New Diatom Species Research Articles

Buryatia strelnikovae (Bacillariophyta), a New Species of Diatoms for Science

The study of algological material from tundra lakes of the adjacent territories of the Ust-Lena Reserve (Yakutia) using scanning electron microscopy revealed a new species of diatoms for science Buryatia strelnikovae sp. nov. The new species has morphological similarities with other species of the genus B. oviformis and B. crassa. It differs from the former by large values of the number of striae and areolae of 10 µm, from the latter by smaller length and width of the sash and large values of the number of strokes and areoles of 10 µm, but differs from them in smaller leaf length and width, large values of the number of striae and areolae of 10 µm.

Entomoneis parikhani sp.nov., Aras Nehri (İran)’nden yeni bir diatom (Entomoneidaceae, Bacillariophyta)

The diatom Entomoneis has a series of unique features such as connecting lines with different shapes, sigmoid raphe on the bilobate keel, different curtains, and multiple girdle bands. Most species belonging to this genus are found in marine and saline habitats. In fact, the genus Entomoneis is an epipelic diatom that is found in streams with high salinity and high electrolyte concentration. To date, no specific type of freshwater has been identified for this species. In this study, a new species of freshwater diatom, Entomoneis parikhani, is described based on detailed morphological observations using a scanning electron microscope. The samples were collected the Aras River near Oltan village of Parsabad city in the northwest Iran. A special feature of Entomoneis parikhani is its triple valve. The genus Entomoneis comprises of diatoms with sigmoidal raphe canals and girdle bands. This taxon is similar to Entomoneis annagodhei and Entomoneis tenera, as shown by LM and SEM observations, and there are sufficient morphological differences to separate Entomoneis parikhani. This new species had very small cells, delicate frustules without valve lines, and wide lanceolate valves. In this study, the wide distribution of this taxon in the Aras River has been evaluated.

Description of Amphorotia robusta sp. nov. (Bacillariophyceae) from the Pearl River System, China

A new species of diatom, Amphorotia robusta sp. nov., is described from subaquatic sediments in the Lingding estuary and Pearl River delta, China. It is distinctive in having strongly curved valves, and regularly even-spaced stria arrangement on both ventral and dorsal sides of the valve. This study builds upon previous diatom research conducted in the Pearl River delta and contributes to our understanding of the taxonomy of the genus Amphorotia in southeastern China. Consequently, it highlights this region as one of the most ecologically diverse habitats for the genus Amphorotia in the Southeast Asian region.

Pseudogomphonema lukinicum sp. nov. (Bacillariophyceae), a new endophytic diatom found inside multicellular red algae from the Northwest Pacific

Abstract In our collections from the Northwest Pacific waters, we found several specimens of the red algae Lukinia dissecta and Callophyllis perestenkoae with darker spots on their thalli, which contained an unusual pennate diatom. A detailed morphological analysis based on light and scanning electron microscopy observations made it possible to describe a new species of endophytic diatom, Pseudogomphonema lukinicum sp. nov. Stonik et Skriptsova. The new species has some morphological features typical of the genus, such as the heteropolarity of the valves, the presence of pseudosepta and small apical chambers at both poles of the valves, and nonporous girdle bands. Pseudogomphonema lukinicum has been described and distinguished from the other species in the genus on the basis of a combination of morphological traits, including relatively small cell dimensions, a slightly asymmetrical valve to the transapical axis, with obtusely rounded headpole and narrower footpole, the large asymmetrical central area, and the presence of apical chambers at both poles. Pseudogomphonema lukinicum is the second representative of Pseudogomphonema known to be living endophytically. The data on the species composition of endophytic diatoms in marine macroalgae, their habitats, and host organisms reported in the literature to date are summarized.

Description of Naviculavanseea sp. nov. (Naviculales, Naviculaceae), a new species of diatom from the highly alkaline Lake Van (Republic of Türkiye) with complete characterisation of its organellar genomes and multigene phylogeny.

The current article describes Naviculavanseeasp. nov., a new species of diatom from Lake Van, a highly alkaline lake in Eastern Anatolia (Türkiye). The description is based on light and scanning electron microscopy performed on two monoclonal cultures. The complete nuclear rRNA clusters and plastid genomes have been sequenced for these two strains and the complete mitogenome for one of them. The plastome of both strains shows the probable loss of a functional ycf35 gene. They also exhibit two IB4 group I introns in their rrl, each encoding for a putative LAGLIDADG homing endonuclease, with the first L1917 IB4 intron reported amongst diatoms. The Maximum Likelihood phylogeny inferred from a concatenated alignment of 18S, rbcL and psbC distinguishes N.vanseea sp. nov. from the morphologically similar species Naviculacincta and Naviculamicrodigitoradiata.

Theoretical and Experimental Studies on the Evidence of 1,3-β-Glucan in Marennine of Haslea ostrearia.

Marennine, a blue pigment produced by the blue diatom Haslea ostrearia, is known to have some biological activities. This pigment is responsible for the greening of oysters on the West Coast of France. Other new species of blue diatom, H. karadagensis, H. silbo sp. inedit., H. provincialis sp. inedit, and H. nusantara, also produce marennine-like pigments with similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms present a commercial potential for the aquaculture, food, cosmetics, and health industries. Unfortunately, for a hundred years, the exact molecular structure of this bioactive compound has remained a mystery. A lot of hypotheses regarding the chemical structure of marennine have been proposed. The recent discovery of this structure revealed that it is a macromolecule, mainly carbohydrates, with a complex composition. In this study, some glycoside hydrolases were used to digest marennine, and the products were further analyzed using nuclear magnetic resonance (NMR) and mass spectroscopy (MS). The reducing sugar assay showed that marennine was hydrolyzed only by endo-1,3-β-glucanase. Further insight into the structure of marennine was provided by the spectrum of 1H NMR, MS, a colorimetric assay, and a computational study, which suggest that the chemical structure of marennine contains 1,3-β-glucan.

Morphology and molecular phylogeny of Pleurosigmapacificum sp. nov. (Pleurosigmataceae), a new tropical pelagic species from the Western Pacific Ocean.

A new species of pelagic diatom, Pleurosigmapacificumsp. nov., is described from the tropical Western Pacific Ocean. It has the typical features of Pleurosigma, including a slightly sigmoid raphe, intersected transverse and oblique striae, and loculate areolae with external opening slits and internal poroids. Morphologically, P.pacificum belongs to a species group of Pleurosigma with lanceolate valves, including P.atlanticum Heiden & Kolbe, P.nubecula W. Smith, P.indicum Simonsen, and P.simonsenii Hasle. However, P.pacificum differs by its smaller lanceolate valve and smaller intersection angle as well as elliptical areolae without a silica bar. The SSU rDNA and rbcL sequence data place P.pacificum in a basal position relative to other species of Pleurosigma. Our molecular phylogenetic analyses did not support the monophyly of lanceolate and slightly sigmoid species. Thus, the sigmoidality of valve outline cannot be considered as a criterion to define the species group.

New Representative of the Genus <i>Aulacoseira</i> (Bacillariophyta) from Chukotka (Russia)

A new species of diatoms, Aulacoseira сhukotkaensis sp. nov., has been described using scanning electron microscopy. The new species has morphological similarity to other Aulacoseira taxa but can be distinguished from A. alpigena by the number of rows of areolae in 10 µm and the length and shape of spines, from A. helvetica by the valve height and the number of areolae rows in 10 µm, and from A. pardata by the shape of spines and the number of rows of areolae in 10 µm.

Fragilaria odeloucaensis sp. nov. (Bacillariophyta, Fragilariaceae) a diatom from temporary streams in southern Portugal

A new species of araphid diatom is described from a temporary stream in southern Portugal, Fragilaria odeloucaensis sp. nov., which belongs to the group of Fragilaria with widely linear to lanceolate valve outline, spaced striae, lacking spines, and with well-developed apical pore fields. The new taxon can be distinguished based on five unique features within this group, the lanceolate valves with capitate apices, the zig-zagged axial area, the central area with squared fascia, the apical pore fields clearly sunken into the valve apices and the heterovalvar frustules (with respect to striae distancing). Ecological features of the type locality and an additional sampling point where the new species was found are given, together with a discussion of the taxonomic position of the new species within Fragilaria, and the approach used herein for the identification of diagnostic features. This approach includes a detailed analysis of the internal and external characteristics of the axial area-virgae-striae complex, central area, apical pore fields and differences among valves of the same frustule, in addition to the traditional valve shape and morphometric features.

An unusual freshwater diatom with bilobate ends from the Mid-Miocene of East Antarctica: Staurosirella tigris sp. nov. (Fragilariaceae, Bacillariophyta)

A new species of araphid diatoms with bilobate ends is described as Staurosirella tigris sp. nov. It was found in mid-Miocene glacial-lacustrine sediments in the Friis Hills, Antarctica. The new diatom is placed in Staurosirella because it has striae composed of apically-oriented lineolae, separated by long, thin vimines, and it lacks rimoportulae. It can be easily distinguished by its rectangular valve shape with bilobate ends, differing from Staurosirella grunowii, another four-lobed Miocene species, by having a rectangular central portion to its valves instead of being cross-shaped with the four lobes arising from a common central area. Also, the distribution of the new species is different, to date only being found in Antarctica, while S. grunowii is restricted to the Northern Hemisphere.

New species of benthic marine diatoms (Bacillariophyta) from the Western Pacific islands of Guam and Yap

In the course of preparation of a major checklist for Yap and ongoing investigations into the benthic marine diatom flora of Micronesia, thirteen new araphid and raphid pennate diatom species have been recognized and are described here. Plagiogramma subatomus is even smaller than P. atomus and the pseudoseptum forms a box with only a small opening toward the cell interior. Licmophora romuli is similar in size and spathulate shape to L. remulus, but the majority of the striae in the lamina lack vimines. L. graphis is exceedingly delicate, pencil-shaped, with apical striae 60–70 in 10 µm. Divergita biformis and D. decipiens are straight species with striae biseriate on the margin, uniseriate on the valve face, differing in the shape and prominence of the sternum and the shape of the valve-face areolae. D. macinnisii (from Marshall Islands, but included here for comparison) is curved, again with the decussate areolar pattern on the mantle, but with single extended areolae along each side of the linear sternum. These characters slightly amend the diagnosis of the genus. Thalassionema baculum is a very short member of the genus, linear and isopolar. Climaconeis tarangensis is curved and differs from C. riddleae in stria density and areola shape; C. minaegensis is straight, without a stauros or craticular bars, of intermediate length, 228–247 µm. First SEM observations of Climaconeis lorenzii are presented and an updated key to Climaconeis is appended. Parlibellus paschalis is a tube-dwelling species differing from P. delognei is lacking cuniculi and pores in the central area. P. waabensis is a relatively large species, possibly tube-dwelling, that differs from P. delognei in shape and spacing of central striae and from P. berkeleyi in width and stria density. Pleurosigma simulacrum differs in ultrastructural details from P. intermedium. Lastly, Nitzschia tarangensis is a conopeate species, spathulate in profile with ribs along the edge of the valve depression and bordering the raphe, and with pores in the peri-raphe zone.

Haslea silbo, A Novel Cosmopolitan Species of Blue Diatoms.

Specimens of a new species of blue diatoms from the genus Haslea Simonsen were discovered in geographically distant sampling sites, first in the Canary Archipelago, then North Carolina, Gulf of Naples, the Croatian South Adriatic Sea, and Turkish coast of the Eastern Mediterranean Sea. An exhaustive characterization of these specimens, using a combined morphological and genomic approach led to the conclusion that they belong to a single new to science cosmopolitan species, Haslea silbo sp. nov. A preliminary characterization of its blue pigment shows similarities to marennine produced by Haslea ostrearia, as evidenced by UV-visible spectrophotometry and Raman spectrometry. Life cycle stages including auxosporulation were also observed, providing data on the cardinal points of this species. For the two most geographically distant populations (North Carolina and East Mediterranean), complete mitochondrial and plastid genomes were sequenced. The mitogenomes of both strains share a rare atp6 pseudogene, but the number, nature, and positions of the group II introns inside its cox1 gene differ between the two populations. There are also two pairs of genes fused in single ORFs. The plastid genomes are characterized by large regions of recombination with plasmid DNA, which are in both cases located between the ycf35 and psbA genes, but whose content differs between the strains. The two sequenced strains hosts three plasmids coding for putative serine recombinase protein whose sequences are compared, and four out of six of these plasmids were highly conserved.

New fossil genus and new extant species of diatoms (Stephanodiscaceae, Bacillariophyceae) from Pleistocene sediments in the Neotropics (Guatemala, Central America): adaptation to a changing environment?

Several taxa of Stephanodiscaceae were found in the upper section of Pleistocene sediments from Lake Petén-Itzá (Guatemala). A new fossil genus Cyclocostis Paillès gen. nov. and new extant species Discostella gabinii Paillès & Sylvestre sp. nov. are described. Cyclocostis gen. nov. is characterized by a strongly tangentially undulated valve surface, coarse unequal striation reaching a central punctum in the valve center, an absence of central lamina and domed criba, widely open alveoli with one median recessed costa bearing marginal fultoportulae and a single rimoportula all within a ring. A single valve face fultoportula is present on the raised part of the valve opposite the rimoportula. Differences relative to similar genera and the delimitation of a new genus are discussed. Discostella gabinii sp. nov. is distinguished by circular and flat valves, a small central area bearing 5 to > 30 scattered large areolae giving a colliculate appearance, medium-sized alveoli, marginal fultoportulae on every 4–5th costa, a single rimoportula and internally smooth valve center. Differences to similar taxa in the genus Discostella are discussed. The succession of the species of Cyclotella, Discostella and Cyclocostis gen. nov. in our record could represent eco-phenotypic responses to particular environmental stress / change.

Stephanodiscus coruscus sp. nov., a new species of diatom (Bacillariophyta) from June Lake, California (USA) with close affiliation to Stephanodiscus klamathensis

Modern and fossil populations of a Stephanodiscus Ehrenberg species from June Lake, California (USA) were analysed using light and scanning electron microscopy (SEM). Stephanodiscus valves were a major constituent of almost all analysed samples, often dominating fossil assemblages dating back several thousand years. The most commonly observed Stephanodiscus specimen in the samples bore a striking resemblance to the extinct Late Pliocene species Stephanodiscus klamathensis, particularly under light microscopy. The population size range, ultrastructure, and other defining characteristics closely matched published information on S. klamathensis. However, under SEM, internal views of the specimens from June Lake showed an important difference; specimens lacked valve face fultoportulae, whereas S. klamathensis is characterized by the presence of two valve face fultoportulae, each with three satellite pores near the centre of the valve. Additional differences in valve size range, absence of fultoportulae on the valve face, and the fact that S. klamathensis is an extinct species (observed in diatomites deposited from Late Pliocene to Pleistocene) with no closely related living relatives, necessitates describing this Stephanodiscus as a new species. To date, Stephanodiscus coruscus has been observed only in June Lake, California; most Stephanodiscus that share strong morphological similarities to this species have only been observed in ancient fossil diatomites. Thus, Stephanodiscus coruscus Jeff. R. Stone, Edlund & Streib sp. nov. is not only a new species but also provides a rare glimpse into the likely types of environments that S. klamathensis and other similar ancient Stephanodiscus may have inhabited in the late Pliocene. Character variations between S. coruscus and S. klamathensis reveal potential patterns of evolution in freshwater lineages, such as character loss, over time.

New and interesting diatoms from Tibet. II. Description of two new species of monoraphid diatoms

Light (LM) and scanning electron microscopy (SEM) observations were used to describe two new species of the freshwater monoraphid genus Crenotia Wojtal. Both species, Crenotia distincta, sp. nov. and Crenotia oblonga, sp. nov. have a unique stria structure, bi- to multiseriate terminating near the axial area. Internally, these terminal areolae have C-shaped openings that are occluded by a tapering flap, a feature unique to Crenotia species in China. The two species are easily distinguished from each other and from other members of the genus in both LM (size and valve outline) and SEM stria structure. The bi- to multiseriate nature of the striae suggests an affinity of this genus with Planothidium, but further phylogenetic analyses are required before the phylogenetic position of this genus is settled. Verified records of Crenotia are currently known from Europe and Asia, although species included in the genus by Wojtal have also been reported from North Africa and North America. The genus was originally described from springs but seems to have a wider ecological distribution.

A new freshwater Psammodictyon species in the Taihu Basin, Jiangsu Province, China

We describe a new species of diatom, Psammodictyon taihuensis sp. nov., collected from the Taihu Basin, Jiangsu Province, China. There are several features of this diatom that suggest it should be included in the genus Psammodictyon, notably the possession of panduriform valves characterized by a longitudinal fold near the apical axis, coarsely areolate striae, and a keeled raphe system present on the valve margin. This species is distinct from others in the genus by its small size, being only 16.5-25.0 μm long and 10.0-12.5 μm wide in the central region, and with the widest valve being 10.5-13.5 μm in width. There are 8-11 distinct fibulae per 10 μm and the striae are composed of 18-22 coarse areolae per 10 μm. This is the first report of a freshwater member of the genus Psammodictyon in China, which expands the known geographical and ecological distributions of the genus and enhances our understanding of freshwater diatom diversity in China.

Haslea nusantara (Bacillariophyceae), a new blue diatom from the Java Sea, Indonesia: morphology, biometry and molecular characterization

Background and aims – The present study aims to describe a new species of pennate blue diatom from the genus Haslea, H. nusantara sp. nov., collected from Semak Daun Island, the Seribu Archipelago, in Indonesian marine waters.
 Methods – Assessment for species identification was conducted using light microscopy, Scanning Electron Microscopy and molecular techniques. The morphological characteristics of H. nusantara have been described, illustrated and compared to other morphologically similar blue Haslea taxa, distributed worldwide. Additionally, molecular characterization was achieved by sequencing plastidial and mitochondrial genomes.
 Key results – This new species, named Haslea nusantara, cannot be discriminated by its morphology (stria density) but it is characterized by its gene sequences (rbcL chloroplast gene and cox1 mitochondrial gene). Moreover, it differentiates from other blue Haslea species by the presence of a thin central bar, which has been previously reported in non-blue species like H. pseudostrearia. The complete mitochondrion (36,288 basepairs, bp) and plastid (120,448 bp) genomes of H. nusantara were sequenced and the gene arrangements were compared with other diatom genomes. Phylogeny analyses established using rbcL indicated that H. nusantara is included in the blue Haslea cluster and close to a blue Haslea sp. found in Canary Islands (H. silbo sp. ined.).
 Conclusions – All investigations carried out in this study show that H. nusantara is a new blue-pigmented species, which belongs to the blue Haslea clade, with an exceptional geographic distribution in the Southern Hemisphere.

Cymbopleura laszlorum spec. nov. (Cymbellaceae, Bacillariophyceae), a glacial relic from a calcium-rich floodplain fen in southwestern Montana, USA

Cymbopleura laszlorum is described using LM and SEM microscopy from a recently rehabilitated floodplain fen in southwestern Montana, USA. The new species is most similar to C. mongolica and C. stauroneiformis and shares features with several other northern/alpine species. Cymbopleura laszlorum lives in cold, calcareous, spring-fed pools where it is associated with Mastogloia lacustris, Cymbopleura florentina and Epithemia argus. The fen also supports three rare vascular plants that have northern/alpine affinities. These diatom and vascular plant associates and the close morphological resemblance of C. laszlorum to C. mongolica and C. stauroneiformis suggest that the new species is a glacial relic and survives at the type locality because it has retained the muskeg-like conditions that were more widespread during the last glacial period. Wetland habitats that support rare species of vascular plants are also likely to support new and rare species of diatoms.

Halamphora oceanica (Catenulaceae, Bacillariophyta), a new species from the epipelagic region of the southwestern Gulf of Mexico

In the oceanic zones of the Gulf of Mexico a new species of diatom was found belonging to the genus Halamphora. Live cells were isolated using basic microbiological techniques for culturing and DNA analysis. Observations to determine morphological and morphometric characteristics were performed by both light and scanning electron microscopy. In addition, a phylogeny was built based on the expression and sequencing of the small subunit of the 18S gene. As a result of these observations, we conclude that this pennate diatom is a new species here proposed as Halamphora oceanica.

New Freshwater Gomphonemoid Diatoms from Streams in the Sierra Nevada Mountains, California, USA

Light and scanning electron microscopic observations of three new species of freshwater gomphonemoid diatoms are presented from mountain streams in California: Gomphonema californicum sp. nov., Gomphonema sierrianum sp. nov., and Gomphoneis oreophila sp. nov. Two of the species have morphological novelties related to the structure of the areolae, which are discussed in comparison with similar taxa. Gomphonema californicum shows a variety of areolar morphologies (i.e. lineola-like, c-shaped, and circular) within a single uniseriate stria. Unique to Gomphoneis oreophila, a member of the Herculeana subgroup, are the uniform areolae with circular openings without apparent occlusions. All of these species are distributed in remote streams of the Sierra Nevada Mountains of California, suggesting there are still new species to be found in this biodiversity-rich region.