Taxonomic survey of representatives of genera Cryptoglena Ehrenberg emend. Kosmala & Zakry´s, Monomorphina Mereschkowsky emend. Kosmala & Zakry´s and Phacus Dujardin (Euglenaceae, Euglenophyceae) of a reservoir in the municipality of Triunfo (30°02'15" S, 51°13'13" W), state of Rio Grande do Sul, southern Brazil. Samplings were performed at two stations during 14 consecutive months, from February 1995 to March 1996. Sixteen taxa including nine species, three varieties that are not typical of their respective species and one taxonomic forma also not typical of Phacus, two species of Monomorphina and one of Cryptoglena were identified. Phacuspseudobicarinatus is described as a new species. Phacuslongicauda (Ehrenberg) Dujardin var. longicauda, P. longicauda (Ehrenberg) Dujardin var. tortus Lemmermann, P. orbicularis Hübner, P. pleuronectes (O.F. Müller) Dujardin and P. pseudobicarinatusnov. sp. were the best represented taxa geographycally, occurring in more than 55% of samples studied. Phacuslongicauda var. longicauda and P. longicauda var. tortus were characteristic by their wide tolerance to the following environmental variables: pH, water temperature, organic matter concentration, total phosphorus and the nitrogen series (nitrite, nitrate, ammonium and total nitrogen). Phacusundulatus f. major is cited for the first time for Brazil.
Brazil; Euglenophyceae; taxonomic survey; Rio Grande do Sul State
