Limnetica 36

Environmental assessments and palaeoreconstructions can take advantage of the high diatom diversity present in mountain lakes. There are only a few studies dealing with the diatom flora of the Pyrenees and research on species taxonomy, distribution and ecology are still at an initial stage. With the aim of updating the list of species present and providing iconographic information for harmonising past and future studies, we report 549 taxa from a survey of 83 lakes across the geographical extent of the Pyrenean lakes comprising a broad range of environmental conditions and in the sedimentary record of the Burg lake. This study is a first step in the development of a comprehensive on-line atlas of Pyrenean diatoms including species occurrence, distribution and ecology (www.diatopyr.com). Samples were collected both from littoral epilithic substrates and the top of the sediment in the deepest zone of the lake. Additionally, we include also taxa that were present in the Late Glacial and Holocene sedimentary records of the Burg palaeolake, which were not found in the survey. The genera including more diversity were Pinnularia, Gomphonema, Eunotia and Nitzschia. About 25% of taxa remain to be determined at fine taxonomic resolution, many of them are likely to be species or varieties not described yet.