Jana Veselá

Pseudocryptic diversity versus cosmopolitanism in diatoms: a case study on Navicula cryptocephala Kütz. (Bacillariophyceae) and morphologically similar taxa.

Despite the significance of diatoms in biomonitoring, many aspects of their biodiversity and geographical distribution are poorly understood. Recent evidence from molecular data has shown that traditional cosmopolitan and euryvalent morphospecies are often heterogeneous, containing cryptic or pseudo-cryptic species. It is important to establish whether these more finely differentiated species are also cosmopolitan or show restricted distributions. According to the standard freshwater diatom floras, Navicula cryptocephala and morphologically similar species (N. veneta, N. trivialis, N. gregaria and N. cryptotenella) are common, cosmopolitan freshwater pennate diatoms. Although allopatric and even sympatric populations of N. cryptocephala are extremely similar morphologically, they have previously been found to be highly polymorphic with respect to reproductive and nuclear characteristics; however, molecular data supporting the existence of cryptic diversity were lacking. Phylogenetic analyses (LSU rDNA, ITS of the rRNA operon) of 52 strains of N. cryptocephala-like diatoms confirmed the existence of genetically distinct lineages within N. cryptocephala, and revealed a close relationship between N. trivialis and N. cryptocephala. Cytological, reproductive and morphological variation, investigated by means of landmark-based geometric morphometrics, were in congruence with molecular data. Two pseudo-cryptic species within N. cryptocephala coexist sympatrically and are widely distributed, occurring in both European and Australian lakes.

Leptochlorella corticola gen. et sp. nov. and Kalinella apyrenoidosa sp. nov.: two novel Chlorella-like green microalgae (Trebouxiophyceae, Chlorophyta) from subaerial habitats

The diversity of green microalgae in subaerial habitats remains largely unexplored and a number of new genus- and species-level lineages have been discovered recently. The traditional green algal genus, Chlorella, which accommodated coccoid unicellular green algal species with globular to oval cells, reproducing entirely by autospores, has been found to be polyphyletic. In this study, we provide a detailed characterization of two strains of microalgae isolated from tree bark in the Mediterranean. These algae share the general Chlorella-like morphology and their 18S rRNA and rbcL gene sequences place them in the Trebouxiophyceae. Strain CAUP H8401 forms an independent trebouxiophycean lineage, together with three previously published 18S rRNA gene environmental sequences of undescribed microalgae, which were retrieved from profoundly different habitats. In contrast, strain CAUP H7902 is related to Kalinella bambusicola in the Watanabea clade of the Trebouxiophyceae on the basis of its 18S rRNA gene sequence. This relationship is also supported by the rbcL gene sequence, acquired from the type strain of K. bambusicola. The investigated strains are described as representatives of a novel species in a new genus, Leptochlorella corticola gen. et sp. nov., and a novel species, Kalinella apyrenoidosa sp. nov., according to the International Code of Nomenclature for Algae, Fungi and Plants.

Epiphytic lichen diversity in central European oak forests: Assessment of the effects of natural environmental factors and human influences

We investigated lichen diversity in temperate oak forests using standardized protocols. Forty-eight sites were sampled in the Czech Republic, Slovakia and Hungary. The effects of natural environmental predictors and human influences on lichen diversity (lichen diversity value, species richness) were analysed by means of correlation tests. We found that lichen diversity responded differently to environmental predictors between two regions with different human impact. In the industrial region, air pollution was the strongest factor. In the agricultural to highly forested regions, lichen diversity was strongly influenced by forest age and forest fragmentation. We found that several natural factors can in some cases obscure the effect of human influences. Thus, factors of natural gradient must be considered (both statistically and interpretively) when studying human impact on lichen diversity.

Parachloroidium gen. nov. (Trebouxiophyceae, Chlorophyta), a novel genus of coccoid green algae from subaerial corticolous biofilms

Neustupa J., Němcová Y., Veselá J., Steinová J. and Škaloud P. 2013. Parachloroidium gen. nov. (Trebouxiophyceae, Chlorophyta), a novel genus of coccoid green algae from subaerial corticolous biofilms. Phycologia 52: 411–421. DOI: 10.2216/13–142.1 The Watanabea clade of the Trebouxiophyceae included mostly unicellular coccoid microalgae that thrived in various terrestrial microhabitats. The diversity of these morphologically uniform microalgae was little known, and several new genus-level lineages had recently been described on the basis of molecular data. In this study, we provided a taxonomic description of a new trebouxiophycean genus, Parachloroidium, found in the Mediterranean in corticolous phototrophic biofilms. Their simple chlorelloid morphology did not unambiguously distinguish the Parachloroidium strains from other similar green algae. However, ultrastructural characteristics and molecular phylogenetic analyses based on the 18S ribosomal (r)DNA, internal transcribed spacer region (ITS) and the chloroplast ribulose-bisphosphate carboxylase gene sequences provided a basis for the discrimination of Parachloroidium from related genera of the Watanabea clade. The four strains investigated formed two species, P. laureanum and P. lobatum, which differed in plastid morphology and in ITS and 18S rDNA sequences. All four strains were characterized by globular or ellipsoidal cell shapes, single parietal plastids and asexual reproduction by autospores. Their plastids lacked typical pyrenoids; however, plastids included peculiar thylakoid-free regions of irregular shape. On the basis of accumulating molecular data, we concluded that the Watanabea clade was a diverse phylogenetic lineage within the subaerial chlorelloid green algae.

THE DIATOM FLORA OF EPHEMERAL HEADWATER STREAMS IN THE ELBSANDSTEINGEBIRGE REGION OF THE CZECH REPUBLIC

The diatom flora of 15 headwater streams in the Elbsandsteingebirge region of the Czech Republic was studied. This region is dominated by sandstone, but a few areas have a mixed geology with some combination of sandstone, limestone, and granite. Diatoms were collected from a mixture of substrates whenever available, including stone, wood, bryophyte, and sediment. A total of 307 diatom taxa were observed, including one species new to science, Chamaepinnularia rexii. Taxa particularly characteristic for the region, or lacking previous indicator status, or rare or otherwise interesting are illustrated and discussed. Abundance weighted means for both pH and conductivity are reported for all taxa which occurred in more than four samples.

Ecological variation within traditional diatom morphospecies: diversity of Frustulia rhomboides sensu lato (Bacillariophyceae) in European freshwater habitats

Veselá J., Urbánková P., Černá K. and Neustupa J. 2012. Ecological variation within traditional diatom morphospecies: diversity of Frustulia rhomboides sensu lato (Bacillariophyceae) in European freshwater habitats. Phycologia 51: 552–561. DOI: 10.2116/11-101.1 More than 300 strains of Frustulia rhomboides sensu lato were isolated from populations across Europe to estimate its molecular diversity and geographic distribution in oligotrophic freshwater habitats. Phylogenetic analyses, based on partial large subunit (LSU) rDNA sequences, revealed six lineages that did not fully correspond with the separation of F. rhomboides into traditional varieties. Although four closely related lineages showed substantial overlaps in morphology, the characteristic morphological features could be determined using morphometric techniques. The phylogenetic lineages of F. rhomboides showed different patterns of distribution among regions. Sequence frequencies within samples from different habitats indicated that distribution of the common lineages most likely reflected their different ecological preferences rather than dispersal constraints.

Differential cell size structure of desmids and diatoms in the phytobenthos of peatlands

The mean cell sizes of microalgae vary in relation to the abiotic factors, such as nutrients, temperature, or water transparency. This study focused on the community cell size of desmids and diatoms, two dominant groups of the peatland phytobenthos. Forty samples from various temperate European peatlands were investigated. The species composition and the species richness were controlled mainly by the pH levels. Purely spatial factors also significantly affected the species composition. Interestingly, diatoms were more strongly geographically restricted than desmids. The spatial control of the species composition was limited mostly to the large taxa, which indicated that dispersal limitation may be an important structuring factor for phytobenthos at a regional scale. The mean cell sizes of desmids were related to the ombro-minerotrophic gradient, pH, and Ca concentration. Acidic, ombrotrophic bogs typically contained small cells, whereas minerotrophic fens had larger desmids. By contrast, the diatom size structure did not depend on the ombro-minerotrophic gradient. Thus, the cell sizes of desmids in peatlands may be used as a proxy for important environmental processes, such as transition from minerotrophy to ombrotrophy, or acidification, whereas diatoms did not primarily respond to these processes and their size structure is driven by different factors, such as conductivity.

Species concept and morphological differentiation of strains traditionally assigned to Micrasterias truncata

The morphological and molecular differentiation of the Micrasterias truncata (Corda) ex Bréb species complex was investigated. In total, 17 strains traditionally assigned to M. truncata were isolated from different European localities (Czech Republic, southwest France, Ireland), and obtained from public culture collections. In addition, strains of the morphologically similar species, M. decemdentata (Nägeli) W. Archer and M. zeylanica F. E. Fritsch, were also included. Molecular phylogenetic analysis based on trnGucc intron sequences revealed five well supported clades. Two Australian strains assigned to M. truncata var. pusilla G. S. West formed a lineage sister to M. zeylanica. This was evident from a concatenated phylogeny based on small subunit rDNA and trnGucc intron sequences. The isolated position of these strains was also illustrated by parallel landmark‐based geometric morphometric analysis of cell shapes. The strains NIES 783 and NIES 784 probably represent a separate species. Particular analysis, including additional strains, is needed to resolve the relationship inside this lineage. The second phylogenetic lineage, containing two strains of M. truncata var. semiradiata (Kützing) Wolle, was also different from other strains on the basis of morphometric data. We suggest recognizing this variety as a separate species, Micrasterias semiradiata L.A. Brébisson ex F. T. Kützing. The remaining three clades formed a firmly supported group of the ‘core’M. truncata recognized by both molecular markers. However, neither any morphological, morphometric, nor geographical pattern was detected among members of these three clades. This pattern could be caused by a relatively recent origin of these lineages that may represent a sympatric, truly cryptic species. Strains attributable to traditional morphologically defined variety M. truncata var. neodamensis were nested within the ‘core’M. truncata.

Spatial heterogeneity and ecology of algal communities in an ephemeral sandstone stream in the Bohemian Switzerland National Park, Czech Republic

Spatial patterns and biodiversity of algae assemblages, and the effect of environmental factors on species composition were studied in an ephemeral pristine stream. Samples were taken along a longitudinal stream transect beginning at the source. At each sampling site, different types of substrates were collected and water chemistry investigated. A total of 109 infrageneric algal taxa were identified with diatoms being the most diverse group (85 taxa). Characteristic diatom species included: Chamaepinnularia soehrensis, Diadesmis laevissima, D. paracontenta, Eunotia exigua agg., E. incisa, E. ursamaioris, Fragilariforma virescens, Microcostatus krasskei, Pinnularia silvatica agg., and P. subcapitata agg. In addition, green algae of the Chlococcaceae agg., and Klebsormidium flaccidum were also abundant. Composition of algal assemblages were primarily influenced by the type of substratum (20.5% variance explained, p = 0.001) and by the spatial distance from the stream origin (3.0%, p < 0.05). Variation in species composition explained by conductivity, pH, temperature and nitrogen was relatively low (10.1%).

The Algal Flora of Acadia National Park, Maine

Abstract The inland algal flora of Acadia National Park was studied based on over 200 samples from 119 localities. A total of 160 algal genera were found, representing 12 algal phyla. Among these were 140 new generic records for the Park. The most frequently encountered taxa were desmids and diatoms, and the genera and species in these groups were acidophilous, reflecting the low pH of the ponds, lakes, and streams of the Park. Ponds and streams were the most heavily sampled habitats in the Park, and coincidentally had the highest diversity (103 and 91 genera, respectively). Based on other similar studies, we estimate that the Park likely contains as many as 1000 algal species within its boundaries, indicating that the diversity is exceptionally high for an area of this size.