Dinaric karst intermittent rivers harbour some rare mayflies (Insecta, Ephemeroptera)

While investigating the aquatic macroinvertebrate fauna of four intermittent Dinaric karst rivers in Croatia, we confirmed or recorded new distribution data and ecological features for several mayfly species rare in Croatian freshwater habitats: Nigrobaetis niger (Linnaeus, 1761), Procloeon pennulatum (Eaton, 1870) and Paraleptophlebia werneri Ulmer, 1920. To our knowledge, this is the first record of N. niger in intermittent lotic habitats. We discuss their substrate preferences in the studied habitats as well as their relationships with measured physico-chemical water parameters. The newly obtained results confirm that our knowledge about Croatian mayfly fauna and species ecological requirements in intermittent Mediterranean rivers is still incomplete and is increasing with systematic studies.