Study of terrestrial diatoms in corticolous assemblages from deciduous trees in Central Europe with descriptions of two new Luticola D.G.Mann taxa.

Although many studies have examined the algae associated with various habitats in tree trunks, the diatoms in these environments are still poorly studied. Studies of corticolous algae mainly focus on green algae and cyanobacteria, which are usually immediately visible, while diatoms are mostly overlooked or not reported. During the research, 143 species of diatoms were identified, including two new representatives of the genus Luticola: L.bryophilasp. nov. with relatively large central area and short distal raphe endings and L.confusasp. nov. characterized by the presence of small depressions on central raphe endings. Both are described herein based on light and scanning electron microscopy observations and compared to similar taxa based on literature data. Basic morphological data for almost all the diatom taxa are noted, and their habitat requirements, and photographic documentation are also presented. The present research showed that the occurrence of diatom assemblages on tree trunks is influenced by various factors like host tree species, the area where the host tree grows, and the availability of suitable microhabitats within the trunk. However, the species composition of this assemblages depends mainly on the tree species.

The influence of penguin activity on soil diatom assemblages on King George Island, Antarctica with the description of a new Luticola species.

Background: Ice-free areas in the Antarctic region are strongly limited. The presence of marine mammals and birds in those areas influence soil properties and vegetation composition. Studies on the terrestrial diatom flora in soils influenced by sea birds in the Maritime Antarctic region are scarce. Methods: Samples were collected from two transects on the western shore of the Admiralty Bay region. Light and scanning electron microscopic observations and statistical analyses were conducted to consider the impact of penguin rookeries on soil diatom assemblages. Results: The disturbance associated with the presence of penguin rookeries clearly influences the soil diatom diversity. Assemblages from areas with the highest nutrient input were characterized by a much lower diversity with only few species dominating the flora. One of recorded taxa could not be assigned to any of the known species. Therefore, based on the combination of morphological features analyzed using light and scanning electron microscopes and comparison with similar taxa in the Antarctic region and worldwide, the species is described hereby as new to science-Luticola kaweckae sp.nov. The new species is characteristic for soil habitats with strong penguin influence.

A new site for Luticola vanheurckii Van de Vijver & Levkov (Bacillariophyta) - the second record from Europe.

This paper presents the first record of Luticola vanheurckii Van de Vijver & Levkov, outside of the type locality (second record in the Europe). Authors present habitat characteristic of the species, with LM and SEM micrographs. Luticola vanheurckii was found in a small outflow of water from storm sewers in Stalowa Wola (SE Poland). Luticola vanheurckii occurred only rarely (0-5 valves per slide), in a small, shallow puddle which was supplied by the water from the outflow. This species was recorded in sediments and on plants submerged in water with a wide range of conductivity (347-22,100 µS cm-1), chloride content (64.56-6195.0 mg l-1) and sodium ions (43.04-3789.1 mg l-1). The cells observed in the examined material were slightly longer and wider than those from type locality.

Visualization of the internal structure of Didymosphenia geminata frustules using nano X-ray tomography.

For the first time, the three-dimensional (3D) internal structure of naturally produced Didymosphenia geminata frustules were nondestructively visualized at sub-100 nm resolution. The well-optimized hierarchical structures of these natural organisms provide insight that is needed to design novel, environmentally friendly functional materials. Diatoms, which are widely distributed in freshwater, seawater and wet soils, are well known for their intricate, siliceous cell walls called 'frustules'. Each type of diatom has a specific morphology with various pores, ribs, minute spines, marginal ridges and elevations. In this paper, the visualization is performed using nondestructive nano X-ray computed tomography (nano-XCT). Arbitrary cross-sections through the frustules, which can be extracted from the nano-XCT 3D data set for each direction, are validated via the destructive focused ion beam (FIB) cross-sectioning of regions of interest (ROIs) and subsequent observation by scanning electron microscopy (SEM). These 3D data are essential for understanding the functionality and potential applications of diatom cells.