Two species of Strombomonas (Euglenaceae, Euglenophyceae), S. carinata and S. ferrazi, are described and proposed as new to science. Sample units from which specimens were studied were collected from a reservoir (reservoir n. 7) located in an Environment Protection Park ("Parque de Proteção Ambiental") in the South Petrochemical Station ("Pólo Petroquímico do Sul") (29° 53'S, 51° 22'W), in Triunfo, state of Rio Grande do Sul, southern Brazil. Physical and chemical data of the water of the system from which the two species were collected are presented.
Strombomonas carinata sp. nov.; Strombomonas ferrazi sp. nov.; Euglenophyceae; Rio Grande do Sul State; Brazil