Abstract: The effects of desiccation on photochemical processes and nitrogenase activity were evaluated in Nostoc commune s.l. colonies in situ from a wet thufur meadow at Petuniabukta, Billefjorden, Central Svalbard, during the 2009 arctic summer. The colonies were collected in the fully hydrated state, and were subjected to slow desiccation at ambient temperatures (5 - 8°C) and low light (30 - 80 μmol.m-2.s-1). For each colony the weight, area, photochemical performance, and nitrogenase activity were determined at the beginning, as well as on every day during the first four days of the experiment; thereafter, on every second day until desiccation was complete. The photochemical performance was evaluated from variable chlorophyll fluorescence parameters (FV/FM, ΦPSII , qP, and NPQ), and the nitrogenase activity was estimated by an acetylene-ethylene reduction assay. A significant decrease in the photochemically active area was recorded from the third day, when the colony had lost approximately 40% of its original weight indicating some changes in the extracellular matrix, and stopped on the 14th to 18th day. No effects of the desiccation on the main photochemical parameters (FV/FM, ΦPSII, qP) were observed up to the sixth to eighth days of desiccation. Slightly lower values of FV/FM and ΦPSII recorded in fully-hydrated colonies could be caused by impaired diffusion of CO2 into cells. The steep reduction of photochemical activity occurred between the eighth and tenth day of the experiment, when the colony had lost approximately 80% of its fully-hydrated weight. The nitrogenase activity was highest on the first day, probably due to improved diffusion of N2 into cells, then declined, but was detectable until the sixth day of the experiment. Since Nostoc commune s.l. colonies were capable of photosynthesis and nitrogen fixation to the level of ca. 60% of its fully-hydrated weight, even partly-hydrated colonies contribute substantially to carbon and nitrogen cycling in the High Arctic wet meadow tundra ecosystem.

Abstract: Twenty nine Phormidium-like strains, obtained from different culture collections, isolated from different habitats and geographical localities were analyzed morphologically as well as using HPLC, spectrophotometry, RAPD markers (random amplified polymorphic DNA) and RFLP (restriction fragment length polymorphism) of 16S rRNA sequences. On the base of cell width, degree of constriction between adjacent cells and cell form three distinct groups were recognized. Group I consisted of strains with the cell width less than 1.5μm, elongated with strong constrictions; group II contained majority strains with the cell width between 1.5 and 2.5μm, isodiametric and only slight constrictions and the cross walls; group III contained strains with cells more than 2.5μm wide and disc-shaped, without constrictions. In strains investigated here, only eight major carotenoids and three mycosporines occurred. Phormidium-like strains showed remarkable differences in the carotenoid composition. Four main combinations in occurrence of different carotenoids were found. The presence of zeaxanthin and β-carotene was common to all studied strains. Molecular analysis did not show any correlation between pigment composition of strains and their phylogenetic relationship. However, genetically similar strains were similar in cell size and shape. The observed morphotypic traits by themselves appear to be insufficient for classification because some distant groups also showed similar features. Our results support the notion that the genus Phormidium sensu Gomont represents a phylogenetically polyphyletic group. Furthermore, our data have demonstrated the need for a comprehensive revision of the taxonomy of this group. Results of our studies show that the taxonomic problems of the filamentous cyanobacteria with narrow trichomes can be solved only with the application of modern, combined criteria.

Abstract: Scytonematopsis Kiseleva is a poorly known cyanobacterial genus with a widespread, mostly tropical distribution. A new species, S. contorta, is described from the Hawaiian Island of Oahu based on morphological and molecular evidence. The new species was found growing on rock in damp aerial habitats proximal to streams and waterfalls. It differs in several regards to the other 14 species, in particular in its pronounced ability to produce a spirally contorted trichome within a single filament. The phylogenetic placement of the genus is uncertain. It is associated with both Rivularia and Calothrix species in the Rivulariaceae, and is distant from the Scytonemataceae, where it has traditionally been placed. However, the relationship of these taxa is unresolved, as there was very little support for the deeper nodes of the phylogeny.

Abstract: The present study focuses on a description of the biodiversity of subaerial phototrophic biofilms occurring on archaeological surfaces in Maltese hypogean environments, namely St Paul's, St Agatha's and Abbatija tad-Dejr Catacombs, all situated in Rabat and the ancient Ħal Saflieni Hypogeum at Paola, Malta. Direct observation of the biofilms, carried out using light (LM), epifluorescent and confocal laser scanning microscopy (CLSM), allowed the description of the major cyanobacterial and microalgal taxa, and also the associated heterotrophic microorganisms, mainly actinobacteria. Some biofilm microorganisms were able to grow in culture and this allowed the isolation of cyanobacterial, microalgal and chemoorganotrophic bacterial strains. Thylakoid arrangement and cell division were examined using transmission electron microscopy (TEM). The cytomorphology of isolated microorganisms was described. The undisputed phototrophic protagonists in these subaerial biofilms of Maltese hypogean environments were the non-heterocytous (Oscillatorialean) cyanobacteria. In order to increase the limited data available for Leptolyngbya spp. from aerophytic epilithic biofilms in catacombs, the 16S rRNA genes of isolated Leptolyngbya strains were sequenced and compared with those obtained for related strains. Phylogenetic trees of cyanobacterial 16S rRNA sequences were constructed using parsimony and Bayesian analyses. Microorganisms forming biofilms in Maltese hypogea were found to be similar, both cytomorphologically and genetically, to those colonising lithic surfaces of caves and catacombs in other Mediterranean countries.

Abstract: The Uruguay River is the second most important river in the Rio de la Plata Basin. Taxonomical composition, abundance and distribution of cyanobacteria collected at nine sampling stations in the Lower Uruguay River (Uruguay) were analyzed seasonally from 2006 to 2009. A total of 24 taxa were identified, including 13 Chroococcales, 4 Oscillatoriales and 7 Nostocales species. The genera Dolichospermum and Microcystis presented the highest number of species among the planktic water bloom-forming cyanobacteria. The highest densities of cyanobacteria were recorded in summer during a bloom, with 6.2×106 cells.ml-1, and the most abundant species were Microcystis aeruginosa and Dolichospermum cf. pseudocompactum. In this case, the toxicity analyses by HPLC did not indicate the presence of microcystin-LR. Phytoplankton growth in the Uruguay River was found not to be nutrient-limited. The high correlation of cyanobacteria densities with nitrogen and phosphorous compounds is directly related to changes in flow. Cyanobacteria densities increased with summer high temperatures in low flow conditions. The ANOSIM analysis showed no significant differences between zones and sampling sites, but there were temporal significant differences in relation to seasonal samplings. Radiocystis fernandoi Komarek et Komarkova-Legnerova was recorded for the first time in Uruguay and Dolichospermum cf. pseudocompactum (Watanabe) Wacklin et al. was recorded for the first time in South America.

Abstract: Anabaenopsis elenkinii Miller forms bloom in the alkaline shallow lakes of the Brazilian Pantanal. The A. elenkinii CCIBT1059 strain was isolated from one of these alkaline lakes and the experiments were made in growth chamber during 30 days, under modified medium BG-11 (3 % NaNO 3 ), temperature 25 oC, photoperiod 12-12 light-dark cycle and irradiance of 80-100 µmol photons m -2 s -1 at three different pH values: 7.0, 9.5 and 10.5. In relation to growth rate and cell yield the higher values were observed at pH 10.5. Morphologically, the longest trichomes were found at pH 7 (maximum 45 cells) in comparison with pH 9.5 (maximum 32 cells) and pH 10.5 (maximum 23 cells). The occurrence of heterocytes was observed in all treatments, but akinetes were never formed. The morphometric variability within each treatment between exponential and stationary growth was clearly higher than the variability among different treatments in most cases. Our results indicate that A. elenkinii is typical of alkaline systems and also that in lower pH values the growth limitation can occur in terms of number of cells and biomass. This study represents the first experimental evidence of the effects of pH on growth rate, cell yield and morphometric variability of A. elenkinii.

Abstract: The ability of the small ribosomal subunit (16S) rRNA to infer fine-scale phylogenetic relationships is, in principal, impaired by the presence of multiple and variable gene copies within the same genome. This study investigated the extent of intra-genomic 16S rRNA gene heterogeneity in cyanobacteria. Using bioinformatics, all available sequenced cyanobacterial genomes were screened for microheterogeneity between their paralogous ribosomal genes. As a result, cyanobacteria were found to commonly contain multiple ribosomal operons and the numbers of copies were relatively proportional to genome size. Moreover, intra-genomic paralogous 16S rRNA gene copies often contain point-mutations that were validated by secondary structure modeling to be true point mutations rather than sequencing errors. Although microheterogeneity between paralogous 16S rRNA genes is relatively common in cyanobacterial genomes, the degree of sequence divergence is relatively low. We conclude that cyanobacterial intra-genomic 16S rRNA gene heterogeneity generally has a relatively small impact on species delineation and inference of evolutionary histories of cyanobacteria.

Abstract: Three new strains of members of the family Oocystaceae collected in inland waters of Africa were studied microscopically and by molecular phylogeny. The new genus Elongatocystis was decribed, and the new combination Elongatocystis ecballocystiformis was proposed. The phylogenetic position of Oocystidium sp., and Quadricoccus ellipticus within the family was shown. The SSU rRNA phylogeny of Oocystaceae recovered a need for further studies to display the generic and species concept in this monophyletic group of green algae. The essential research steps were discussed.

Abstract: The study of genome size variation in microalgae lags behind that of comparable research in higher plants and seaweeds. This situation is essentially caused by: (1) difficulties in obtaining sufficient biomass for experiments; (2) problems with protoplast isolation due to cell-wall heterogeneity and complexity; and (3) the absence of suitable standards for routine measurements. We propose a multi-step protocol that leads to the quantification of DNA content in desmids using flow cytometry. We present detailed culture conditions, the minimal biomass necessary for three repetitive measurements, a method to isolate protoplasts and selection of suitable standards. Our protocol, which is mainly based on studies with higher plants and commercially available enzyme mixtures, is useful in Streptophyta, especially members of the Zygnematophyceae, because of their close phylogenetic relationship to higher plants, in particular the similarity of their cell wall organization. Moreover, the suggested protocol also works for some Chlorophyta (Chloroidium ellipsoideum, Tetraselmis subcordiformis) and Heterokontophyta (Tribonema vulgare). We suggest and characterize a new standard for flow cytometry of microalgae (Micrasterias pinnatifida). Modification of the enzyme mixture is probably necessary for microalgae whose cell walls are surrounded by a mucilaginous envelope (Planktosphaeria), those that contain alganan (Chlorella), monads with a pellicle or chlamys (Euglena, Chlamydomonas). While we did not anticipate any success with diatoms (Pinnularia), because of their silica frustules, the enzyme mixture also failed for some other green microalgae (Xanthidium, Kentrosphaera, Stigeoclonium, Trentepohlia and Pseudendoclonium).

Abstract: Solar salterns can be found in many tropical and subtropical regions throughout the world, however, nothing is known from these habitats in Southeast Asia. The Petchaburi solar salterns are located in Petchaburi Province, middle part of Thailand. These areas can be defined as hypersaline biotopes where, in salt-producing times, salinity increases by more than 10 times that of seawater. The annual salinity gradient of these areas ranges from 0 - 35 ppt. in the non salt-producing period and gradually elevates from more than 35 ppt. up to saturation in the salt producing period, when salt crystals are formed. The cyanobacterial samples were collected from four ponds of the Petchaburi saltern during the salt producing period (November - December 2009), when the range of salinity was from 90 - 250 ppt. pH values of soil samples ranged from 7.9 - 8.1 and conductivity from 164 - 350 dS/m. Other physico-chemical parameters were analyzed in the soil samples as well. Cyanobacterial mats and their filaments predominated among the diatoms. Sixteen species of cyanobacteria were found. Dominant species were Spirulina subsalsa, Coleofasciculus cf. chthonoplastes and Oscillatoria lloydiana. Most of the species found in this study have not yet been reported in Thailand. Species, which did not correspond to any described taxa in scientific literature (new species or unknown modifications) are designated by "cf." or "sp.".

Abstract: Umezakia natans M.Watan. was described by Dr. M. Watanabe in 1987 as a new species in the family of Stigonemataceae, following the rules of the Botanical Code. According to the original description, this planktonic filamentous species grows well in a growth media with pH being 7 to 9, and with a smaller proportion of sea water. Both heterocytes and akinetes were observed, as well as true branches developing perpendicular to the original trichomes in cultures older than one month. Watanabe concluded that Umezakia was a monotypic and only planktonic genus belonging to the family of Stigonemataceae. Unfortunately, the type culture has been lost. In 2008, we successfully isolated a new strain of Umezakia natans from a sample collected from Lake Suga. This lake is situated very close to the type locality, Lake Mikata in Fukui Prefecture, Japan. We examined the morphology of this U. natans strain, and conducted a DNA analysis using 16S rDNA regions. Morphological characters of the newly isolated strain were in a good agreement with the original description of U. natans. Furthermore, results of the DNA analysis showed that U. natans appeared in a cluster containing Aphanizomenon ovalisporum and Anabaena bergii. Therefore we conclude that Umezakia natans belongs to the family of Nostocaceae, not to Stigonemataceae.

Abstract: Venezuelan Table Mountains (tepuis) are among world's most unique ecological systems and have been shown to have high incidence of endemics. The top of Roraima, the highest Venezuelan tepui, represents an isolated enclave of species without any contact with the surrounding landscape. Daily precipitation enables algae and cyanobacteria to cover the otherwise bare substrate surfaces on the summit in form of a black biofilm. In the present study, 139 samples collected over 4 years from various biotopes (vertical and horizontal moist rock walls, small rock pools, peat bogs, and small streams and waterfalls) were collected and examined for algal diversity and species composition. A very diverse algal flora was recognized in the habitats of the top of Mt. Roraima; 96 Bacillariophyceae, 44 Cyanobacteria including two species new to science, 37 Desmidiales, 5 Zygnematales, 6 Chlorophyta, 1 Klebsormidiales, 1 Rhodophyta, 1 Dinophyta, and 1 Euglenophyta were identified. Crucial part of the total biomass consisted of Cyanobacteria; other significantly represented groups were Zygnematales and Desmidiales. Investigated biotope types were demonstrated to have different composition of algal communities.

Abstract: This paper provides information on the origin and the etymology of the names of genera of Cyanophyta/Cyanobacteria in current use and on the way new names are formed under the provisions of the International Code of Botanical Nomenclature and the International Code of Nomenclature of Prokaryotes. Special emphasis is placed on the differences between the two Codes that should be taken into account when creating new names compatible both with the botanical and with the bacteriological nomenclature system, to support the ongoing efforts to harmonize the nomenclature of the Cyanophyta/Cyanobacteria under the two Codes.

Abstract: As part of a study on the diatom flora of the Gokyo Valley, Everest National Park, Nepal, eleven species of Cymbopleura (Bacillariophyta), including two new species, Cymbopleura gokyoensis juttner et V an de V ij V er sp. nov. and Cymbopleura emoda juttner et V an de V ij V er sp. nov., were investigated using light and electron microscopy. Some taxa could not be identified with certainty using the currently available literature due to small differences in valve dimensions, raphe structure and striation patterns. It remains unclear whether they represent new species or whether the original descriptions should be emended to include the populations from Nepal.

Abstract: For the first time the genus Wollea Bornet et Flahault was recorded in Eastern Siberia (Yenissei River, Karskoe See Basin) and isolated to monoclonal axenic strain ACCS 045. The strain was characterized by a combination of morphological and molecular approaches. It shares the diacritical features of the type-species W. saccata (Wolle) Bornet et Flahault and W. bharadwajae R.N. Singh such as macroscopic gelatinous colonies, tube-like, trichomes more or less straight or slightly curved, sheaths around trichomes are absent, heterocytes intercalary, and paraheterocytic akinete development at both sides of heteocytes in short series. A morphological comparison shows that it differs from W. saccata in the form of colonies being saccule, the form of vegetative cells and the heterocytes being barrel-shaped, the form of terminal cells being conical-rounded, and from W. bharadwajae in the form of akinetes being cylindrical or ellipsoid. The first available 16S rRNA gene sequence of Wollea appeared poorly related to other cyanobacterial sequences. According to the traditional classification systems based on morphological and ecological observations genus Wollea appears closest to Anabaena and Nostoc. However, the phylogenetic placement of Wollea based on 16S rRNA gene sequence was distant from Nostoc and the most closely related to taxa in benthic Anabaena, Sphaerospermopsis, Cylindrospermopsis, and Raphidiopsis.

Abstract: Arid mangroves constitute a particular biotope, with very extreme variations in ecological conditions, mainly temperature and salinity, condition that demand specific adaptations to successfully inhabit this ecosystem. Cyanoprokaryotes have not been well studied in Mexican coasts and this is the first study that contributes to the knowledge of the biodiversity of this group in an arid mangrove in Zacatecas estuary, Baja California Sur, Mexico. Samples of Avicennia germinans pneumatophores from Zacatecas estuary were collected between May 2005 and May 2006. The identification of the most representative Chroococcales produced 10 morphotypes, described mor - phologically and digitally registered for the first time for Mexico. We report species of Aphanocapsa, Chroococ- cus, Hydrococcus, Chamaecalyx, Dermocarpella and Xenococcus. Some taxa have been recorded in brackish or even marine environments from other regions, evidencing the wide geographical distribution and ecological adapt- ability of these organisms, but some others are probably new to science. Some species have a specific seasonal and vertical distribution on the pneumatophore but other have a more ample distribution. Aphanocapsa littoralis and Chroococcus cf. obliteratus are new records for benthic biotopes of Pacific Mexico; Dermocarpella cf. stellata is a new record for the Gulf of California.

Abstract: A total of 77 samples from streams and rivers were found to contain populations of Tapinothrix (Pseudanabaenaceae), a genus currently confused with Homoeothrix (Oscillatoriaceae). Three species within the genus were identified: T. ozarkiana sp. nov., T. varians, and T. janthina.

Abstract: A new aerophytic species of the xanthophycean genus Excentrochloris - Excentrochloris fraunhoferiana Hofbauer, Gartner, Rennebarth, Sedlbauer, Mayer et Breuer from a building surface is described. Light microscopically investigation and sequence analyses showed a clear relationship of the new alga to Botrydiopsis constricta Broady. Cytomorphology and reproduction of the new species was investigated on cultures. E. fraunhoferiana differs from the type species E. gigas by bigger size of adult vegetative cells with obligate thickening of wall, and none amoeboid zoospores with one chloroplast. Adult zoospores are peripherically arranged in the sporangia. The relation to Botrydiopsis constricta is discussed in comparison with characters of E. fraunhoferiana.

Abstract: The CAUP (Charles University in Prague) image web-database of algae is mostly based on the heritage of the German personalities who were working at the German part of Charles University from the second half of the 19th century to the 1945 Database includes at present 275 images of herbarium specimens, 1,710 images of permanent slides and 1,044 images of living algal strains from CAUP culture collection; in total 1,135 specimens Nevertheless, many objects in the University collection remained to be non-digitalised and the original species names of objects have been only partially revised

Abstract: The cyanobacterial layer (1-3 mm) of microbial mats of Wadi Muqshin, Sultanate of Oman, in hypersaline continental pools near the Empty Quarter desert were analyzed for cyanobacterial diversity, pigments composition and antibacterial and quorum sensing inhibition activities at the microbial community level. The salinity of the ponds reached up to 75 ‰, the temperature was around 49 °C and the salt composition was similar to seawater. Cyanobacteria in pools containing coccoid and filamentous forms similar to those normally found in salt ponds and in intertidal flats were found. Among the observed taxa were Microcoleus chthonoplastes, Spirulina subsalsa, Johannesbaptistia pellucida, Chroococcidiopsis sp., Aphanocapsa sp., Chroococcus sp., Gloeocapsa sp., Schizothrix sp. and Leptolyngbya sp. Using high performance liquid chromatography (HPLC), the pigments chlorophyll a, scytonemin, chlorophyllid a, β-carotene and fucoxanthin were detected, with the highest concentrations obtained for the ultra-violet (UV) sunscreen pigment scytonemin. The chemical extracts of the microorganisms in the mats cyanobacterial layer exhibited antibacterial activity against 3 out of 9 tested pathogenic bacterial strains and showed quorum sensing inhibition activity against the reporters Agrobacterium tumefaciens NTL4 (pZLR4) and Salmonella enterica S235 but not Chromobacterium violaceum CV017. We conclude that the studied inland hypersaline microbial mats harbor similar diversity to their counterparts in intertidal flats and evaporation ponds and could produce chemical compounds that are of biotechnological significance.

Abstract: To clarify the distinctiveness of the genus Cyanospira from the related genus Anabaenopsis, a morphological study of several undescribed strains of Cyanospira and an extensive phylogenetic analysis of Anabaenopsis and Cyanospira were performed Heterocytous cyanobacterial strains were isolated from natron salt samples from the Republic of Chad containing large numbers of dormant dry akinetes Morphology, and the entire life cycle, from akinete germination to the development of mature vegetative forms, were documented Cultures of Cyanospira, obtained from the germination of desiccated akinetes, were characterized by variable filament dimensions and coiling degrees Akinete development in vegetative filaments was typically apoheterocytic; akinetes developed in chains continuously expanding along the filament; in old cultures, the whole filaments could be transformed into chains of akinetes The development pattern of akinetes in Cyanospira was definitely different from that of Anabaenopsis Phylogenetic analysis was performed using the ARB and SILVA phylogenetic tools and databases All publicly available sequences of strains belonging to the genera Anabaenopsis and Cyanospira, and sequences of our new strains, were compared with selected entries of Nostocaceae The two genera Anabaenopsis and Cyanospira formed two phylogenetically coherent and well defined sister units, mostly related to the genus Nodularia Inside the Anabaenopsis branch, a cluster exclusively composed by strains of A elenkinii and another corresponding to A nadsonii could be identified Sequences of Cyanospira formed two distinct phylogenetic clusters, respectively corresponding to the species C rippkae and C capsulata Sequences of the alkaliphilic species A abijatae were found to be members of the C rippkae subcluster As already known for halophilic cyanobacteria, also alkaliphilic cyanobacteria of the genus Cyanospira were phylogenetically separated from their mesophilic counterparts, classified under the genus Anabaenopsis We support that the differentiation of sister genera in response to selective conditions of extreme environments is a well represented evolutionary mechanism in cyanobacteria

Abstract: The Atlantic rainforest is considered one of the most important hotspots of biodiversity on Earth. This great diversity results from the variation of climatic conditions (rainy, warm and cold in high mountains), what generates a unique series of rain forest ecosystems quite distinct from each other. Unfortunately, due to the human impact over the centuries, today there are just fragments of preserved native rainforest. During the investigation about the cyanobacterial flora from the Atlantic rainforest, a special Chamaesiphon morphotype was found on a rock in streaming water. Chamaesiphon stratosus sp. nova is close to C. britannicus (Fritsch) Komarek et Anagn., C. geitleri Luther and C. fuscus (Rostaf.) Hansg ., and differs from them mainly because of the cells disposition in one layer and exocytes liberation in a sheath at the upper part of cells. These two features belong to different subgenera of Chamaesiphon (Godlewskia and Chamaesiphonopsis). Thus, the Brazilian material displays features of both subgenera and puts in evidence the fragility of these characteristics at subgenus level. Therefore, a discussion about the taxonomy of these subgenera and a proposal for including Chamaesiphonopsis as a synonym of the Godlewskia were done.

Abstract: A new species was isolated and characterized from Grand Staircase-Escalante National Monument. This taxon shares morphological characteristics with five different genera, Ammatoidea, Homoeothrix, Leptolyngbya, Phormidiochaete, and Tapinothrix. An argument could be made to place it in any of these genera, however, we consider the most taxonomically correct genus for our pseudanabaenalean species to be Tapinothrix, and we accordingly describe it as T. clintonii sp. nov. Phylogenetically, the taxon is closest to Leptolyngbya sensu stricto, but it has very distinctive morphology and 16S-23S ITS sequence and secondary structure that support our conclusion to recognize Tapinothrix as a genus separate from Leptolyngbya.

Abstract: An aerophytic Nostoc, from a Mayan monument, has been characterized by phenotypic and molecular approaches, and identified as a morphospecies of Nostoc commune. Phylogenetic analysis indicates that it belongs to a Nostoc sensu stricto clade, which contains strains identified as N. commune. Nostoc cf. commune is found in two close areas: Site I (protected from direct sunlight by a wall), where it forms biofilms on mortar with Trentepohlia aurea; and Site II, where it grows on exposed stucco with the accompanying organism Scytonema guyanense. Over the year, in a habitat dictated by alternating wet and dry seasons, the organisms vary in appearance. Its life cycle comprises two seasonally-determined developmental stages (growth during the wet season and dormancy during the dry season) and two transitional stages (preparation for the dry season, and rehydration and recovery). At the beginning of the wet season the resistant stages from the previous dry season are rehydrated and form propagula, that adopt a colonial shape surrounded by a gelatinous sheath. As conditions become drier, clearly more in Site II, N. cf. commune employs adaptative strategies agains the drought, such as reducing the number of cells inside thick ensheathed colonies. Akinetes were observed, although only in Site II and in cultures of an isolated strain. Their fine structure shows parallel arrays of whorled thylakoids and septal intercellular connections. Spectral confocal laser scanning microscopy was used to analyze the fluorescence spectra of the photosynthetic pigments. N. cf. commune shows phycocyanin, allophycocyanin and chlorophyll a in both sites. Moreover, spectra of vegetative ensheathed cells, collected at Site II at the dry season, differed in their fluorescence spectrum: they feature a peak at 564 nm, attributed to phycoerythrin, which increases cell tolerance against the detrimental effects of strong light. These findings indicate that both the distribution and persistence of N. cf. commune might stem from cumulative adaptative strategies that increase its resistance to extreme desiccation.

Abstract: The cyanobacterial genus Phormidium is polyphyletic, as follows from recent molecular and phenotypic analyses. Several isolated clusters were found also in Antarctic populations (Taton et al. 2006, Taton et al. 2010, Strunecký et al. 2010b). A few of them have already been described or revised on the generic level (e.g., Phormidesmis, Microcoleus). One of the separate clusters belongs to a group of strains identified traditionally as Phormidium murrayi, described from the Antarctica originally in 1911 as Lyngbya murrayi by W. et G.S.West. We evaluated 23 morphologically similar strains or populations resembling Ph. murrayi from the Antarctica and few other geographical regions; 6 of them were studied by us by molecular methods. Morphological characteristics and 16S rDNA similarity corresponding with typical Ph. murrayi were shared mostly by the specimens from the Antarctica. Molecular analyses confirmed that Ph. murrayi represents a special taxonomic group (on the generic level) inhabiting commonly shallow freshwater classified as a special genus in cyanobacterial taxonomy (Wilmottia gen. nov.) according to the recent "polyphasic approach". The type species of Wilmottia, W. murrayi, was determined up to now to be characteristic for the Antarctica. Other phylogenetically and morphologically similar types from other regions represent possibly different taxa (species) of the same generic unit. The specific status of similar or related strains from other regions should be therefore solved in the future.

Abstract: This paper deals with the characterization of a filamentous cyanobacterial strain, isolated from the microbial mats developing on the thermal muds of Ischia Thermal District (Naples, Italy). The survey was carried out by a polyphasic approach that includes morphological, ultrastructural, biochemical, and genetic analyses. For the molecular analyses the 16S rDNA gene and the rbcL gene were considered. All results showed that this filamentous cyanobacterium belongs to the order Oscillatoriales, family Pseudanabaenaceae. Moreover, the phylogenetic reconstruction suggests that strain ITD-01 might represent the first described entity belonging to a new cyanobacterial genus, whose name might be Protolyngbya.