Marina Potapova

• Drexel University

The online diatom identification and ecological assessment guide, Diatoms of North America (https://diatoms.org), provides taxonomic, nomenclatural, and ecological information on over 1000 diatom species to date (Spaulding & al. 2021). In creating and maintaining species pages for the website and in supporting efforts to achieve taxonomic certifica...

Microscopic eukaryotes are important components of coastal wetland ecosystems. The goal of this study was to investigate the diversity of microeukaryotes in the tidal pools of a New Jersey salt marsh and to compare the assemblages of natural and artificial pools excavated for controlling mosquito populations. We evaluated microeukaryotic assemblage...

A new species of Aulacoseira Thwaites is described from sediment deposits of Surprise Lake, an isolated lake located in the New Jersey Highlands. The species is characterized by (1) a low mantle, (2) unevenly distributed mantle areolae of variable size and shape, and (3) a valve face covered by rounded areolae. The new species is most similar to Au...

During the warm middle Eocene (ca 45 Ma), the Napartulik area (also called “the Geodetic Hills”), Axel Heiberg Island, northern Canada (Nunavut), was vegetated with mixed broad-leaved deciduous angiosperm and evergreen conifer forests over extensive floodplain and forested wetland habitats. Massive organic rich sedimentary successions and encapsula...

Sediment diatoms are widely used to track environmental histories of lakes and their watersheds, but merging datasets generated by different researchers for further large-scale studies is challenging because of taxonomic discrepancies caused by rapidly evolving diatom nomenclature and taxonomic concepts. We collated five datasets of lake sediment d...

Stauroneis terryi D.B. Ward ex T.C. Palmer is a diatom so far reported from only five locations in the states of Connecticut, Massachusetts and Maine, USA, where it was collected in 1890—1911. There were no records of this large and rather conspicuous species in any collections made after 1911 despite the considerable number of diatom surveys and p...

Consistent identification of diatoms is a prerequisite for studying their ecology, biogeography, and successful application as environmental indicators. However, taxonomic consistency among observers has been difficult to achieve because taxonomic information is scattered across numerous literature sources, presenting challenges to the diatomist. F...

DNA metabarcoding is rapidly expanding as a new approach to biodiversity assessments and biomonitoring and is especially valuable for characterizing microbial communities in aquatic habitats. When applied to eukaryotic organisms, metabarcoding is usually targeting specific taxonomic groups, such as macroinvertebrates, fungi, diatoms, or other proti...

Cyclotella lacuskarluki Manguin ex Kociolek & Reviers is a small diatom known only from the original drawing that provides little information on the morphology of this taxon. As Manguin's original materials are lost, recently collected samples from Lake Karluk, Alaska, the type locality of the species, were studied with light and scanning electron...

The genus Krsticiella Levkov was previously known only from the basins of Lakes Ohrid and Prespa, and from Lake Baikal. Examination of type materials of diatoms originally described by Niels Foged from the North Slope of Alaska revealed that Navicula lenis Foged and N. meadeensis Foged belong to Krsticiella, to which they are formally transferred h...

Background and aims – A novel species of Navicula has been recently discovered in rivers of the central Appalachian Mountains, USA. The purpose of this paper is to formally establish this new species and to determine whether it had been overlooked in the past or is a recent arrival to the area. Methods – We studied historical collections made in Pe...

Diatoms have been successfully used as indicators of past and present environmental conditions in freshwater and marine habitats, but their diversity and indicative properties in microtidal coastal wetlands of temperate zone are relatively poorly studied. The goal of this study was to determine whether diatoms can be used as indicators of sea level...

Three rare Psammothidium species were found in recently surveyed lakes of Northeastern Siberia, Russia. One of these species found in lakes of the Kolyma Lowland, is new for science and is formally described here as Psammothidium onufrii sp. nov. It is morphologically similar to the brackish-water species Achnanthes punctulata, but it lacks a centr...

Desianti, N.; Potapova, M.; Enache, M.; Belton, T.J.; Velinsky, D.J.; Thomas, R., and Mead, J., 2017. Sediment diatoms as environmental indicators in New Jersey coastal lagoons. In: Buchanan, G.A.; Belton, T. The goal of this study was to explore the possible use of sediment diatoms as environmental indicators in New Jersey coastal lagoons. Diatom...

Two new species of Gomphonema with linear-lanceolate valves, narrow cells (width ≤6 µm), wide axial areas, short uniseriate striae, and one stigmoid per valve are described. Gomphonema caperatum sp. nov. has narrow, almost linear valves with short marginal striae, apically elongated slit-like areolae, and transapically oriented linear markings on t...

Aim Establishing the distribution and diversity of populations in the early stages of invasion when populations are at low abundance is a core challenge for conservation biologists. Recently, genetic monitoring for environmental DNA (e DNA ) has become an effective approach for the early detection of invaders, especially for microscopic organisms w...

In support of efforts to reconstruct relative sea level (RSL), we investigated the utility of foraminifera, diatoms and bulk-sediment geochemistry (δ13C, C:N and parameters measured by Rock-Eval pyrolysis) as sea-level indicators in Eurasian sub-Arctic salt marshes. At three salt marshes (<15 km apart) in Dvina Bay (White Sea, Russia), we collected...

Catalogue of diatom names resurrected: diatombase will be the new authority resource for diatom names and more.

Sediment samples from the coastal lagoons and estuaries of New York and New Jersey were used to investigate the influence of contaminants on diatom assemblages. Multivariate analyses demonstrated correspondence between composition of diatom assemblages and concentrations of several metals and total PAH. The effects of the individual contaminants we...

Two species of Navicula—N. volcanica and N. subwalkeri—are described as new based on LM and SEM observations and a comparison with similar species. Modern distributions of the new species are restricted to two adjacent headwater streams along the crest of the Cascade Mountains in western Oregon, USA. Both species are established as extant based on...

In 1966, Matthew Hohn and Joan Hellerman described 44 diatom species from one freshwater and several coastal habitats along the Atlantic coast of the USA. The goal of our study was to examine the type materials of these species and to evaluate their taxonomic status. Type specimens of 32 taxa were located and documented with light microscopy, and o...

Cavinula Mann & Stickle is small genus presently comprising 25 taxa distinguished by the linear to round-elliptical valve shape, uniseriate striae, presence of nodules and distinctive terminal pores. Most often the species from the genus have been reported from colder northern or alpine oligotrophic aquatic systems, or moist sub-aerial habitats. Ob...

Cavinula Mann & Stickle is small genus presently comprising 25 taxa distinguished by the linear to round-elliptical valve shape, striae, presence of nodules and distinctive terminal pores. Most often the species from the genus have been reported from colder northern or alpine oligotrophic aquatic systems, or moist sub-aerial habitats. Observation o...

A new species of Encyonema was found in several rivers and reservoirs in Western Pennsylvania, USA, in 2013. The new species, E. appalachianum, has only very slightly dorsiventral valves, which is one of the characters separating the genus Encyonopsis from Encyonema. On the other hand, the long, sharply bent terminal raphe fissures and lateral raph...

A new species, Platessa strelnikovae Enache, Potapova & E.Morales is described from modern and subfossil lake sediments from the Northeastern United States. This species is placed in the genus Platessa Lange-Bertalot based on biseriate striae and absence of terminal raphe fi ssures. The new species is easily distinguishable from other Platessa spec...

Stauroneis pachycephala was described in 1881 from the Baakens River, Port Elizabeth, South Africa. Recently, it was found during surveys of the MacKenzie River (Victoria, Australia), the Florida Everglades (USA) and coastal marshes of Louisiana (USA). The morphology, ecology and geographic distribution of this species are described in this article...

Surirella arctica comb. et stat. nov. (Bacillariophyta)—a rare arctic diatom Abstract Surirella terryi var. arctica has been described more than 50 years ago from northern Alaska. Since then, it has not been reported in the scientific literature except for a single record. We studied in detail the holotype slide and material of S. terryi var. arcti...

The examination of a moss sample collected from a lake in a remote mountainous region of Eastern Siberia revealed a diverse diatom flora that included four new species: Eunotia frigida, Brachysira subtile, Encyonopsis vasilievae, and Neidium rugosum. N. rugosum has been previously illustrated from several locations in the arctic and subarctic and i...

The goal of this study was an inventory of diatoms of Bering Island, the largest of the Commander Islands located east of Kamchatka Peninsula, Russia. Diatom samples were collected in summer 2008 from 85 sites, mostly from ponds, small lakes, rivers, and streams. A total of 313 species and infraspecifi c diatom taxa were found. The diatom fl ora of...

A new species, Platessa strelnikovae Enache, Potapova & E.Morales is described from modern and subfossil lake sediments from the Northeastern United States. This species is placed in the genus Platessa Lange-Bertalot based on biseriate striae and absence of terminal raphe fi ssures. The new species is easily distinguishable from other Platessa spec...

Surirella cruciata A. Schmidt and S. terryi Terry are rare and poorly known diatom species originally described from North America and previously illustrated only by drawings. The goal of this study was to examine and document the morphology and distribution of these species. First photographs designating the lectotype of S. terryi and the neo- and...

Populations of several Psammothidium species were found in core sediments from nine remote, high elevation, ultraoligotrophic and oligotrophic, Olympic and Cascade Mountain lakes. Three of these species, P. lacustre, P. alpinum, and P. nivale, are described here as new. The morphology of the silica frustules of these species was documented using li...

Achnanthes decipiens Reimer was described from a benthic sample collected from a small stream in South Carolina, USA. Examination of the type material with light and electron microscopy showed that this species belongs to the genus Nupela Vyverman & Compère to which it is transferred. Nupela decipiens (Reimer) Potapova is similar to N. praecipua (R...

Type material of the diatom species Eunotia arcuoides Foged, housed at the ANSP Diatom Herbarium and at the Natural History Museum of Denmark, is investigated with light and electron microscopy, and a lectotype specimen of this species is designated. Eunotia arcuoides is a poorly known species that shares a number of morphological characters with a...

The goal of this study was to investigate type materials of 22 Navicula species described by Ruth Patrick in 1959. Type specimens of two species could not be found on the holotype slides. The holotypes of 20 other taxa were located and imaged. Specimens of 11 taxa from type materials or from the type localities were investigated with electron micro...

A new diatom species, Eucocconeis americana, is described from eastern North America. The new species differs from previously reported representatives of Eucocconeis Cleve by relatively flat valves and the characteristic shape of the central areas in both raphe and rapheless valves. We present details on the frustule structure and size variation, a...

Abstract. Stream indicators used to make assessments of biological condition are influenced by many possible sources of variability. To examine this issue, we used multiple-year and multiple-reach diatom, fish, and invertebrate data collected from 20 least-disturbed and 46 developed stream segments between 1993 and 2004 as part of the US Geological...

This article clarifies the taxonomy and nomenclature of several monoraphid diatom species found in rivers and lakes of North America. The morphology of these diatoms is studied with light and electron microscopy. A new combination Rossithidium anastasiae (Kaczmarska) Potapova is introduced for a species common in both Europe and North America and o...

The morphology and ontogenetic allometric trends of several taxa in the Pinnatae group of Surirella were studied using traditional morphometrics, landmark-based shape analysis, and light and electron microscopy. We investigated separately two groups of species: the first consisted of S. brebissonii Krammer & Lange-Bertalot, S. brebissonii var. kuet...

A new diatom species, Tabellaria vetteri, is described from North-Central Pennsylvania. Unlike other representatives of the genus Tabellaria Ehrenberg, the new species lacks rimoportulae, the central part of its valve is internally thickened, and all girdle bands are open. Other characters, such as shape of the frustule, numerous ligulate girdle ba...

The total concentration of dissolved salts and the ionic composition of water are known to be important ecological factors influencing diatom distribution. The difference in salt content between marine and inland waters has been regarded as a major boundary that only a few diatom lineages managed to cross and in only one direction, from marine to f...

Several species of Nupela were found in samples collected in 2009 from streams and aerophytic habitats of North-central Pennsylvania. Some of these species appeared either new to science or insufficiently known and, although described earlier, not yet transferred to the genus Nupela. This triggered an investigation of type materials of several Nupe...

Dr. Charles W. Reimer dedicated almost 50 years of his life to the development and maintenance of the ANSP Diatom Herbarium. Today this is one of the largest diatom collections in the World. Its holdings include many historic and taxonomically important collections of prominent diatomists. Extensive collections of diatoms from river, lake, and wetl...

Diatom identification guide & ecological resource for water resource managers, ecologists, taxonomists, analysts, systematists, students, and the public. http://westerndiatoms.colorado.edu/

A new small-size species of Sellaphora was found in sediments from Hannaberry Lake, Arkansas, during the National Lakes Assessment project conducted by the United States Environmental Protection Agency. The species was studied with light microscopy and scanning electron microscopy. It differs from previously reported Sellaphora species by its small...

A new small-size species of Sellaphora was found in sediments from Hannaberry Lake, Arkansas, during the National Lakes Assessment project conducted by the United States Environmental Protection Agency. The species was studied with light microscopy and scanning electron microscopy. It differs from previously reported Sellaphora species by its small...

Selected Sellaphora species from rivers and springs of the southeastern United States were studied by light (LM) and scanning electron (SEM) microscopy. Three new species are described here and two new combinations are made. Besides the traditional morphological characters, additional morphometric data were used to delineate species. Sellaphora hoh...

The heavily silicified and coarsely ornamented Aulacoseira canadensis (Hustedt) Simonsen and Aulacoseira crassipunctata Krammer are morphologically similar and often confused in collections from North America. Re-examination of samples and permanent slides from several collections derived from biological monitoring and research programs allowed Lis...

We studied how size variation in populations of Diatoma moniliformis Kütz. was influenced by environmental effects on the diatom life cycle. One of the two populations sampled monthly in the northern Baltic Sea grew under natural conditions; the other population was in a cooling water discharge channel of a nuclear power plant, where the temperatur...

We developed empirical models for fish, macroinvertebrate, and diatom assemblages to assess the biological condition of 268 streams sampled from 1993 to 2002 in 7 major river basins in the Appalachian region of the USA. These models estimate the expected taxonomic composition at each site based on observed variation in taxonomic composition at refe...

Diatoms from the genus Achnanthidium are abundant in rivers, streams, and springs of the Appalachian Mountains. They inhabit clean and polluted waters, including those affected by acid mine drainage. The identification of Achnanthidium taxa is difficult due to their small cell size and insufficient information in the diatom floras. We studied the t...

Variation of frustular morphology within the Achnanthidium minutissimum (Kütz.) Czarn. species complex was studied in type populations of 12 described taxa and in 30 recent North American river samples. The SEM observations in this study and other publications showed that ultrastructural characters on their own do not discriminate among taxa within...

Two major arguments in favor of using diatoms in water-quality assessments are that their distributions are cosmopolitan and their ecology is well studied. If these assumptions are true, diatom-based monitoring tools could be considered universal and used in any geographic area. Indeed, some diatom metrics based on species indicator values develope...

Achnanthidium zhakovschikovii is described as a new epiphytic species from spring-fed rivers near St. Petersburg, Russia. This species belongs to the group of Achnanthidium taxa with terminal raphe fissures curved to one side of the valve. The new species differs from other taxa in this group by the broadly linear to elliptical shape of the valve a...

Our study investigated whether algae-based water-quality assessments are affected by differences between algal assemblages on hard substrates (rocks, wood) and soft substrates (fine- grained sediments). We analyzed a US Geological Survey National Water-Quality Assessment (NA- WQA) program data set that consisted of 1048 pairs of samples collected f...

Patterns of stream benthic algal assemblages along urbanization gradients were investi-gated in three metropolitan areas—Boston (BOS), Massachusetts; Birmingham (BIR), Alabama; and Salt Lake City (SLC), Utah. An index of urban intensity derived from socioeconomic, infrastruc-ture, and land-use characteristics was used as a measure of urbanization....

Two species of Achnanthidium, which are fairly common in benthic samples collected from North American rivers, have posed considerable identification problems for analysts enumerating diatoms for water quality assessment programs in the United States. Both diatoms belong to the apparently diverse and insufficiently studied group of Achnanthidiumspe...

This study compares two approaches for constructing diatom-based indices for monitoring river eutrophication. The first approach is based on weighted averaging of species indicator values with the underlying assumption that species have symmetrical unimodal distributions along the nutrient gradient, and their distributions are sufficiently describe...

Three small-celled Nupela species were found in streams and moist habitats of the United States, with a concentration of locations in the eastern part of the country. Two new species are described here: N. neglecta Ponader, Lowe & Potapova and N. Carolina Potapova & Clason. These two species and Nupela wellneri (Lange-Bertalot) Lange-Bertalot have...

We quantified the relationships between diatom relative abundance and water conductivity and ionic composition, using a dataset of 3239 benthic diatom samples collected from 1109 river sites throughout the U.S.A. [U.S. Geological Survey National Water‐Quality Assessment (NAWQA) Program dataset]. This dataset provided a unique opportunity to explore...

The large variation in size and shape in diatoms is shown by morphometric measurements of 515 benthic and pelagic diatom species from the Baltic Sea area. The largest mean cell dimension (mostly the apical axis) varied between 4.2 and 653 μm, cell surface area between 55 and 344,000 μm2, and cell volume between 21 and 14.2 × 106μm3. The shape-relat...

Aim To study large‐scale patterns of benthic diatom assemblages in rivers, to assess the relative importance of environmental and geographical factors affecting their composition, and to evaluate the implications of these patterns for the use of diatoms as indicators of water quality, particularly nutrient enrichment. Location The United States Ge...

Taxa belonging to the genus Diatoma (Bacillariophyta) are dominants in the northern Baltic Sea (<6‰ salinity). In spring, millions of cells per cm2 of D. moniliformis are found along the whole Gulf of Bothnia coast for hundreds of kilometres. In the present study phenotypic variation and distribution of 52 Diatoma populations from the Baltic Sea we...

Epilithic algal communities were studied at 84 sites situated in 48 streams and rivers of the Kolyma Mountains; NE Siberia, Russia. The 62 most abundant algal species were mainly typical inhabit ants of nutrient-poor, fast-flowing waters of mountainous and high-latitude regions. Canonical Correspondence Analysis showed that differences in the flow...

Volume 3 in a series which has resulted from a joint intercalibration programme of the Baltic Marine Biologists (BMB) Working Group 27. Each species is illustrated with a photograph and extensive references to the appropriate up-to-date information literature. This book can be ordered from http://www.nhbs.com and other internet book stores. In vol...