Abstract: The diatom genus Tabellaria Ehrenberg is one of the most widely distributed genera in freshwaters, both in benthos and phytoplankton. It is rather frequent in unpolluted, circumneutral to slightly acidic and poorly mineralized lakes, streams and peat bogs. Despite being studied intensively in the last decades, the taxonomy of this genus is still unsatisfactory as some authors recently proposed to consider most species as synonyms of Tabellaria flocculosa (Roth) Kutzing. Several dozen of Tabellaria rich samples from Europe were investigated and six were selected to illustrate typical populations. Five new species are described based on detailed LM and SEM observations: Tabellaria acidodelicata sp. nov., Tabellaria hercynica sp. nov., Tabellaria koppeniana sp. nov., Tabellaria procera sp. nov. and Tabellaria valdeventricosa sp. nov. Additionally, the type materials of T. fenestrata, T. flocculosa and T. ventricosa have been investigated and illustrated together with a discussion on Tabellaria andina stat. nov., at present exclusively found in South America.

Abstract: Our environmental DNA analysis identified Annamia-like operational taxonomic units (OTUs) from Lake Kasumigaura, Japan every summer season during the period from June 2012-May 2015. A strain from Lake Kasumigaura that agreed with an Annamia-like OTU (NIES-4383) was established with a cell-sorting machine. Based on the differences in morphology and 16S rRNA sequences, a new taxon is described: Annamia dubia Tuji, Yamaguchi et Niiyama sp. nov. A. dubia produces a microcystins that is also produced by A. toxica. Our 16S rRNA phylogenetical analysis reveals that the genus Annamia makes a monophyletic clade with the genera Geminocystis, Geminobacterium, and 'Cyanobacterium.' Although this clade agrees with Cyanobacteriaceae Komarek et al. (2014), this family is invalid based on the invalid genus Cyanobacterium and the type species Cyanobacterium stanieri. We propose the alternative name Geminocystaceae Tuji, Yamaguchi et Niiyama fam. nov. based on the genus Geminocystis.

Abstract: The present study described two new Nostoc species, Nostoc favosum (CHAB5709, CHAB5713, and CHAB5714) and Nostoc mirabile (CHAB5756 and CHAB5784) based on the polyphasic approach combining morphological, genetic and ecological characteristics. Five investigated strains were found to possess morphological features of the Nostoc genus. Results showed that the 16S rRNA gene sequences of these five strains displayed ≥ 95%, and ≤ 98% similarity to the genus Nostoc. The 16S rRNA gene phylogenetic analysis inferred using bayesian inference, maximum-likelihood and neighbour-joining methods placed these five strains on two separate nodes away from other Nostoc species. The 16S-23S rRNA internal transcribed spacer (ITS) secondary structure of two new species showed a unique pattern of D1-D1', Box-B and V3 helix, which distinguished them from other Nostoc species. And the two species were further established by percent dissimilarity of ITS between another Nostoc species.

Abstract: Based on literature data, Fragilaria capucina seems to be a widespread species, often split into a large number of varieties. In the present study, the original type material was investigated, together with the type material of two varieties, originally described by Grunow as the var. acuta and the var. acuminata and the type material of Fragilaria sandellii and F. nevadensis. The results of all morphological analyses indicated that F. capucina is clearly different from the other species based on the number of rimoportulae, valve outline and spine morphology. The var. acuta and var. acuminata are conspecific with F. nevadensis and are added as synonyms of the latter. Additionally, three unidentified populations from Sweden and the United Kingdom that showed some resemblance to F. capucina were analysed. Using detailed LM and SEM observations, these three populations showed sufficient morphological differences from all other Fragilaria species and are therefore described as new for science: F. malouana Van de Vijver et Jarlman nov. sp., F. battarbeeana Van de Vijver, M.Kelly, C.E.Wetzel et Ector nov. sp. and F. ennerdalensis Van de Vijver, M.Kelly, C.E.Wetzel et Ector nov. sp.

Abstract: Florida is a diverse region that supports abundant cyanobacterial diversity, especially in terrestrial environments. To exploit this environment for cyanobacterial diversity, several greenhouses from central Florida were sampled to identify common nuisance and contaminating algae. Most of the algae observed were mat forming, covering nursery pots, plants, and equipment which were macro- and microscopically morphologically analogous to Brasilonema. Although macroscopic thallus morphology was similar among the samples, microscopic morphological characteristics such as size, color, and sheath formation were disparate. To uncover the cryptic diversity, mats were processed for species isolation, culture, and molecular taxonomic identification. A total of eleven Brasilonema strains were isolated into culture and systematically identified using 16S rRNA and 16S-23S rRNA ITS sequences. Based on morphology and molecular data, five species of Brasilonema were found and three are new to science: B. fioreae, B. santannae, and B. wernerae.

Abstract: Sampling of fungi in a grassland on a hill in Rojkov, Central Slovakia, revealed a new species of Luticola (Diadesmidaceae). Its terrestrial populations were found close to the basis of the fertile part of the geoglossoid fungi (Geoglossaceae) that were overgrown with filamentous cyanobacteria of the orders Oscillatoriales and Synechococcales. Luticola rojkoviensis sp. nov. is characterized by the valve outline and the structure of the external valve face: valves are weakly dorsiventrally asymmetrical, rhombic-lanceolate in larger cells to rhombic-elliptic and tri-undulate in smaller cells, with shortly protracted and broadly rounded valve apices. Valve face is minimally concave, as the axial area is lowered and the area around distal raphe elevated. The surface of the valve is mostly uneven due to many depressions, so the external shape of the areolae and the impression of irregular longitudinal rows depend on the extent of these valve ornamentations. Proximal raphe endings are unilaterally slightly deflected, expanded into small central pores. The shape of both the proximal and the distal raphe fissures is slightly asymmetrical. The morphological characteristics of Luticola rojkoviensis sp. nov. are remarkably similar to those of L. hustedtii Levkov, Metzeltin et A.Pavlov, L. ectorii Levkov, Metzeltin et A.Pavlov and L. acidoclinata Lange-Bertalot. The association of Luticola rojkoviensis sp. nov. with geoglossoid fungi and epiphytic cyanobacteria is discussed.

Abstract: Fifty-four streams of the Iberian Peninsula were investigated to document the species richness and phylogeny of Batrachospermum and morphologically similar genera, determine phylogenetic affinities of taxa and infer biogeographic trends. Species were identified using morphology and DNA sequence data for the rbcL gene as follows: Batrachospermum gelatinosum, B. pozoazulense, Paludicola keratophyta, Sheathia arcuata, S. boryana, S. confusa, Torularia atra, Virescentia helminthosa, V. vogesiaca, and Volatus carrionii. Batrachospermum gelatinosum and S. boryana were most frequent (sampled from 16 and 11 streams, respectively). Torularia atra and V. vogesiaca were each collected in a single stream, whereas the other five taxa were present in three to six streams. Virescentia vogesiaca is well known from other parts of Europe but had previously not been reported from the Iberian Peninsula. Biogeographic trends based on DNA sequence data show a flora with most species being well represented in parts of Europe, two taxa (B. gelatinosum and V. carrionii) that are shared between Europe and North America, one between Europe and South America (Paludicola keratophyta) and one cosmopolitan species (T. atra). Previous studies reported twelve taxa in the region using current taxonomy. This study has confirmed seven of these taxa with sequence data and morphology.

Abstract: During a survey on freshwater epilithic diatoms from subtropical lotic environments belonging to the Cascavel River microbasin, Parana State, Brazil, we observed populations of a new Nupela Vyverman et Compere species. Morphological and meristic analyses were performed using light and scanning electron microscopy, resulting in the description of Nupela semifasciata sp. nov. This species is characterized by elliptic-lanceolate valves containing subcapitate apices in larger individuals and broadly rostrate-rounded apices in smaller ones, while the length/width ratio gradually decreases as the individuals become smaller. The central area unilaterally reaches the margin and always interrupts the row of areolae on the valve mantle. The valve mantle is externally composed of a second row of areolae near the apices. We cross-checked information with similar Nupela taxa, highlighting the main features that separate them. Nupela semifasciata was found in streams with acidic-neutral pH, low conductivity and low to high nutrient concentrations.

Abstract: Light and scanning electron microscope observations are made on some members of the section Obtusae in the genus Nitzschia (Bacillariales, Bacillariophyceae). We use type and other material derived from both the National Water Quality Assessment (NAWQA) program in the USA and from Egypt to assess five different taxa, two of which are described as new to science (Nitzschia lowei, sp. nov., Nitzschia potapovae, sp. nov.) and another is made as a new nomenclatural combination (Nitzschia kurzeana var. multistriata (Hohn) comb. nov.). Other names used in the literature for some of these taxa are considered and discussed. Based on the features of sigmoid valves, eccentric raphe not in an elevated keel, lack of a conopeum, strongly bent, elongated external proximal raphe ends extending onto the valve face, and presence of a differentiated central 'nodule', members of this group are clearly differentiated from the generitype of Nitzschia and most other recognized sections of the genus.

Abstract: Three distinctive species of the diatom genus Iconella Jurilj were described from tropical areas of China. These new species all have the canal raphe extending around valve margins, keel raised off the valve surface forming wings, fenestrae obvious and alar canals that are uniformly porous. Together these features suggest these species should be assigned to the newly re-established genus Iconella. Here we describe Iconella shiwana Yan Liu, Ziyi Jiang et Kociolek sp. nov., Iconella pseudoconstricta Yan Liu, Ziyi Jiang et Kociolek sp. nov. and Iconella uniformis Yan Liu, Ziyi Jiang et Kociolek sp. nov., all described on the basis of light and scanning electron microscope observations from material collected from Hainan and Southern Guangxi Provinces. Iconella shiwana differs from other taxa by its isopolar valves and broadly round apices, tri- to quadriseriate short striae and large elliptical hyaline area in the valve center. I. pseudoconstricta is also isopolar, but it has acute ends and a constricted valve center. I. uniformis has heteropolar valves with a broadly rounded head pole and acute foot pole, a large spine is present near the head pole, and hook-like helictoglossae present at the foot pole. Our previous studies in tropical areas in China showed the diatom flora includes endemic taxa, although additional investigations are needed to explore and describe the abundant biodiversity there.

Abstract: Three new species of the genus Stauroneis Ehrenberg are discovered from the Northern Western Ghats of India - Stauroneis datarii sp. nov., Stauroneis bahlsii sp. nov., and Stauroneis hamiltonii sp. nov. Based on light microscopy (LM) and scanning electron microscopy (SEM) observations, detailed morphological features are presented and each taxon is discussed in comparison with similar species within the genus. Features of linear-lanceolate valves with median constriction, rounded apices, bow-tie shaped stauros, and radiating striae characterize Stauroneis datarii. Stauroneis bahlsii has large, lanceolate valves, with obtusely-rounded apices, a bow-tie shaped stauros that may have isolated areolae in some valves. Stauroneis hamiltonii possesses linear-lanceolate valves, broadly rostrate apices, characteristic bow-tie shaped stauros, and radiate striae. All of the taxa share a characteristic pseudoseptum at the apices. The recent discoveries of many novel taxa from the terrestrial and semi-aquatic environments of the Northern Western Ghats highlight the role of non-aquatic habitats in unmasking the diatom diversity of the Indian subcontinent.

Abstract: The taxonomy of coccoid cyanobacteria has been largely revised in recent years. In this study, a novel coccoid cyanobacterial strain was isolated from a watercourse at the Poyang Lake Model Research Base, Jiangxi province, Eastern China. A polyphasic approach combining morphological and molecular testing was used to characterize this strain referred to as CHAB 4018. Regarding colonial form and cellular spatial arrangement, this strain was morphologically similar to strains of the genus Eucapsis. The maximum 16S rRNA gene sequence similarity of this strain to the currently described cyanobacteria genera was 93.40%, exceeding the cutoff for genus delimitation in bacteriology. Furthermore, a phylogenetic tree based on 16S rRNA gene sequences indicated that strain CHAB 4018 formed a unique clade in the family Chroococcaceae and was phylogenetically close to the recently established genus Cryptococcum but distant from the Chroococcus 'sensu stricto' clade and from Eucapsis. Thus, a novel coccoid cyanobacterial genus with a new species is here described as Neochroococcus gongqingensis. A large phylogenetic tree using more strains suggested phylogenetic intermixture of Chroococcus-like and Eucapsis-like cyanobacteria, suggesting the need for further studies on the phylogeny and taxonomy of coccoid cyanobacteria.

Abstract: Biodiversity "hotspot" areas have been shown to possess unique diatom floras. During our diatom studies of some of these types of areas in China, samples were collected from Hainan and Guangdong Provinces, and four species from 4 different genera are proposed as new to science based on LM and SEM observations. These new taxa are Eunotia dinghunsis Liu & Kociolek, sp. nov., Brachysira subirawanae Kociolek & Liu, sp. nov., Microcostatus muscus Liu & Kociolek, sp. nov. and Iconella sanyatangum Liu & Kociolek, sp. nov. In addition, a species known previously only from Java and Sumatra, Pinnularia rivularis Hustedt, was observed, and herein we provide LM and the first SEM observations of this species.

Abstract: Examination of type material for Ulnaria splendens, Ulnaria aequalis and Ulnaria obtusa provides evidence to support each as a distinct and definable taxon. None can be considered more closely related to any other species in the genus Ulnaria and are therefore all recognised at the same rank, that of species. We briefly discuss five further taxa that involve the name Synedra splendens: Synedra splendens var. marina, Synedra splendens var. salina, Synedra splendens var. brevis, Synedra splendens var. subspathulata and Synedra (ulna var.) spathulifera.

Abstract: A new monoraphid diatom species appeared successively in paleolimnological records from a Quaternary sediment core (1.5±0.1 Ma) retrieved from Colonia basin (Brazilian Coastal Plain, Atlantic Forest, Sao Paulo Metropolitan Region), and is formally described as Planothidium scrobiculatum sp. nov. We studied the new species through light and scanning electron microscopy and discussed its similarity to other members of the genus. The new species has a unique combination of morphological features that allow its separation from all other species in the genus: (1) lanceolate valve outline with cuneate apices, (2) multiseriate striae composed of two to four rows of irregular sized areolae on the rapheless sternum valve (SV), not interrupted at the valve mantle junction, and (3) arrangement of areolae on the valve mantle, grouped in 3 or 4 rows, each composed of 2 to 3 areolae on the SV. Nevertheless, the new species main diagnostic feature is the occurrence of numerous, unusual, small shallow depressions externally located on the SV along the axial area, cavum, and virgae. As a result, P. scrobiculatum is different from similar species under LM and SEM by some evident characters or a combination of characters. This study contributes to the knowledge of the so far understudied biodiversity of microorganisms of tropical regions. In addition, the above-mentioned diversity patterns and the wealth of new diatom taxa inside and around the Colonia basin (many yet to be described) suggest that further samplings from other localities may provide an insight into its habitat preferences and range, since this area is an exceptional biological entity, worthy of further study.

Abstract: Many diatom groups are known for widespread (pseudo)cryptic species diversity and Pinnularia gibba group is one of them. Recently, Kollar et al. (2019) delimited species within the group by means of a polyphasic approach, providing an evidence for the existence of fifteen species. In order to further guide the systematic revision of the group, the present study focuses on the evolution and morphology of the P. gibba group. Using representatives of the fifteen species we used fossils to constrain and calibrate a multi-gene species-level phylogeny. Although many species are morphologically highly similar, significant differences in cell size were detected in different sections of the tree, suggestive of ongoing morphological differentiation. We further used the phylogenetic analysis to assess marker resolution for DNA barcoding, showing that the proposed diatom barcode markers rbcL and V4 SSU rDNA can distinguish closely related (pseudo)cryptic species of the group.

Abstract: Cyanobacteria are photo-oxygenic prokaryotes present in nearly all ecosystems, where they are important in global oxygen, carbon, and nitrogen cycles. They are often recognized as the harbingers of eutrophication in freshwater systems and are increasingly being noted as nuisance species in marine ecosystems such as coral reefs. In recent years, cyanobacteria have been intensely studied due to their toxicity, harmful bloom formation, and because their distribution and abundance are expected to increase with climate change. Nevertheless, for all of their importance, many gaps in our knowledge of cyanobacteria remain: the distribution, dispersal, and biogeography of these microorganisms are still not understood. Until 1994 little attention was paid to tropical cyanobacteria and their diversity, despite some harmful invasive species having their putative origins in tropical habitats. However, more practiced articulation and research has recently uncovered previously undescribed biodiversity, and in turn changed our knowledge of the evolutionary relationships within the Cyanobacteria. The purpose of this paper is to describe the challenges of working with the cyanobacteria and to review what we know of them from tropical habitats.

Abstract: We describe a new genus of monoraphid diatom based on Achnanthidium ovatum T.Watanabe et Tuji in Watanabe et al., a species described originally from Japan. We encountered this species from Yunnan Province in the southwestern part to eastern China, as well as in Luding, Sichuan Province and Xianju, Zhejiang Province, in pristine lotic environments. The species differs from the genus Achnanthidium by being asymmetrical to the transapical axis and has a pseudoseptum at the poles of the interior of the raphe valve which is fused with each helictoglossa. Moreover, a distinct group of condensed striae can be found at the narrower pole ('footpole') of the raphe valve. This appears to be the only known genus of freshwater monoraphid diatoms that is restricted to a single continent.

Abstract: This paper describes a new species from the Class Chlorophyceae, Mychonastes frigidus sp. nov., isolated from a cold-water mountain stream in the north of Russia (Subpolar Ural). The taxon is described using morphological and molecular methods. Mychonastes frigidus sp. nov. belongs to the group of species of the genus Mychonastes with spherical single cells. Comparison of ITS2 rDNA sequences and its secondary structures combined with the compensatory base changes approach confirms the separation between Mychonastes frigidus sp. nov and other species of the genus. Mychonastes frigidus sp. nov. represents a cryptic species that can only be reliably identified using molecular data.