Claparède and Lachmann, 1859
Body with prominent anterior protuberance. Oral cavity short. Contractile vacuole in mid-body on left. Equatorial kinety subequatorial, composed of dikinetids. Ventral kinety extending from equatorial kinety across posterior pole a short distance onto dorsal surface. Adoral zone continuous, composed of about 12 anterior and 7-8 ventral adoral membranelles. Single extrusome girdle behind mid-body, extrusomes inserted anterior to equatorial kinety. Subpellicular platelet layer in posterior 1/3 of body. Movement moderately fast by jerks. Size 30-60 x 25-30 µm. This characterization mainly follows Montagnes et al. (1990), who based it on Fauré-Fremiet's work and critically reviewed many previously published descriptions of this species. According to these authors, numerous populations identified as Strombidium sulcatum, e.g., by Lynn et al. (1988) and Fenchel and Jonsson (1988), belong to a different species.
Ref.: Kahl (1932), Fauré-Fremiet and Ganier (1970), Montagnes et al. (1990).