Diatom Taxonomy and Ecology Research Papers (original) (raw)

Foreword to the English Edition After the time known informally by diatomists as the “Era of the Green Books” (i.e. the Süßwasserflora) which lasted about until the mid 1990s and during which all the information one needed to have to... more

Foreword to the English Edition
After the time known informally by diatomists as the “Era of the Green Books” (i.e. the Süßwasserflora) which lasted about until the mid 1990s and during which all the information one needed to have to address the central European diatom microflora was included in four books, there was an explosion of new publications as fundamental concepts underpinning the taxonomy of diatoms were revised, a large number of new species were described, and many familiar taxa bounced between genera. These are exciting times for those interested in the phylogeny,
biogeography and diversity of diatoms, but also hugely frustrating times for those concerned with the routine identification of diatoms for practical purposes. Application of the EU WFD needs a consistent approach to the naming of the organisms upon which assessments depend. HOFMANN et al. (2011) represented a welcome exception to the trend of an ever-more diffuse literature on diatoms, since it gave analysts, once again, a single identification text for the species most likely to be found during routine assessments in central Europe.
In order to facilitate use outside the German-speaking area, we decided to translate this work into English. At the same time, the lead Editor used this opportunity to update the work to include the latest information on the taxonomy and ecology. Decisions on revisions were made following a very empirical criterion: all taxonomy and ecology papers of which we are aware published until autumn 2016 were considered, and all genera and species (if quantitatively relevant)
were included if they appeared to be recognized in the main online resources (in particular, ‘Diatoms of the Unites States’, ‘AlgaeBase’ etc.), and by the community of diatomists. This is a very practical criterion, which might sometimes lead to inclusion of taxa whose merits are
still being debated, as long as it appears that they still might have some useful application in everyday practice and some recognition in applied ecology.
Following this process, 26 genera were included in the updated English edition of the book whilst in just three cases genera that were included in the first (German) edition have been removed (although they are still mentioned and briefly explained in the book). 10 species have been added to the book, 27 more have been newly mentioned under ‘Similar taxa’, taxonomic concepts were clarified / updated for 36, and 39 were transferred from one genus to another. The clarification and updating made it necessary to produce new identification keys for two
genera (Diploneis and Sellaphora). Information on plastids (only occasionally available in the German edition) has been added whenever possible to the descriptions of the genera. Terminology of both taxonomic features and also ecological concepts was updated in the Glossary. We have also improved the information on ecology and distribution for 22 species. These improvements to the text are accompanied by several additional references. Formal taxonomic
changes were carried out only when strictly necessary in order to simplify difficult situations or improve the rationale of genus affiliation: one new species description (of a morphologically distinct Sellaphora of waters of high saprobic level), seven formal transfers (comb. nov.), one
formal name changes (nom. nov.). The full text of the species descriptions of the German edition has been replaced by more schematic profiles, in which the different points are provided
in a “bullet point” style. This replaces the rich German prose, capable of conveying even nuances of the morphology, with something far more accessible to international audiences.
This English edition, like the earlier German ones, is intended primarily as a tool to facilitate consistent and accurate identification of diatoms in central Europe. We are, however, confident that it might be of general interest for all those looking for an up-to-date overview of most freshwater benthic diatom genera and of the characteristics of their most commonly encountered species.
Marco Cantonati & Martyn Kelly

Diatom algae are known to play an important role as primary producers in many diverse ecosystems including artificial aquaculture ponds were they also aid in maintaining water quality by consuming excess nutrients. But factors influencing... more

Diatom algae are known to play an important role as primary producers in many diverse ecosystems including artificial aquaculture ponds were they also aid in maintaining water quality by consuming excess nutrients. But factors influencing their growth are still poorly understood. In the present study the effect of micro nutrients, N: P ratio and silica concentration on benthic diatom Synedra sp. grown in fish pond waste water was studied along with nutrient removal efficiency. We have studied 9 different treatments of which addition of micronutrient mixture Nualgi along with adjusted N:P to 6:1 has resulted in highest cell density followed by Silicate enrichment were as only N:P adjustment and Nualgi addition has no significant effect on diatom growth. At the end of growth experiment, the N removal efficiency of treatment groups (50.23%–65.44%) were significantly higher (P < 0.05) than control group (43.56%) were as phosphate removal efficiency was significantly higher (P < 0.05) with Nualgi and N:P adjustment (53.37%–68.98%). The silicate consumption was significantly higher in control group at 63.87%, than other experimental groups. These results will give us a new insight in to important factors influencing beneficial algae growth and simultaneous nutrient removal from aquaculture waste water.

The Upper Paraná River floodplain is one of the few remaining non-dammed stretches in Brazil. It has a typical fluvial dynamics represented by the flood pulse and a highly complex habitat, which allows the existence and maintenance of a... more

The Upper Paraná River floodplain is one of the few remaining non-dammed stretches in Brazil. It has a typical fluvial dynamics represented by the flood pulse and a highly complex habitat, which allows the existence and maintenance of a great biodiversity, including diatom species. As it happens in tropical lowland environments, also in this floodplain, the genus Eunotia is one of the most diverse and abundant diatom groups. Therefore, this study addresses morphologic and morphometric details of a new species and the most abundant Eunotia species in sediment cores from two wetland lakes. The morphological characteristics from each species were obtained through microscopy documentation of cell walls, and compared with other related species.

High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens.... more

High-resolution images of phytoplankton cells such as diatoms or desmids, which are useful for monitoring water quality, can now be provided by digital microscopes, facilitating the automated analysis and identification of specimens. Conventional approaches are based on optical microscopy; however, manual image analysis is impractical due to the huge diversity of this group of microalgae and its great morphological plasticity. As such, there is a need for automated recognition techniques for diagnostic tools (e.g. environmental monitoring networks, early warning systems) to improve the management of water resources and decision-making processes. Describing the entire workflow of a bioindicator system, from capture, analysis and identification to the determination of quality indices, this book provides insights into the current state-of-the-art in automatic identification systems in microscopy.

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new... more

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new Navicula species from springs with these characteristics within the basin of the River Adige in the south–eastern Alps and Alpine foothills (Province of Verona, Italy). Navicula veronensis sp. nov. is in the group of species around N. cincta but has distinct outline, size, central area, and proximal raphe endings. The availability of data on the distribution of the new species in streams of the Island of Cyprus allowed to quantitatively compare the ecological preferences, niche position, and niche breadth of Navicula veronensis sp. nov. with those of allied species. The new species was found to be characteristic of medium–high conductivity freshwaters, rich in sulphates and chloride, often nitrate enriched and affected by marked discharge fluctuations and seasonal desiccation. Niche position however differed only slightly from those of morphologically–similar species, with the exception of Navicula dealpina that was found to be characteristic of oligotrophic, calcium– bicarbonate rich environments with medium(–low) conductivity. Canonical Correspondence Analysis clearly showed that the most influential environmental variables determining the diatom assemblages of low–elevation carbonate springs affected by anthropogenic disturbance were nitrate enrichment, spring morphology alteration (in particular for water abstraction), and low discharge.

Correct identification of diatom taxa is indispensable for diatom-based water quality studies, as well as for biotechnological applications. Biological applications of taxonomy include the identification of taxa from particular specimens.... more

Correct identification of diatom taxa is indispensable for diatom-based water quality studies, as well as for biotechnological applications. Biological applications of taxonomy include the identification of taxa from particular specimens. In this regard, identification keys, that use a predetermined set of characters to identify a given individual, are not commonly employed by diatom specialists due to the extreme biological diversity found in this group of microalgae. This chapter reviews previous attempts of using taxonomic keys for diatom identification, highlighting the pros and cons of the use of this and similar methods. The main morphological features found in common freshwater diatom genera are briefly presented, together with an account of the historical development of technologies used for species description.

Diatoms are extremely diverse ubiquitous microalgae. This makes them good indicators of the quality of aquatic ecosystems, and they have been used for this purpose for the past 50 years. Since 2000, the European Water Framework Directive... more

Diatoms are extremely diverse ubiquitous microalgae. This makes them good indicators of the quality of aquatic ecosystems, and they have been used for this purpose for the past 50 years. Since 2000, the European Water Framework Directive has required them to be used for assessing the ecological quality of watercourses.
A typological framework has to be devised in order to compare rivers that are comparable, i.e. rivers with the same bioclimatic regions, that flow over the same geological substrate at similar altitudes. Various ecoregional classifications have been defined using these parameters. At a scale covering 4 European countries (Spain, France, Italy, and Switzerland) and at a regional scale (north-east France) we show that ecoregions and geology are determinant in explaining communities, and that pollution-related parameters are less important. Unlike some other authors, we did not observe any homogenization of communities as the level of pollution level increased. Moreover, we did not observe geographically restricted communities, which make it possible to pool data from geographically distinct ecoregions with the same physical characteristics.
Diatoms display a very high degree of species diversity, which can be a problem for their routine use as assessment tools. We showed that when the precision of identification was increased from sub-division to species level, pollution assessment performances also increased, but to a much less marked extent than the number of taxa. Assessment performances at the genus and species levels are similar, whereas there are ten time more species than genera. We also showed that simplifying metrics (life-forms, ecological guilds) can be used to assess nutrient levels as effectively as diatom indices based on species. Furthermore, these metrics provide additional information about biofilm structure that is not available from species-based data.
Finally, micropollutant pollution of rivers is of increasing concern to citizens. We hypothesize that diatoms could be good candidates for assessing herbicide pressure. Four experiments lasting 2 months were conducted in lotic mesocosms. We showed that diatoms surrounded by thick exopolysaccharide matrices were more resistant to dissolved pesticides. On the other hand, diatoms with a high cell surface in contact with the water were disadvantaged. This kind of metric could be used in situ at a larger scale.
We conclude that these metrics could be useful for the purposes of diatom bioassessment. However, we also stress the importance of combining phylogeny and ecology to clarify which environmental pressures are forcing diatoms to adapt. Such studies will enhance diatom bioassessment.

Last year (2007) in Berlin the 21. Deutschsprachiger Diatomologen Treffen became at the same time the 1st Central European Diatom Meeting. This change was underlined by an evident increase in the number of participants. This trend... more

Last year (2007) in Berlin the 21. Deutschsprachiger Diatomologen Treffen became at the same time the 1st Central European Diatom Meeting. This change was underlined by an evident increase
in the number of participants. This trend continued with the second edition of the congress: The 2nd Central European Diatom Meeting in Trento. This was somewhat unexpected since this year (2008)
also the International Diatom Symposium will take place in a few months (07-13/09/2008) in Dubrovnik, Croatia, and several delegates announced that they would not be able to attend both meetings. In spite of this, as can be seen in Fig. 1, about hundred delegates registered for the Congress. It is therefore with satisfaction that we have the possibility to observe that their nationalities are very diverse, with an important contribution from non-German speaking countries
(Italy – “location effect” -, Czech Republic, Russia). We feel very honoured in acknowledging that some participants made long journeys to join our Congress, coming e.g. from Scotland, the eastern part of Russia, Israel, and Canada! Not surprisingly most of the participants work in Universities, but a significant share carries out its diatom investigations in other research institutions (e.g. Research Councils), and in Museums and Botanical Gardens (Fig. 2). This last observation is of special interest for us, since this year the Congress is organized in a Museum. In such Institutions, fundamental research (in particular
biodiversity documentation), collections, and educational issues and popularization are topics of prominent importance.
The topics covered by the contributions of the participants are diverse, but could be grouped into the categories shown in Fig. 3. These give an idea of ongoing diatom research in Central Europe. Not surprisingly biodiversity remains an important topic. Less obvious and – in our opinion encouraging – is the attention still given to taxonomy, a discipline which has difficulties in being acknowledged as a fundamental tool of ecological and applied research by administrators and decision makers.
In thanking the participants for coming to Trento and contributing to the Congress, we are happy that the Trentino Nature & Science Museum of Trento, a town that is not German speaking but that has always been a gate for those coming from Italy and approaching the German-speaking
area, can contribute to the continuation of the Central European Diatom Meetings, formerly Deutschsprachige Diatomologen Treffen.

Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre... more

Para facilitar y homogeneizar el tratamiento y la interpretación de la información generada en las redes de control biológico se presenta una colección de fichas descriptivas de los organismos fitobentónicos que incluyen: nombre científico, común, sinónimo, propiedades, descripción, ecología, ruta taxonómica e índices y métricas, foto o ilustración incluyendo la propiedad y el autor. Esta guía ha sido elaborada por la Dirección General del Agua y forma parte de una colección de cinco tomos.

The Island of Majorca (Spain) is characterized by a Mediterranean climate and a karstic geology that favors the formation of numerous springs and spring–fed streams on the island’s Northwester zone. Water and epilithic diatom samples... more

The Island of Majorca (Spain) is characterized by a Mediterranean climate and a karstic geology that favors
the formation of numerous springs and spring–fed streams on the island’s Northwester zone. Water and epilithic diatom
samples were collected from two springs and four spring–fed streams, located at altitudes ranging from 0 to 756 m a.s.l.,
in different seasons between 2005 and 2008. Water chemistry in these systems is characterized by high concentrations of
dissolved calcium and pH values ranging from 6.6 to 8.4. A total of 111 diatom taxa belonging to 40 genera were found and
the most abundant taxa were illustrated with LM and SEM. The diatom communities of the studied sites were dominated by
species such as Achnanthidium minutissimum, A. pyrenaicum, Amphora pediculus, Cymbella vulgata, Diploneis separanda,
Encyonopsis minuta, Gomphonema lateripunctatum and Navicula cryptotenella, reflecting the calcareous geological nature
of Majorca Island. In the framework of the study 22 diatom taxa, which are new for Balearic Islands were recorded, such
as Achnanthidium straubianum, Amphora indistincta, Cymbella lange–bertalotii,Encyonopsis subminuta, Karayevia kolbei,
Navicula aff.margalithii, N. reichardtiana and N. subalpina. In addition, a new freshwater diatom species belonging to the
genus Cymbopleura,C. margalefii was found in the Torrente of Deià. Cymbopleura margalefiiis described as a new species
based on LM and SEM observations, and compared with similar taxa. A checklist of the 309 diatom taxa recorded so far from
the Balearic Islands is also presented.

The diatom Didymosphenia geminata (Lyngbye) M.Schmidt has been commonly considered a taxon restricted to pristine habitats in mountainous areas of circumboreal regions. Recent studies show that it has a broader distribution and ecological... more

The diatom Didymosphenia geminata (Lyngbye) M.Schmidt has been commonly considered a taxon restricted to pristine habitats in mountainous areas of circumboreal regions. Recent studies show that it has a broader distribution and ecological amplitude. This shift seems to have occurred recently, as it now forms large growths in rivers within its native geographical area (North America, Europe) but also mass developments have recently appeared in New Zealand, where it is considered an aggressive invasive species with dramatic ecological and economic impacts. This nuisance organism grows attached in streambeds and may impact freshwater fish and aquatic plants and insects, causing severe disturbance in food webs. This paper investigates the historic and current biogeographic range of this invasive species (and varieties) based on 1000 citations collected mainly from the scientific literature. The locations where this diatom has appeared, including both fossil and recent records, are presented in world distribution maps. Our results confirm that the native range of D. geminata is almost restricted to the Holarctic region, though its distribution area is broader than usually reported in the literature. The ecological profile of this alga, along with its nuisance effects, is also discussed. Excessive growths do not only appear in areas where this species is presumably exotic. Contrarily to general statement, reports of mass developments of D. geminata date back to the 19th century. World references to D. geminata have increased exponentially during the last decades; however; with respect to the whole diatom literature during the XIX and XX centuries, the relative frequency of citations has decreased progressively.

El presente trabajo supone una contribución al conocimiento de las diatomeas dulceacuícolas españolas. Se describe la diatomea Eunotia emmae sp. nov. a partir de muestras de algas epífitas recogidas en una laguna somera oligo-mesotrófica... more

El presente trabajo supone una contribución al conocimiento de las diatomeas dulceacuícolas españolas. Se describe la diatomea Eunotia emmae sp. nov. a partir de muestras de algas epífitas recogidas en una laguna somera oligo-mesotrófica de la provincia de León. La muestra fue tomada y procesada siguiendo los protocolos comunes para diatomeas lacustres. Las características morfológicas y ultraestructurales de este nuevo taxón se detallan e ilustran mediante imágenes de microscopía óptica y electrónica. La diagnosis diferencial con otras especies afines muestra que la combinación de caracteres de E. emmae (principalmente la forma biconvexa de la valva y un conspicuo sternum) es única. Abstract This work aims at contributing to the knowledge of Spanish freshwater diatoms. The diatom Eunotia emmae sp. nov. is described from samples of epiphytic algae collected in a shallow, oligo-mesotrophic lake from the province of Leon (Spain). The sample was taken and processed following the usual protocols for lacustrine diatoms. Morphological and ultrastructural features of this new taxon are detailed and illustrated by means of light and scanning electron microscopy images. Differential diagnosis against related species shows that the combination of features in E. emmae (mainly the presence of biconvex valves and a conspicuous sternum) is unique.

A factorial experiment was carried out in order to assess the effects of four treatment steps in diatom processing techniques (the quantity of hydrogen peroxide added to the sample, the time allowed to the digestion reaction, the use of... more

A factorial experiment was carried out in order to assess the effects of four treatment steps in diatom processing techniques (the quantity of hydrogen peroxide added to the sample, the time allowed to the digestion reaction, the use of centrifugation and the method used to settle the frustules onto the coverslip) on different aspects of the quality of the resulting microscopic slide: the concentration of organic and inorganic matter, the density, randomness and homogeneity of the frustule distribution in the slide, and the abundance of broken frustules and girdle views. The results show no significant effects of any of the experimental treatments on the proportion of broken frustules in the samples. No significant effects were related to the duration of the oxidation reaction in any of the aspects evaluated in the quality of the slides. A sample:hydrogen peroxide ratio of 1:1 for a 6-h oxidizing reaction can be used to optimize the protocol. Despite being more time consuming, the use of successive decantations instead of centrifuging is more appropriate to achieve better results. Slide quality can also be improved by leaving the coverslips to dry at room temperature in order to improve the distribution of frustules.

Marine epiphytic diatoms in the Antarctic Peninsula have not been studied in detail previously, and information on their distribution and occurrence is scarce. We studied the marine epiphytic diatoms on several species of macroalgae... more

Marine epiphytic diatoms in the Antarctic Peninsula have not been studied in detail previously, and information on their distribution and occurrence is scarce. We studied the marine epiphytic diatoms on several species of macroalgae belonging to the Rhodophyta, Phaeophy-ceae and Chlorophyta. We recorded a total of 50 epi-phytic diatoms, with Cocconeis spp., Entopyla australis var. gigantea, Grammatophora arctica, Licmophora antarctica and Pseudogomphonema kamtschaticum the most common taxa. Diatoms appeared to have substra-tum preferences rather than site preferences. The most frequent hosts for diatom attachment were the rhodo-phytes Pantoneura plocamioides, Delesseria lancifolia and Georgiella confluens. Phaeophytes were less favourable hosts, and no diatoms were recorded on the chlorophytes.

Diatoms are a widespread group of organisms with well-known ecological preferences. Knowledge of their diversity is of great importance for assessing the environmental status of different aquatic ecosystems. The present study was based on... more

Diatoms are a widespread group of organisms with well-known ecological preferences. Knowledge of their diversity is of great importance for assessing the environmental status of different aquatic ecosystems. The present study was based on 55 different localities that included rivers, streams, channels, accumulations and salt marshes throughout Serbia. The results of this study expanded the diatom checklist by 80 taxa, including two new recorded genera (Fistulifera and Microfissurata) for Serbia. The data were obtained by combining light microscopy (LM) and scanning electron microscopy (SEM) that provided reliable identification, which is very important in diatom diversity studies.

The Water Framework Directive (WFD) requires that the European Union countries determine the biological state of their waters with respect to sites of high quality. Despite bioindicators have been widely applied in running waters and deep... more

The Water Framework Directive (WFD) requires that the European Union countries determine the biological state of their waters with respect to sites of high quality. Despite bioindicators have been widely applied in running waters and deep lakes throughout all Europe, little is known about their applicability in shallow lakes. In this context, the objective of this work is to check the effectiveness of epiphytic diatoms as indicators of the trophic state in six shallow lakes of León Province (NW Spain). Epiphyton was sampled from helophyte stems in six shallow lakes covering different ecological conditions. A significant correlation was found between the total nitrogen concentration and the diatom indices SPI (Specific Polluosensitivity Index) and BDI (Biological Diatom Index), this correlation being lower with respect to the total phosphorus concentration. The classification of the lakes according to the trophic and saprobic levels based on diatoms corresponds to that obtained from the analysis of the limnological and chemical parameters of the studied systems. Despite the use of these indices has been traditionally limited to rivers and channels, our results show the effectiveness of epiphytic diatoms as biological indicators of the quality of water in Mediterranean shallow lakes and the applicability of common diatom indices for biomonitoring purposes in these aquatic ecosystems.

A cross-check of botanical names databases revealed the presence of 19 cases of homonymy which are hereby resolved by proposing replacement names. Most cases concern diatom genera (Bacillariophyta) names which are preoccupied by... more

A cross-check of botanical names databases revealed the presence of 19 cases of homonymy which are hereby resolved by proposing replacement names. Most cases concern diatom genera (Bacillariophyta) names which are preoccupied by spermatophytes. While Loranthella nom. nov. (Spermatophyta, Loranthaceae) and Ochradiscus nom. nov. (Spermatophyta, Resedaceae) are proposed as new names for spermatophytes, new diatom names are proposed for genera that are currently placed in the families Amphipleuraceae, Coscinodiscaceae, Hemiaulaceae, Hemidiscaceae, Melosiraceae, Metascolionei-daceae nom. nov., Naviculaceae, Pyxillaceae, Stictodiscaceae and Surirellaceae. With one exception (i.e. Eileencoxia nom. nov.) all remaining diatom genera that are discussed in the present paper are marine and/or fossil elements. The particulari-ties of each case are briefly discussed. A total of one hundred and three new combinations are proposed.

e present work provides a first insight into the structure of epiphytic diatom assemblages inhabiting some dominant vegetation of the Huwaiza marsh, which is one of the most ecologically important wetlands in the Middle East. A total of... more

e present work provides a first insight into the structure of epiphytic diatom assemblages inhabiting some dominant vegetation of the Huwaiza marsh, which is one of the most ecologically important wetlands in the Middle East. A total of 74 taxa belonging to 38 genera were recorded, of which Cocconeis pla-centula var. euglypta and Fragilaria pulchella predominate. Epiphytic diatom assemblages in Huwaiza marsh are a mixture of truly freshwater taxa (oligohalobous, 39%), brackish water taxa (mesohalobous, 33%) and marine forms (polyhalobous, 12%). Marine taxa have probably been transported into the marsh from the sea.

Doñana temporary ponds (southwest Spain) form a system of water bodies of remarkable ecological singularity with a high protection status. However, its species composition, diversity, and distribution of algal communities are largely... more

Doñana temporary ponds (southwest Spain) form a system of water bodies of remarkable ecological singularity with a high protection status. However, its species composition, diversity, and distribution of algal communities are largely unknown. During a biological survey carried out in shallow temporary ponds in 2010, several unknown diatom taxa were found in various population densities in the epiphyton of these systems. Detailed light and scanning electron microscopy observations allowed the description of five of them (Eunotia vozmedianoi, Planothidium lacustre, Halamphora tharsis, G. undulans and Pinnularia acidophila var. baetica) as taxa new to science. Differential diagnostic criteria with respect to similar taxa, together with ecological and biogeographical implications of these findings, are briefly discussed. Our results support recent studies indicating that endemism in diatoms might be a widespread pattern.

In 2000 the European Parliament and The European Union Council recommended that member countries assess water quality using diatoms, as part of the phytobenthos. In Italy this recommendation has given new impetus to the study of diatom... more

In 2000 the European Parliament and The European Union Council recommended that member countries assess water quality using diatoms, as part of the phytobenthos. In Italy this recommendation has given new impetus to the study of diatom communities and the application of biotic indices. During the summer of 2004, a total of 11 rivers of the Trentino province (Northern Italy) were sampled, revealing the presence in low abundances of the diatom Didymosphenia geminata (Lyngbye) M. Schmidt. The sites where this diatom occurred were characterised by a low pollution impact; they were also lake fed or had a regulated flow regime, although with different geologies. Morphological features of D. geminata frustules were analysed using LM and SEM and specimens could be referred to the morphotype "geminata". In many countries this species is expanding its distribution and in New Zealand it is considered an invasive alga. This work provides an initial report on the presence of D. geminata in the Trento province, and contributes to increasing the knowledge on its distribution in Italy and its ecology in the Alps.

The late Miocene (Tortonian) diatoms in 21 outcrop samples from Neil Island, Andaman and Nicobar Islands were investigated with eighty two planktonic and benthic taxa belonging to 35 genera. Principal Component Analysis reveals the... more

The late Miocene (Tortonian) diatoms in 21 outcrop samples from Neil Island, Andaman and Nicobar Islands were investigated with eighty two planktonic and benthic taxa belonging to 35 genera. Principal Component Analysis reveals the existence of two distinct groups; samples dominated by Thalassionema nitzschioides and Thalassiothrix longissima, belong to one group and the other group is dominated by Actinocyclus ellipticus, Azpeitia nodulifera, Coscinodiscus asteromphalus and C. radiatus. Five palaeoecological zones have been proposed with the help of CONISS cluster analysis according to the dominance of diatom taxa. To ascertain high resolution palaeoecological zones SHEBI analysis was carried out, which reveals seven zones. The studied outcrop is also characterised by the late Miocene marker radiolarians of RN8 and RN9 zones. The overall analysis indicates a strong monsoonal system; however there are evidences of relatively weaker intermittent monsoonal activity. The diatom planktonic/benthic ratio shows evidence of minor sea level fluctuations during that period. The dominance of the upwelling diatom taxon Thalassionema nitzschioides confirms the strong monsoonal activity during the late Miocene in the study area.

The diatom microflora collected from glacial lakes, peat-bogs, springs, streams, rivers and wetlands on 352 localities on Shara Mountain and 124 localities on Nidze Mountain, Macedonia, was investigated between 1995 and 2003. A total of... more

The diatom microflora collected from glacial lakes, peat-bogs, springs, streams, rivers and wetlands on 352 localities on Shara Mountain and 124 localities on Nidze Mountain, Macedonia, was investigated between 1995 and 2003. A total of 418 taxa from 76 genera, were identified. The taxa are predominantly oligotrophic or dystrophic. Total floristic similarity between the neighbouring mountain sytems (100 km apart) was only 22.74%. One of the sites has been influenced by glaciation, while the other contained habitats that served as glacial refugia. Taxa from the refugia are highly similar to the those of the ancient Ohrid and Prespa lakes in Macedonia. The morphological features and taxomic position of 11 taxa are discussed.

"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main... more

"The Duero River Basin, with an area of 97290 km2 and more than 40000 km of streams, is the largest one in the Iberian Peninsula, and lies mainly under Mediterranean continentalized bioclimate. Aquatic ecosystems are endorheic and main watercourses are regulated and highly anthropized. As in every lotic environment, benthic algae play a key role in the structure and functioning of its ecosystems and, within this group, diatoms represent the most abundant and diversified component. Their biological features make them excellent water quality indicators, and this has promoted their study at international level. As a result of the implementation of the Water Framework Directive of the European Union, ecological status biomonitoring networks have been established in all Iberian basins, based on the use, among others, of diatom indices, which has led to the need of more detailed taxonomic and ecological studies on these organisms. Despite their relevancy, such works are still scarce in Spain. In the Duero Basin, up to date more than 500 diatom species have been recorded, a high floristic richness that contrasts with analogue regions, this being related to the large diversity of environmental conditions included within this zone.
The aim of the present work is to elaborate a practical identification guide in accordance with the needs of technicians and biologists evaluating water biological quality in the Duero Basin. This book gathers the 200 main diatom taxa in terms of abundance and occurrence, selected from more than 600 samples of river epilithon collected during annual surveys carried out between 2003 and 2007 in the Spanish part of the basin. Certain taxa that could not be identified to specific level are also presented. For every diatom species, the following information is provided: a mor-phometric and autoecological description, a selection of illustrated bibliographic references and an iconographic series illustrating the taxon’s morphological variability, with a total of 3110 photographs in light and scanning electron microscopy gathered into 109 plates. The nomenclature, taxonomy and systematic position of taxa follow the most recent phycological literature. 116 species new to the Duero Basin and 34 species new to the Iberian Peninsula are presented."

Populations of a fragilarioid diatom from inter-dune lakes of the badain Jaran Desert (northern China), originally identified and reported under the name Fragilaria sp. cf. famelica, were investigated in detail using light and scanning... more

Populations of a fragilarioid diatom from inter-dune lakes of the badain Jaran Desert (northern China), originally identified and reported under the name Fragilaria sp. cf. famelica, were investigated in detail using light and scanning electron microscopy. the analyses indicate that most of the morphological features of this taxon are identical to Williamsella angusta graeFF, koCIolek & S.r. ruShForth, the type species of the genus Williamsella recently described from blue lake warm spring (utah, uSa). the criteria used to separate Williamsella from Fragilaria (i.e. the presence/absence of spines, the colonial formation, the preference for saline vs freshwater habitat, and the coverings of the areolae) are not supported and
the genus is refuted. Instead the new combination Fragilaria crenophila comb. nov. is proposed for the blue lake species.
the taxon from the badain Jaran desert lakes represents a varietal population that is characterized by shorter valve length and lower stria density than the nominal variety, and is given the name Fragilaria crenophila var. sinensis. a discussion of the taxonomy, ecology and geographical distribution of this taxon is presented and a detailed comparison with Fragilaria asiatica hustedt, a very similar species described from northern tibet (China) is made.

The present study refers to the effect of metal pollution on diatoms by describing a new form of teratology. The samples were collected in the Abrud River, located in a mining area from Romania, where an unreported type of deformity is... more

The present study refers to the effect of metal pollution on diatoms by describing a new form of teratology. The samples were collected in the Abrud River, located in a mining area from Romania, where an unreported type of deformity is observed in the diatoms Achnanthidium sp. pl. This kind of teratology has been found in the 20.5\% of individuals of the population and affects the cingulum, in particular to the valvocopula, by becoming markedly undulate.

Cocconeis costutu var. subunturcticu var. nov., a rare taxon from the Kerguelen Archipelago (Southern Ocean, Indian sector), is described using light and scanning electron microscope observations and was compared to related taxa. Apart... more

Cocconeis costutu var. subunturcticu var. nov., a rare taxon from the Kerguelen Archipelago (Southern Ocean, Indian sector), is described using light and scanning electron microscope observations and was compared to related taxa. Apart from the wide-elliptical central area
devoid of striae, the raphe valve features highly resemble those of the C. costutu complex: the open cristu marginalis is similar to the one occurring in other varieties of C. costutu,
whereas the slightly dissymmetric and hook-like central raphe endings are a distinctive
feature. This Subantarctic diatom has a two-layered sternum valve, with alveolate striae
consisting of elongated chambers internally open through marginal elliptical wide and
regular foramina. On the external side, striae of the sternum valve vary from biseriate to
triseriate near the margin, and are not restricted to the foramina location. The resemblance of
our new taxon with C. costutu var. puci$cu and C. burleyi, which also possess more or less
extended SV chambers, is discussed. The epizoic diatom genera Bennettella and Epipellis,
previously assigned to the genus Cocconeis Ehrenberg, also show such alveolate-chambered
striae, but are associated with several other very specific features. Several small sized
Cocconeis taxa from Antarctic and Subantarctic environments, such as C. costutu var.
anturcticu and C. melchiori, show a certain morphological similarity to Cocconeis costutu
var. subunturcticu var. nov., but they have marginal short striae on the sternum valve and
lack a two-layered sternum valve or chambers.

Two new species of Mastogloia, M. abnormis and M. descrepata, are described from the saline Sawa Lake, in South Iraq. These species belong to the Mastogloia section Sulcatae, which is characterized by the presence of a central furrow on... more

Two new species of Mastogloia, M. abnormis and M. descrepata, are described from the saline Sawa Lake, in South Iraq. These species
belong to the Mastogloia section Sulcatae, which is characterized by the presence of a central furrow on the external valve face. Descriptions
of these species are based on light microscope (LM) and scanning electron microscope (SEM) features that distinguish them from
other taxa. Mastogloia abnormis exhibits few morphological features that are not shared by any described species in the genus, while
M. descrepata is similar to, but distinct from, M. vestigiostriata, M. belaensis, and M. braunii. Both taxa were found as epiphytes on
the submerged Lamprothamnium sp. that is dominant on the bottom of Sawa Lake. Environmental conditions where the species were
common included high salinity and elevated concentrations of calcium sulphate (gypsum). The ecology of these new species is discussed.

A population of an unknown Psammothidium species (Bacillariophyta, Achnanthidiaceae) was found in core sediments collected from Cimera Lake, an oligotrophic, undisturbed mountain lake in Central Spain (Gredos mountain range). The... more

A population of an unknown Psammothidium species (Bacillariophyta, Achnanthidiaceae) was found in core sediments collected from Cimera Lake, an oligotrophic, undisturbed mountain lake in Central Spain (Gredos mountain range). The morphology and ultrastructure of this taxon is hereby documented in detail by means of light (LM) and scanning electron (SEM) micrographs. Morphologically, the closest taxon is P. levanderi, and the type of this species is analyzed here to provide a differential diagnosis. A comparison with other similar small Psammothidium species with an elliptic outline show that the combination of features exhibited by this taxon is unique and it is thus described here as Psammothidium toroi sp. nov.

This study presents investigations of the periphytic diatoms on artificial (glass slides) and natural substrates in the karstic, limnocrene spring of Bunica situated in the south of Bosnia and Herzegovina. Investigations were performed in... more

This study presents investigations of the periphytic diatoms on artificial (glass slides) and natural substrates in the karstic, limnocrene spring of Bunica situated in the south of Bosnia and Herzegovina. Investigations were performed in summer 2010. Samples were collected every seven days for eight weeks. Physical and chemical characteristics of water, temperature, oxygen saturation, dissolved oxygen, electric conductivity and nutrients as well as flow velocity at sample site, were measured simultaneously with each sampling. Physical and chemical characteristics showed low temperature oscillations, good aeration and oligotrophic conditions. In general, greater diatom diversity was noted on natural substrate. A total of 104 diatom species were found on natural substrate and 82 on glass slides. The best represented genera on both types of substrate were Gomphonema and Navicula (each with eight species), Nitzschia (with six species), and Cocconeis (with five species). Achnanthidium exiguum, Achnanthidium minutissimum, Amphora pediculus, Cymbopleura amphicephala and Surirella minuta were recorded in all samples of natural substrate and Gomphonema minutum in artificial substrate samples.

During an investigation on the diatom communities of volcanic lakes of Northeastern China a new species belonging to the “Cyclotella comta species complex” was observed. This taxon forms relatively large populations in the phytoplankton... more

During an investigation on the diatom communities of volcanic lakes of
Northeastern China a new species belonging to the “Cyclotella comta species complex” was
observed. This taxon forms relatively large populations in the phytoplankton of Lake
Tuofengling Tianchi, a 33m-deep, oligotrophic, crater lake located in Inner Mongolia. In this
paper, the valve morphology and ultrastructure of this taxon is described using light and
scanning electron microscopy and a new name, Lindavia khinganensis sp. nov., is proposed.
A discriminant analysis based on morphological LM and SEM data confirmed that
L. khinganensis is distinct from other Lindavia species with a similar morphology such as
L. comta (Ehrenberg) Nakov et al., L. radiosa (Grunow) De Toni & Forti, L. balatonis
(Pantocsek) Nakov et al., L. praetermissa (Lund) Nakov et al. and L. tenuistriata (Hustedt)
Nakov et al. In addition, the seasonal and interannual distribution of L. khinganensis was
investigated using sediment trap samples collected over a two-year period. Limnological data
from Lake Tuofengling, including water chemistry and temperature recording from a
thermistor chain provided complementary information about the ecology of this new species.
This species was not found in any other lakes from Northeastern China that we investigated.

A new benthic freshwater diatom, Fragilaria rinoi Almeida & C.Delgado sp. nov., is described from river periphyton samples in Portugal. Fragilaria rinoi sp. nov. is illustrated and discussed based on populations collected from the Vouga,... more

A new benthic freshwater diatom, Fragilaria rinoi Almeida & C.Delgado sp. nov., is described from river periphyton samples in Portugal. Fragilaria rinoi sp. nov. is illustrated and discussed based on populations collected from the Vouga, Mondego and Lis river basins in central Portugal and compared with the type material of Fragilaria vaucheriae (Kütz.) J.B.Petersen. The morphological features of the new diatom species are documented through light and scanning electron micrographs, including a comparative analysis with related species of the genus (F. candidagilae Almeida, C.Delgado, Novais & S.Blanco, F. intermedia Grunow in Van Heurck, F. neointermedia Tuji & D.M.Williams, F. recapitellata Lange-Bert. & Metzeltin, F. perminuta (Grunow) Lange-Bert., F. vaucheriae and F. microvaucheriae C.E.Wetzel & Ector). Fragilaria rinoi sp. nov. is characterized by solitary cells without spines, lanceolate valves with slightly rostrate apices, a narrow, linear axial area, and a large, unilateral central area. Fragilaria rinoi sp. nov. may be confused with F. microvaucheriae in terms of length, striae density and outline, although a morphometric analysis revealed that F. rinoi sp. nov. is significantly wider. Fragilaria rinoi sp. nov. is present in rivers with high dissolved oxygen concentrations, medium to high conductivity, neutral to slightly alkaline pH and high mean values of nitrates and ammonium.

A marine species of Cocconeis (Bacillariophyta) from coral reef lagoon of Tahiti Island (Society Archipelago, South Pacific) was identified as Cocconeis pinnata W. Gregory ex Greville. Neither drawings nor micrographs of the raphe valve... more

A marine species of Cocconeis (Bacillariophyta) from coral reef lagoon of Tahiti Island (Society Archipelago, South Pacific) was identified as Cocconeis pinnata W. Gregory ex Greville. Neither drawings nor micrographs of the raphe valve (RV) of C. pinnata are available in the literature. The examination of Gregory's type material (several slides annotated 'Arran 57' from Greville's collection housed in BM, British Museum, London, U.K.) allowed us to complete and emend the C. pinnata description. Lectotypification of C. pinnata is proposed. Since the raw material used by Gregory was not found, no scanning electron microscope (SEM) observation of type material can be provided. Except for Hustedt (1933) and a few later reports, all descriptions and illustrations agree with the original description. LM and SEM observations demonstrate that the sternum valve (SV) stria arrangement of specimens from Tahiti match those of the type. The description of the RV by Grunow in Van Heurck (1880) refers to a stria pattern very similar to that of C. pseudomarginata W. Gregory. The RV of C. pinnata, as revealed in LM and SEM, has a dense striation and no internal marginal rim. Both valves of C. pinnata have areolae with remarkable arborescent volae, which is a new feature for Cocconeis. Cocconeis pinnata is cosmopolitan, from cold-temperate to tropical areas. Several taxa have been formerly assigned to C. pinnata, though they are probably varieties of C. costata.

The terrestrial diatom Microcostatus schoemanii sp. nov. is described from dry soils of the Faan Meintjies Nature Reserve (North-West Province, South Africa). Microcostatus cholnokyi sp. nov. and Microcostatus angloensis sp. nov. are... more

The terrestrial diatom Microcostatus schoemanii sp. nov. is described from dry soils of the Faan Meintjies Nature Reserve (North-West Province, South Africa). Microcostatus cholnokyi sp. nov. and Microcostatus angloensis sp. nov. are described from sandy soils at a colliery near the town of Kriel (Mpumalanga Province, South Africa). The morphology of these taxa is examined using both light (LM) and scanning electron microscopy (SEM) and new taxa are compared with similar species. In M. schoemanii the density of the striae combined with the valve outline and the distance between the central raphe endings are the main distinguishing morphological features. M. cholnokyi is differentiated by the presence of a conopeum and the distinct structure of the microcostae. M. angloensis is similar to M. schoemanii but differentiated by the shape of the cell and the apices, the angle of striation and the distance in between the proximal raphe endings.

Biotic indices based on macro-invertebrates and diatoms are frequently used to diagnose ecological quality in watercourses, but few published works have assessed their effectiveness as biomonitors of the concentration of micropollutants.... more

Biotic indices based on macro-invertebrates and diatoms are frequently used to diagnose ecological quality in watercourses, but few published works have assessed their effectiveness as biomonitors of the concentration of micropollutants. A biological survey performed at 188 sites in the basin of the River Duero in north-western Spain. Nineteen diatom and six macro-invertebrate indices were calculated and compared with the concentrations of 37 different toxicants by means of a correlation analysis. Several chemical variables analysed correlated significantly with at least one biotic index. Sladecˇek’s diatom index and the number of macro-invertebrate families exhibited particularly high correlation coefficients. Methods based on macro-invertebrates performed better in detecting biocides, while diatom indices showed stronger correlations with potentially toxic elements such as heavy metals. All biotic indices, and particularly diatom indices, were especially sensitive to the concentration of fats and oils and trichloroethene.

Several methods for water quality assessment have been proposed for European rivers. The EU Water Framework Directive requires the use of ecological indicators for stream monitoring networks and has encouraged research on biological... more

Several methods for water quality assessment have been proposed for European rivers. The EU Water Framework Directive requires the use of ecological indicators for stream monitoring networks and has encouraged research on biological indices. However, there is a lack of integrative studies comparing the efficiency of such methods in the determination of the ecological status in rivers. The present work, carried out in the Spanish side of the Duero Basin, the largest in the Iberian Peninsula, aimed at comparing different water quality indices. The survey was conducted during autumn 2003 and summer 2004 in 95 sites covering the entire basin. Epilithic diatoms and benthic macroinvertebrates were sampled and analysed following standard methods for the calculation of the macroinvertebrate index IBMWP and 18 different diatom indices. Additionally, water physical and chemical variables were measured and Habitat (IHF) and Riparian (RQI) indices were determined in situ. In general, both diatom and macroinvertebrate indices were strongly correlated with each other and with abiotic factors. The highest correlation coefficients between water physical and chemical data (especially with the concentrations of phosphates and N-derived compounds) were obtained for the diatom index SPI and the IBMWP, though no biotic method detected changes in the concentrations of toxicants (Zn2+, Cr III). The use of diversity metrics as monitoring indices is not recommended. The results indicated that several different biotic indices, based on a wide range of biotic communities, must be integrated in water quality surveillance protocols, in order to reflect complementary aspects of the ecological status in river ecosystems.

En verano de 2005 se realizó un muestreo en 140 estaciones de la red ICA de la cuenca del Duero, a fin de determinar la calidad ecológica del agua en estos puntos utilizando diatomeas como bioindicadores. Los resultados muestran que el... more

En verano de 2005 se realizó un muestreo en 140 estaciones de la red ICA de la cuenca del Duero, a fin de determinar la calidad ecológica del agua en estos puntos utilizando diatomeas como bioindicadores. Los resultados muestran que el índice de diatomeas más apropiado para esta cuenca es el Índice de Poluosensibilidad Específica(IPS). Según este índice, el 61, 4% de los puntos alcanzan un estado ecológico de sus aguas "Bueno" o "Muy Bueno", cumpliendo con los objetivos determinados por la Directiva Marco del Agua. Sin embargo, el 38, 6% de los puntos no llegan a un nivel aceptable según dicho criterio.

Se propone un método para la toma de muestras de diatomeas epífitas en lagos y lagunas con el fin de aplicar dichas comunidades algales en la determinación del estado ecológico de estos sistemas acuáticos de acuerdo con los requisitos de... more

Se propone un método para la toma de muestras de diatomeas epífitas en lagos y lagunas con el fin de aplicar dichas comunidades algales en la determinación del estado ecológico de estos sistemas acuáticos de acuerdo con los requisitos de la Directiva Marco del Agua. La metodología se basa en el empleo de muestradores tipo Kornijów para la recolección del epifiton desarrollado sobre helófitos. Los resultados preliminares muestran la eficacia de este método en la evaluación de la calidad del agua. La aplicación de esta sencilla metodología permite el empleo de las diatomeas epífitas como indicadores biológicos de los medio lacustres, generando resultados reproducibles en el tiempo y basados en un protocolo común fácilmente aplicable.

Comparative morphological (including plastids) and ultrastructural (frustule) analyses of numerous taxa within the established diatom genus Neidium Pfitzer led to the conclusion that N. binodiforme Krammer and N. binodis (Ehrenberg)... more

Comparative morphological (including plastids) and ultrastructural (frustule) analyses of numerous taxa within the established diatom genus Neidium Pfitzer led to the conclusion that N. binodiforme
Krammer and N. binodis (Ehrenberg) Hustedt can be identified as striking exceptions. They would be more coherently allocated in a new freshwater benthic diatom genus, Neidiomorpha gen. nov. This proposed genus differs from Neidium mainly by the longitudinal structures (shallow “caves” in the mantle instead of distinct
canals at the junction between valve face and mantle), by areolation pattern (including the absence of renilimbi on the internal valve surface), and raphe endings (no silica flaps causing a bifurcate appearance of the polar endings and no central endings deflected towards opposing directions). Chloroplast number and arrangement (two valve- and girdle-appressed chloroplasts placed fore and aft in the two halves of the cell), overall valve outline, and ecology (preference for medium to high conductivity freshwaters) are likely to be further relevant distinctive elements. Observations on the distribution, and habitat and choriotope preference of the two species combined with the new genus are also provided.