LAUSR

The peatbogs and natural upper sections of streams in national parks in southeastern Poland represent unique study areas for research on freshwater diatom diversity. During studies conducted on diatoms in three Polish national parks, many little-known, very rare, and endangered species were noted. For most of the taxa presented in this article, especially from the Adlafia, Eunotia, and Placogeia genera, only single individuals have been observed, and only from a few localities worldwide. Moreover, this is the first presentation of SEM photodocumentation and descriptions for Eunotia minutula Grunow and Fallacia sublucidula (Hustedt) D. G. Mann. Based on both light and scanning electron microscopy, detailed descriptions of morphological characteristics, ecological notes, and new localities are presented for the following species: Adlafia langebertalotii Monnier & Ector, Caloneis undulata (Gregory) Krammer, Eunotia fennica (Hustedt) Lange-Bertalot, E. glacialifalsa Lange-Bertalot, E. groenlandica (Grunow) Nörpel-Schempp & Lange-Bertalot, E. minutula Grunow, E. neocompacta Mayama var. neocompacta, E. superpaludosa Lange-Bertalot, Fallacia sublucidula (Hustedt) D. G. Mann, Pinnularia rhombarea Krammer, P. similiformis Krammer, Placogeia gereckei (Cantonati & Lange-Bertalot) Bukhtiyarova, and Sellaphora vitabunda (Hustedt) D. G. Mann.