The freshwater red algae (Batrachospermales, Rhodophyta) of Africa and Madagascar I. New species of Kumanoa, Sirodotia and the new genus Ahidranoa (Batrachospermaceae)

Our knowledge of the diversity of African freshwater red algae is rather limited. Only a few reports exist. During our field work in the last five years we frequently encountered freshwater red algae in streams in Rwanda and Madagascar. Here we describe four new species and one new genus of freshwater red algae from the Batrachospermales, based on morphological and molecular evidence: Kumanoa comperei from the Democratic Republic of the Congo and Rwanda is related to K. montagnei and K. nodiflora; Kumanoa rwandensis from Rwanda is related to K. ambigua and K. gudjewga; Sirodotia masoalensis is related to S. huillensis and S. delicatula; and the new genus and species Ahidranoa madagascariensis from Madagascar is sister to Sirodotia, Lemanea, Batrachospermum s.str. and Tuomeya. There is also evidence for the presence of Sheathia, which was recorded as yet-unidentifiable Chantransia stages. These are among the first new descriptions since 1899 from the African continent and since 1964 from Madagascar. A short history of the exploration of freshwater red algae from Africa and Madagascar is provided. All new taxa are accompanied by illustrations and observations on their ecology.