Abstract
The scientific name "Porella caespitans var. cordifolia" has been used by Japanese bryologists in checklists, local floras and textbooks with the author name "(Steph.) S.Hatt.". As suggested by the Missouri Botanical Garden's Tropicos database (Tropicos. org, Missouri Botanical Garden 2011), it is an illegitimate scientific name. When Porella caespitans var. cordifolia was described by Hattori (1979) as a new combination, its basionym: Madotheca cordifolia Steph. should have been indicated, since after 1 January 1953 a name is not validly published unless the basionym is clearly indicated (Code, art. 33.4). The name is validated here with the correct author citation: Porella caespitans var. cordifolia (Steph.) S.Hatt. ex T.Katag. & T.Yamag.
