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Diatomeas subfosiles del Lago Nahuel Huapi (Brazo Blest), Argentina García, M.L. & Maidana, N.I. Subfossil diatoms from Lago Nahuel Huapi (Brazo Blest), Argentina. The main objective of  this study was to analyze subfossil diatoms from Nahuel Huapi Lake (Brazo Blest) in order to increase the  knowledge about the region’s phycoflora, which until nowadays has been poorly studied. There were 47  genera and 114 infrageneric taxa recorded, from which 1 is recorded for first time for Argentina and 18 are  new records for Northern Patagonia (Argentina). DOI: https://botanicaargentina.org.ar/diatomeas-bacillariophyceae-subfosiles-del-brazo-blest-del-lago-nahuel-huapi-argentina/ Link: https://botanicaargentina.org.ar/diatomeas-bacillariophyceae-subfosiles-del-brazo-blest-del-lago-nahuel-huapi-argentina/

Little Ice Age to present paleoenvironmental reconstruction based on multyproxy analyses from Nahuel Huapi Lake (Patagonia, Argentina) Serra, M.N, García, M.L., Maidana, N.I, Villarosa,G., Lami, A. & Massaferro, J. Lakes are ideal sites to study environmental changes since they preserve climatic, anthropogenic, and volcanic signals in their sediments. Brazo Blest is one of the most important ramifications of Lake Nahuel Huapi and it is an interesting site to study climatic variations as it receives direct discharge of heavy suspended sediments loads from Tronador Glacier through the Frías River, as a result of the abrasion of the bedrock and runoff from the surrounding Valdivian Forest. A short sediment core from Brazo Blest was analyzed for chironomid and diatom assemblages and pigments in order to reconstruct environmental changes during the last 100 years in the basin under study. This multiproxy study also included geochemical and physical analyses and reveals changes ...

Staurosira patagonica sp. nov. a new diatom (Bacillariophyta) from Santa Cruz province, Argentina García, M.L., Maidana, N.I., Ector, L. & Morales, E.A This paper presents several Navicula sensu stricto species identified during a palaeocological study of a sediment core from Lake Miedwie in the vicinity of Szczecin, north-western Poland. Light microscopic examination of 91 samples revealed Navicula cari to be abundant as well as an unidentified diatom species corresponding to Navicula paracari, published by Lange-Bertalot as a manuscript name but not properly validated. A formal description of Navicula paracari is provided with a comparison to similar species including N. cari. Navicula cari is distinguished from N. paracari in having longer valves on average, lower stria density (distinguished with scanning electron microscopy) and by the presence of a prominent external sternum. Navicula microcari is mainly distinguished by distinctly narrower valves and a higher areola d...

Cocconeis neuquina Frenguelli (Bacillariophyta): emended description, lectotypification, ecology and geographical distribution.  García, M.L., Echazú, D.M. Romero O. E. & Maidana, N. I.  In this  article, we examine the type material of Cocconeis neuquina Frenguelli from the type locality in Neuquén province and other samples in southern Santa Cruz province (Patagonia, Argentina). Cocconeis neuquina is a small species with an oval-subcircular to broadly elliptical valve outline. The sternum valve is externally convex, striae are radiate and uniseriate, and areolae are rounded towards the mantle. The raphe valve is externally concave, the raphe is straight and filiform, striae are uniseriate, slightly radiate, and the first areola close to the mantle is drop-shaped. With this contribution we aim to clarify the morphology of this species, provide a more detailed description of valve ultrastructure, present its lectotypification and extend its geographical distributi...

Staurosirella andino-patagonica sp. nov. (Bacillariophyta) from lake sediments in Patagonia, Argentina Guerrero, J.M., García, M.L. & Morales, E.A. Staurosirella andino-patagonica, a new araphid diatom found in Holocene and recent surface sediments from lakes located in the Andes and adjacent steppe of Patagonia (Argentina), is described on the basis of light and scanning electron microscopy observations and comparison with related taxa. Although the elliptic valve outline of the new taxon resembles the smaller specimens of several Staurosirella species, ultrastructural features such as the presence of two spines on each virga and their distinct morphology -serrated with thickenings at the base- make Staurosirella andino-patagonica unique within the genus. Our study contributes to the knowledge of the Patagonian araphid diatom flora, a rather unexplored geographic area, and so we assume that, as additional areas are studied in detail, they will likely continue to yield new t...

Historical eruptions of Lautaro Volcano and their impacts on lacustrine ecosystems in southern Argentina Mayr, C., Smith, R.E, García, M.L., Massaferro, J., Lücke, A., Dubois, N., Maidana, N.I., Meier, W. J-H., Wissel, J. & Zolitschka Lacustrine sediment sequences were obtained from Lagunas Verde and Gemelas Este, two small lakes located east of the southern Patagonian Ice Field and close to the village of El Chaltén, in Argentinian Patagonia. Four tephra layers were identified in each of the short sediment sequences and characterised using individual glass-shard tephra chemistry to determine provenance. Bulk sediment geochemistry and diatom assemblages were analysed to understand the impact of the tephra deposits on the lake ecosystems. Age-depth models for the cores were established by 137Cs and 210Pb dating. Tephra deposits in Laguna Gemelas Este were dated to AD 1986–1998, 1943–1968, 1927–1955, and 1849–1892, and the tephra deposits in Laguna Verde were dated to AD 1940–...

Aulacoseira  species(Bacillariophyta) from the Argentinean Patagonia and re-examination of type material of Melosira perpusilla Frenguelli.  Phytotaxa 408 (3): 161-177.  García, M.L ., Morales, E.A., Guerrero, J.M., Tremarin, P.I. & Maidana, N.I. 2019. We present a detailed morphological analysis with light and scanning electron microscopy of two new small Aulacoseira species occurring in lacustrine sediments from small lakes in the provinces of Santa Cruz and Neuquén (Patagonia, Argentina). These species differ from similar taxa by unique combinations of characters. Aulacoseira lauquenensis sp. nov. can be differentiated by its broad collum, deep and solid ringleist and presence of short, spatulate and forked-tip spines. Aulacoseira liucoensis sp. nov. is distinguished by the presence of a marginal row of valve face areolae, straight mantle rows of coarse areolae, developed collum, protruding ringleist and conical, anchor-tip spines. Additionally, we re-ex...

A new species Pinnularia lacustrigibba sp. nov. within the Pinnularia subgibba group (Bacillariophyceae) Aloisie Poulíčková, Jan Kollár , Petr Hašler, Petr Dvořák & David G. Mann Some traditional diatom species have long been considered ‘cosmopolitan’, i.e., they are ubiquitous in suitable habitats. However molecular methods have revealed that some of these diatoms are complexes consisting of a few or many species, whose identification by eye with LM is difficult or impossible. This is true of several groups within Pinnularia , including the P. subgibba group, in which molecular species delimitation based on cox1-5P and D1–D3 LSU rDNA markers revealed 15 species within a dataset of 58 unique genotypes, representing 105 strains of the group. One clade comprises reproductively compatible clones from Scottish lakes and its morphology does not correspond exactly to any of the known Pinnularia species; thus the description of a new species ‘ P. lacustrigi...

A polyphasic approach to the delimitation of diatom species: a case study for the genus Pinnularia (Bacillariophyta) 2019 Jan Kollár , Eveline Pinseel , Pieter Vanormelingen, Aloisie Poulíčková, Caroline Souffreau, Petr Dvořák & Wim Vyverman Diatoms are one of the most abundant and arguably the most species‐rich group of protists. Diatom species delimitation has often been based exclusively on the recognition of morphological discontinuities without investigation of other lines of evidence. Even though DNA sequences and reproductive experiments have revealed several examples of (pseudo)cryptic diversity, our understanding of diatom species boundaries and diversity remains limited. The cosmopolitan pennate raphid diatom genus Pinnularia represents one of the most taxon‐rich diatom genera. In this study, we focused on the delimitation of species in one of the major clades of the genus, the Pinnularia subgibba group, based on 105 strains from a worldwide orig...

KAUPPILA, T., AHOKAS, T., NIKOLAJEV-WIKSTRÖM, L., MÄKINEN, J., TAMMELIN, M.H. & MERILÄINEN, J.J. 2016.  Aquatic effects of peat extraction and peatland forest drainage: a comparative sediment study of two adjacent lakes in Central Finland . Environmental Earth Sciences 75: 1473.  DOI: 10.1007/s12665-016-6278-x The aquatic effects of forestry practices and peat extraction continue to cause serious concerns. The effect mechanisms of peat extraction on water quality and aquatic ecology of the receiving surface waters are well known, but the impacts are often difficult to differentiate from those of forest management. A pairwise temporal sediment study was conducted on two adjacent lakes in Central Finland to study whether the unique effects of peat extraction can be detected in an area of intensive forest drainage. Both lakes are affected by forestry, but the reference lake has no history of peat extraction in its watershed. The deepest parts...

TAMMELIN, M. , KAUPPILA, T. & VIITASALO, M. 2017.  Factors controlling recent diatom assemblages across a steep local nutrient gradient in central-eastern Finland. Hydrobiologia . DOI: 10.1007/s10750-017-3229- 9 The Iisalmi Route, a chain of lakes in central-eastern Finland, is more eutrophic than its surroundings. We used multivariate analyses to study the influence of selected environmental factors (water quality, basin characteristics, and subcatchment surficial geology) on the recent diatom assemblages across this steep local nutrient gradient. In addition to the spatial analysis of surface sediment diatom assemblages from 51 sampling sites (48 lakes), temporal changes in the total phosphorus (TP) concentrations of one Iisalmi Route lake (Lake Kirmanjärvi) were analyzed using weighted averaging partial least squares regression and 27 fossil diatom samples. Both TP and electrical conductivity (EC) showed statistically significant indepe...

PINSEEL, E. , VAN DE VIJVER, B., KAVAN, J., VERLEYEN, E. & KOPALOVÁ, K. (2017).  Diversity, ecology and community structure of the freshwater littoral diatom flora of Petuniabukta (Spitsbergen).   Polar Biology  Despite the frequent application of diatoms in palaeoecological research in the High Arctic, our knowledge concerning the diversity, ecology, community associations, community dynamics and survival strategies of High Arctic freshwater littoral diatom floras is still rather limited. In the present study, the diversity, ecological characteristics and community structures of the freshwater littoral diatom flora from ponds and lakes of Petuniabukta (Spitsbergen, Svalbard Archipelago) were studied. In total, 87 samples from the littoral zone of 53 freshwater ponds and lakes were examined using light and scanning electron microscopy. A highly diverse diatom flora dominated by Achnanthidium and Nitzschia was observed. In total,...

VINSOVÁ, P., PINSEEL, E. , KOHLER, T.J., VAN DE VIJVER, B., ZARSKY, J., KAVAN, J. & KOPALOVÁ, K. (2015).  Diatoms in cryoconite holes and adjacent proglacial freshwater sediments, Nordenski [old glacier] (Spitsbergen, High Arctic).  Czech Polar Reports Cryoconite holes are small, extreme habitats, widespread in the ablation zones of glaciers worldwide. They can provide a suitable environment for microorganisms including bacteria, cyanobacteria, algae, fungi, and invertebrates. Diatoms have been previously recovered from cryoconite holes of Greenland and of Svalbard, and recent findings from Antarctica suggest that cryoconite holes may harbor a unique diatom flora distinct from other aquatic habitats nearby. In the present study, we characterize the diatom communities of Nordenskiöld glacier cryoconite holes in Billefjorden (Svalbard, Spitsbergen), and multivariate approaches were used to compare them with three freshwater localities in the immedi...

VOSSEL, H. ; REED, J. M.; HOUK, V.; CVETKOSKA, A. & VAN DE VIJVER, B. (2015). Cyclotella paleo-ocellata , a new centric diatom ( Bacillariophyta ) from Lake Kinneret (Israel). Fottea (15-1), 63-75 Large, subfossil populations of an unknown centric, planktonic diatom were observed in a lake sediment core from Lake Kinneret (Israel), which is here described as Cyclotella paleo–ocellata sp. nov. The new taxon, which belongs to the Cyclotella ocellata species complex, is described and separated from other similar taxa (e.g., Cyclotella ocellata , Cyclotella kuetzingiana , Cyclotella polymorpha , Cyclotella paraocellata ) based on a combination of the following morphological characters: valve diameter, number of orbiculi depressi (circular depressions), number of striae/10 μm, stria length, number and position of rimoportulae and the number of central and marginal fultoportulae. Cyclotella paleo–ocellata can be distinguished mainly by...

PINSEEL, E. , HEJDUKOVÁ, E., VANORMELINGEN, P., KOPALOVÁ, K., VYVERMAN, W. & VAN DE VIJVER, B. 2017.  Pinnularia catenaborealis sp. nov . ( Bacillariophyceae ), a unique chain-forming diatom species form James Ross Island and Vega Island (Maritime Antarctica).   Phycologia  A recent detailed survey of the Maritime Antarctic diatom flora using a fine-grained taxonomy resulted in the description of many new species of Pinnularia in general and the section Distantes, including the P. borealis species complex, in particular. Moreover, DNA-based studies of P. borealis revealed that many more species need to be described within this complex. During a survey of the freshwater littoral diatom flora of James Ross Island (Ulu Peninsula) and Vega Island in Maritime Antarctica, a previously unknown chain-forming species in the P. borealis species complex of section Distantes was cultured from three different localities. Molecular phylogen...

PINSEEL, E. , VAN DE VIJVER, B. & KOPALOVÁ, K. 2015.    Achanthidium petuniabuktianum sp. nov. ( Achnanthidiaceae, Bacillariophyta ), a new representative of the  A. pyrenaicum  group from Spitsbergen (Svalbard, Archipelago, High Arctic).   Phytotaxa  During a survey of the freshwater littoral diatom flora from lakes and ponds in the region of Petuniabukta on Spitsbergen (Svalbard Archipelago, High Arctic region), a new Achnanthidium species, A . petuniabuktianum sp. nov., has been recorded. Achnanthidium petuniabuktianum is a new representative of the A . pyrenaicum group as evidenced by its curved distal raphe fissures. The present paper describes in detail the morphology of A . petuniabuktianum based on light and scanning electron microscopy. The new taxon is characterized in having linear valves with parallel margins and broadly rounded, never protracted apices and a characteristic—in light microscopy hardly dis...

PINSEEL, E. , KOPALOVÁ, K. & VAN DE VIJVER, B. 2014.    Gomphonema svalbardense  sp. nov, a new freshwater diatom species from the Arctic Region.  Phytotaxa  During a survey of freshwater diatoms from lakes in the region of Petuniabukta on Spitsbergen (Svalbard Archipelago) a new Gomphonema species, G. svalbardense sp. nov., has been recorded. The new taxon was previously cited in the literature as G. angustatum var. undulatum but this identification proved to be erroneous. Detailed morphology description of G. svalbardense based on light and scanning electron microscopy is presented in this paper and the morphological features of the taxon have been compared with similar species. Gomphonema svalbardense is characterized by its typical linear, almost naviculoid outline with undulating margins, with clearly inflated central part,  asymmetric central area, lateral raphe with simple straight proximal endings and the weakly radiate str...

PINSEEL, E. , VANORMELINGEN, P., HAMILTON, P.B., VYVERMAN, W., VAN DE VIJVER, B. & KOPALOVÁ K. 2017.  Molecular and morphological characterization of the Achnanthidium minutissimum complex (Bacillariophyta) in Petuniabukta (Spitsbergen, High Arctic) including the description of A. digitatum sp. nov.   European Journal of Phycology   Recent morphology-based investigations of freshwater Arctic diatoms suggest that many species remain to be discovered, reflecting a unique polar flora. During a survey of the freshwater diatom flora of northern Billefjorden, including the Petuniabukta fjord region (Spitsbergen), several morphodemes belonging to the Achnanthidium minutissimum species complex were recorded. Molecular phylogenies based on rbc L, 28S and 18S sequences, including single cells from Canada and strains from Marion Island (sub-Antarctica) and GenBank revealed the presence of 12 distinct A. minutissimum complex lineages, of which t...

  CARBALLEIRA, R., TROBAJO, R., LEIRA, M.,  BENITO, X ., SATO, S. & MANN D.G. 2017.   A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae.   European Journal of Phycology .  A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia . Molecular phylogenies based on rbc L and LSU rDNA indicated, however, that the new species does not belong in Hantz...

(image from here ) ALMEDIA, P., WETZEL, C., MORALES, E.A, ECTOR, L., BICUDO, D.E. 2017.  New species and combination of Fragilarifoma (Bacillariophyta) from tropical freshwater environments. Fottea , 17: 277-292. Several species currently belonging to the genus Fragilariforma D.M. Williams et Round are known worldwide. This genus is mainly characterized by regular spacing of the uniseriate striae composed of round areolae bearing simple vela, and simple apical pore fields. A large number of species has been recognised for some regions of South America and tropical Africa, but few studies encompass type material and/or the morphological variation existing within populations of the different species. The aim of this study is to identify and describe the morphology of these species from tropical environments under light and scanning electron microscopy and using available type material. Nomenclatural issues are examined and clarified for five taxa: Fragi...