This paper describes the first study of the diatom assemblages in caves in the Czech Republic. The study focused on subaeric habitats: rock faces within caves, walls at cave entrances and “lampflora” assemblages, in three cave systems, Mladeč, Javoříčko and Zbrašov, all in central Moravia. The morphological and cytological variability, ecology and life strategies of diatoms were studied in fresh samples, in Naphrax preparations, in cultures grown on agar plates and in monoclonal cultures. A total of 22 diatom species was identified, mostly aerophytic species and tolerant of low light intensities. Luticola and Diadesmis species complexes are discussed. Taxa D. gallica and L. paramutica var. binodis are new for the Czech Republic. Sexual reproduction was observed in L. mutica and Orthoseira roeseana.
This paper focuses on the morphology, taxonomy and ecology of the widespread cyanobacteria of the genus Nodularia Mertens ex Bornet & Flahault. In this study the benthic strain of N. sphaerocarpa, isolated from a sand-pit near Olomouc (Czech Republic), is compared with brackish and seawater strains. Changes in morphology and growth parameters (biomass and chlorophyll a) recorded in varying salinity gradients were studied and a 16S rRNA sequencing and AFLP analysis conducted. Morphological and ecophysiological characteristics found were in congruence with molecular data. Three major subgroups of the benthic Nodularia (N. sphaerocarpa, N. moravica and N. harveyana) were found using the polyphasic approach. The results of both the molecular and morphological study clearly separated N. moravica and N. sphaerocarpa, as freshwater species preferring a low salinity and the N. harveyana strains originating from a marine environment preferring a high salinity.
Monoclonal cultures of the aerophytic cave diatom Luticola dismutica were studied and its frustule morphology, cytology and reproduction recorded. Luticola dismutica is a laterally asymmetrical, monoplastidic pennate diatom with imposed chloroplast division and nuclear behaviour of type 1.A sensu Mann & Stickle. Clones of L. dismutica decreased in cell size in culture until they have reached the sexual size range. Homothallic sexual reproduction and auxosporulation (type IB1a auxosporulation sensu Geitler) were induced in four sexualized clones. Gametangia paired via the girdle, two isogametes were formed per gametangium and hence two zygotes were produced per pair of gametangia. No surviving superfluous nuclei were observed in the gamete and zygote stages and no unfused haploid nuclei were seen in the auxospore stage; zygotes and expanded auxospores had only one nucleus. Auxospores expanded perpendicular to the apical axis of gametangia. Expanded auxospores and initial cells had a swollen central part, the linear-lanceolate outline shape of the vegetative valves was restored during the first divisions of the post-initial cells. Initial cells left the perizonium by a route unique to pennate diatoms, through a transverse rupture of the perizonium. The key cytological and reproductive characteristics reviewed in this paper indicate, that Luticola is more closely related to Placoneis and Dickieia, than to Navicula sensu stricto.