135 Life History and Ecology of Trentepohliaceae (Chlorophyta) in the West of Ireland

Species of subaerial green algae of the family Trentepohliaceae are common in tropical and temperate regions. Despite nearly two centuries of investigations, several important aspects of their biology (such as life history and taxonomic relationships of some species) are still poorly understood. In western Ireland, the abundance of Trentepohliaceae is a peculiar feature of the subaerial algal vegetation. Six species are present ( Phycopeltis arundinacea, Printzina lagenifera, Trentepohlia abietina, T. aurea, T. iolithus and T. umbrina ). Life history and phenology of these were examined by extensive field and culture studies. In contrast to most other subaerial algae, the Trentepohliaceae show a generally strict substratum‐specificity in western Ireland. T. iolithus , in particular, is remarkable for its occurrence on concrete walls, where it may produce extensive dark‐red growths. Our observations suggest that general statements about the life history of Trentepohlia should be reconsidered critically. There is no evidence that in Irish populations a regular alternation of isomorphic gametophytes and sporophytes takes place; biflagellate swarmers (usually considered gametes) behave as asexual spores and reproduce the same morphological phase. No fusion of gametes was observed and a detailed examination of the literature concerning the genus shows that this phenomenon is extremely rare. A combination of studies based on different types of data (molecular data, examination of very large numbers of field samples, chromosome numbers, culture studies) is considered fundamental to any definitive clarification of the taxonomy and life history of Trentepohlia .