Ten taxa of freshwater red algae have been observed in a survey of 62 streams and rivers within southern Ontario, Canada, over a period of 3 years. Five species are additions to the flora of Canada, Chroodactylon ramosum, Boldia erythrosiphon, Sirodotia tenuissima, Batrachospermum densum, and B. ectocarpum. In addition to these algae, Audouinella violacea, Sirodotia suecia, and Tuomeya fluviatilis are new observations within Ontario.Most of the Ontario red algae are restricted to streams or rivers with a minimum average flow rate of 10 m min−1. Audouinella violacea, B. moniliforme, and Lemanea fucina occur in a large number of streams which have a wide pH and conductivity range whereas S. tenuissima and B. ectocarpum are confined to one of the sites examined.Ultrastructural findings are reported concerning the cell organization of Boldia as well as the relationship between Batrachospermum plants and the "chantransia" stage. A key to the 10 taxa is included plus descriptions and a list of epiphytes of each alga are presented.
Morphology and molecular phylogeny of a freshwater red algae