Seventeen specific and infraspecific taxa of the genus Strombomonas Defl. are described as a result of a study in lentic systems of Casamento Lake (30º03'-30º34' S and 50º25'-50º47' W) and near the Tapes Butiazal (30º23'-30º38' S and 51º16'-51º29' W), coastal zone of Rio Grande do Sul state, with a subtropical climate. The qualitative samples were collected in autumn (May and June) and spring (October) 2003. Four taxa are new records for the state: Strombomonas conspersa (Pascher) Tell & Conf., S. girardiana (Playf.) Defl. var. triondulata Tell & Zaloc., S. maxima (Skv.) Defl. var. oviformis Shi and S. tuberosa (Skv.) Defl. var. conspersa (Skv.) Defl.; new records for South America are: S. maxima var. oviformis and S. tuberosa var. conspersa. Strombomonas scabra var. ovata f. minor Tell & Conf. and S. verrucosa (Daday) Defl. were the only taxa found in both areas. The range of environmental variables for taxa of Strombomonas is registered on the Coastal Plains and compared to other aquatic environments of the state.
Euglenophyta; taxonomy; geographical distribution; environmental variables
