Phalacroma rotundatum
Diagnosis
Diagnoses_Genus: Phalacroma (Stein 1883, emended Jensen and Duagbjerg 2009). Small to medium sized cells. Cell outline is typically circular to ellipsoid and can be tapered posteriorly. Cells are more or less laterally depressed. Epitheca is large but <¼ of the cell length. It is visible above the cingular lists, and flattened to convex in outline. Cingular lists are narrow and horizontal and can possess ribs. Left sulcal list typically widens posteriorly and always possesses three distinct ribs. Thecal ornamentation is of different types, from smooth with scattered pores to deep and strongly areolated. Cytoplasm is colorless, pink or yellow-brown. Chloroplasts of haptophyte origin are observed in a few species.
Etymology
Adjective (Latin), almost circular, with length breadth ratio of about 6 to 5 (Stearn 1973).
Type species
The type species (lectotype) of the genus Phalacroma is Phalacroma porodictyum Stein.
Type illustration / Type locality / Type specimen
Type locality: North Sea: Glesnesholm, Norway (Faust & Gulledge 2002: 32).
Ecology
Substrate: planktonic
Sociability: solitary
Salinity: marine
pH: neutral
Feeding: Photosynthetic
Life cycle
Phases_alternance: haplontic
Generation: <1 month
Reproduction_mode: asexual_binary