An improved description of Strombidium sulcatum Claparède & Lachmann, 1859 (Ciliophora) from slides of Fauré-Fremiet, and a designation of type material.

Strombidium sulcatum, the type species of the genus, is examined using silver-stained material made by Fauré-Fremiet in the 1950s and 1960s. We found that the stained specimens possessed a prominent protuberance, as previously described; the number of anterior polykinetids (APk) differed between the accounts (15 this study, 12 previous reports); although previously illustrated, no contractile vacuole was observed; and the macronuclear shape, position, and size differed from those previously reported. Our work provides the first detailed re-analysis of the silver-stained material of S. sulcatum. We use data on S. sulcatum to distinguish it from a morphologically similar species, Strombidium inclinatum. Type material for S. sulcatum has been deposited in the Natural History Museum, London.