Acineta tuberosa Ehrenberg, 1834 (Ciliophora: Suctoria) is recorded for the first time in the Egyptian Mediterranean waters at Port-Said, Egypt, as an epibiont of the marine filamentous green alga Cladophora sp. The body is oval or bell-shaped, 29.8 µm long. The cytoplasm almost completely or completely fills the lorica. Two actinophores are present, each bearing 4 or 5 tentacles. The tentaclular tips appear funnel-shaped because almost all tentacles of the obtained specimens function in sucking meiozoospores of the Cladophora alga. An oval macronucleus is centrally located. Stalk varies from short wedge-shaped to tubular with an average stalk length 27.8 µm. Cluster analysis approach was used to confirm that all the obtained specimens belong to A. tuberosa. The cluster analysis also showed that the length of the body and stalk contributed much to the clustering process (i.e. the most important taxonomically) followed by the mean number of tentacles per fascicle. The morphological variations within the obtained specimens proved not to be significant, if considered globally to be assigned to species other than A. tuberosa. A review of its substrate organisms and synonyms is also provided.