TAXONOMIC REMARKS ON PLANKTONIC PHYTOFLAGELLATES IN A HYPERTROPHIC TROPICAL LAGOON (BRAZIL)

The phototrophic flagellate flora of the Barra Lagoon (22 degrees 57' S and 42 degrees 47' W), Rio de Janeiro State, southeastern Brazil, is described. The lagoon is a shallow, oligohaline, hypertrophic ecosyst em in which Cyanophyceae, Chlorophyceae and phytoflagellates are domin ant. Between October 1990 and August 1993, weekly integrated samples w ere collected from a bay, using a plexiglass tube, 8 cm diameter and I m length. All identifications, descriptions and measurements were carr ied out on live or in Lugol-fixed material. A total of 30 taxa, belong ing to Euglenophyceae (5), Cryptophyceae (7), Raphidophyceae (1), Dino phyceae (4), Chrysophyceae (3), Prymnesiophyceae (2), Prasinophyceae ( 7) and Chlorophyceae(1) were identified. All the phytoflagellate speci es identified have been recorded previously from temperate sites. Nine of them were registered in a tropical water for the first time, sugge sting that they have much broader distributions. Gymnodinium sanguineu m, Pavlova lutheri and Pyramimonas grossii were the most frequently ob served phytoflagellates in this study. The seasonal occurrence and som e environmental requirements of selected phytoflagellates species are discussed.