SYSTEMATICS AND DISTRIBUTION OF FRESH-WATER AUDOUINELLA (ACROCHAETIACEAE, RHODOPHYTA) IN BRAZIL

Forty-five Brazilian populations of freshwater Audouinella were analys ed using multivariate morphometrics. These populations were statistica lly related to seven type specimens. Five species are recognised on th e basis of qualitative (plant colour and size, basal system type and b ranch angle) and quantitative (length and diameter of vegetative cells and monosporangia) characters. A. hermannii (syn. A. violacea) is cha racterised by a reddish colour, an irregular prostrate basal system, o pen branch angles (greater than or equal to 25 degrees) and small mono sporangia (less than or equal to 15 mu m in diameter). A. macrospora ( syn. A. chalybea var. brasiliensis) is distinguished from the other Br azilian species by having a bluish colour, a basal system composed of well-developed rhizoids, narrow branch angles (< 25 degrees) and large monosporangia (greater than or equal to 15 mu m in diameter). A. meio spora is microscopic and has a reddish colour, a basal system composed of creeping filaments, narrow branch angles and small monosporangia. A. pysmaea (syn. A. leibleinii) is characterised by being bluish, havi ng an irregular prostrate basal system, narrow branch angles and small monosporangia. A, tenella is distinct from the other species by havin g a reddish colour, an irregular prostrate basal system, open branch a ngles, small monosporangia and small vegetative cells (less than or eq ual to 6 mu m in diameter). An identification key and revised descript ions and synonyms are presented for the five species. A. meiospora and A. tenella are reported for the first time for Brazil. A. macrospora and A. pygmaea were the most widespread species and occurred in tropic al and subtropical regions. A. meiospora was found at two sites in a t ropical rainforest region, whereas A. hermannii and A. tenella were fo und at only one site. Selected physical and chemical environmental dat a (temperature, specific conductance, current velocity, turbidity, pH and dissolved oxygen) are presented for most species.