By 1968, the authoress pointed out the first report concerning to the presence of the genus Synchaeta in Brazil, notifying S. neapolitana. At present, in 1972, she gives the first information of the species S. tremula with its new variety digitata distinguished by principal characteristics as follows: Trophii with deeply digitate, palmate and finger-shaped uncus. This variety was found at Enseada de Inhaúma, Guanabara Bay, into waters under mesohaline conditions, and A-mesosaprobic pollution. The present article shows a key of species to separate S. tremula var. digitata from others.