 2'''. Flagellates with one transverse and two longitudinal flagella regarded as planozygotes. Amoeboid stages with filose to lobose forms. Cyst stages spherical to elongate with surface sculpture and/or scales. Transition forms occur between all stages. Chloroplasts present as cleptochloroplasts.
Heterotrophic and mixotrophic species; cells with large food vacuoles capable of phagocytosis. Dubbed ambush predator: feeding mode is governed by the presence or absence of fish and fish material. Estuarine species with a wide temperature and salinity tolerance.
Remarks: Other Pfiesteria-like cells have been observed from estuarine systems around the world and are suspected to be responsible for a number of major fish and shellfish kills.
Species included from this genus:
Pfiesteria piscicida Steidinger et al., 1996