抄録
Some topics were reviewed from recent advances in the biology of alien ascidians, with special reference to the taxonomy, phylogeography and embryology (in terms of the artificial crossing and the time of natural spawning) of Ciona intestinalis species complex Sp. A to D, and the taxonomy of C. savignyi, including a short historical retrospect on the discovery of the latter species' taxonomic identity. Brief references were also made to the recent invasion of Ascidiella aspersa to the Japanese waters, the taxonomy and ecology of the notorious “D-vex”, Didemnum vexillum (once misidentified as D. pardum in Japan), the phylogeography of Styela plicata as so far unsuccessful trials to reveal its native range of geographical distribution, and that of S. clava.
