During a survey of the diatoms present in aerophilic microhabitats associated with waterfalls in Misiones Province (Argentina), mainly within Iguazú National Park (N.P.), seventeen taxa belonging to the genus Humidophila have been recorded. Previously, only six species of the genus have been reported for all of Argentina. Of the seventeen taxa considered here, four exhibit a unique combination of features and are proposed as new species. These are H. iguazuensis sp. nov., H. lagartiensis sp. nov., H. misionera sp. nov. and H. sebastianii sp. nov. An additional six previously-described species (H. arcuatoides, H. contenta, H. nienta, H. parallela, H. platensis and H. subtropica) are reported. Of these previously-described taxa, only H. contenta has been reported previously from Argentina, so the occurrences of the others in the region expand their known geographic distributions. One taxon has been tentatively identified (as Humidophila aff. biscutella) and the remaining six taxa observed are presumed to be new but remain unidentified at the species level because they occurred in small numbers and could not be sufficiently documented for formal description. This is currently the largest concentration of Humidophila taxa reported in a relatively small geographic region anywhere in the world. Morphological features among the species of the genus are discussed, and we describe the structure of the features associated with longitudinal tubes in the genus. We also present and describe the ecological and biogeographic distributions of Humidophila species.

The centric diatom genus Discostella is common in freshwater communities worldwide. Sixteen extant species are currently known, many of which are morphologically very similar. In applied taxonomy mostly broader concepts of D. stelligera and D. pseudostelligera are used. To assess the species diversity of the genus, 58 strains were cultivated and investigated using morphometric and molecular methods, obtaining the first multi-gene phylogeny of Discostella. Up to 22 operational taxonomic units were identified. For the taxonomic assignment of the OTUs a detailed morphological analysis including several type materials was performed. Up to 15 OTUs did not fit any existing taxon, revealing previously undetected diversity in the genus. A comparison of the different molecular markers revealed hints of a more complex intrageneric structure possibly due to reticulate evolutionary processes. The identity and generic placement of D. glomerata is resolved and D. angainor sp. nov. is described.

The historic type material of Microneis gracillima, Navicula pyrenaica, Achnanthes amphicephala, Achnanthes thienemannii and Achnanthidium rostropyrenaicum was investigated together with additional European populations of these species using light and scanning electron microscopy. The morphology of the species was compared to similar taxa. Achnanthes amphicephala is transferred to the genus Achnanthidium. The species are distinguished from each other in the shape of their poles and in valve outline. There are currently very few photographic records of the species, but our results suggest that these species are typical in base-rich, oligotrophic waters, and might be important indicator species for these habitats.

: Two green algal specimens, newly recorded from China, were identified as Gongrosira burmanica Skuja based on their distinctive morphology. The thallus of these specimens appeared hemispherical, forming cushion-like masses with calcification, and featured erect filaments that were pseudodichotomously branched and partially merged with each other, radiating from the base. Ultrastructural investigation, particularly the observation of pyrenoids penetrated by thylakoid membranes and the absence of plasmodesmata in adjacent cells, provided confirmation that Gongrosira burmanica Skuja should be excluded from the order Chaetophorales. Phylogenetic evidence, based on nucleus (18S rDNA) and chloroplast (tufA, rbcL) sequences, clearly indicated that Gongrosira burmanica Skuja should be reclassified within the Ulvales (Ulvophyceae) as a new combination species of the genus Ulvella P. Crouan et H. Crouan, rather than the Chaetophorales (Chlorophyceae). Further evaluation of the genus Gongrosira Kützing is necessary, especially by examining additional specimens, including the type species. It should be noted that the diversity of the Ulvales has been underestimated.

In a Brazilian karst environment, composed predominantly of carbonate rocks, diatoms were collected in periphytic habitat (epiphyton, epilithon, epipsammon) in lentic and lotic water bodies from the Serra da Bodoquena. This Pantanal region is known for its tourist and scenic value, covering springs and rivers with extensive formation of active limestone tufa. Six species of Dorofeyukea were investigated under light and electron microscopy. The genus is characterized by a narrow stauroid fascia surrounded by some irregularly shortened striae, uniseriate slightly radiated striae, areolae circular or rectangular covered internally by a hymenes and apical pseudosepta. Four new species are described and compared with similar taxa Dorofeyukea bahlsii sp. nov., D. bodoquenensis sp. nov., D. calcarea sp. nov., and D. pantanalensis sp. nov. The new species are distinguished from each other and from similar taxa of Dorofeyukea mainly by the valve contour and shape of the apices. Dorofeyukea kotschyi (Grunow) Kulikovskiy, Kociolek, Tusset et T. Ludwig and D. texana (Patrick) Kulikovskiy et Kociolek were also recorded, described and illustrated in this study.

A coccoid cyanobacterial strain FACHB-3576 was isolated from Lake Hamatai, an alkaline-saline lake located near the Ordos Spirulina Industrial Park, Ordos, Inner Mongolia, China. This strain exhibited morphological similarities to the genus Cyanobacterium. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain FACHB-3576 formed a unique clade, distinctly separate from the other genera within the family Geminocystaceae. The genetic identity of 16S rRNA sequence between our strain and all other currently described genera in Geminocystaceae, including Cyanobacterium, was less than 95%. Moreover, this strain was further differentiated by its morphology and ecological characteristics. The strain is herein classified as a new cyanobacterial taxon Limnothece alkaliphila gen. et sp. nov. based on a polyphasic approach including data on morphology, ultrastructure, ecology, 16S rRNA phylogeny and secondary structure of the 16S-23S ITS region. The description of this novel taxon contributes to a better understanding of the diversity of coccoid cyanobacteria in alkaline-saline habitats.

The diatom genus Chamaepinnularia was first published by Lange-Bertalot et Krammer in 1996 to accommodate several small species previously included within Navicula and Pinnularia. Despite its morphological similarity to those two genera, the family-level classification of Chamaepinnularia has been considered incertae sedis since its description almost three decades ago. We provide the first molecular characterisation (18S and rbcL) of the genus based on cultured polar strains and investigated its phylogenetic placement. Molecular data are complemented with observations on living cells, as well as detailed examination of oxidized material with light microscopy and scanning electron microscopy. The 12 investigated strains were morphologically identified as three taxa: two already described species (C. gerlachei, C. krookii) and one here newly described (C. australis sp. nov.). These species formed three separate, well-supported branches in the phylogeny. Our analyses placed Chamaepinnularia as a sister group to members of the Sellaphoraceae for which sequence data exist (i.e. Sellaphora, Fallacia, Rossia and Diprora). Based on the presence of hymenate areolae, a single H-shaped plastid with girdle appressed plates and the results of the phylogenetic trees, we propose the inclusion of Chamaepinnularia within the family Sellaphoraceae, which altogether form a supported monophyletic group.

Environmental factors and diatoms were studied in 151 stations in Cypriot streams. Since Navicula simplex Krasske [new combination: Craticula simplex (Krasske) Levkov] is based on the small-scale drawing of a single valve and the type material is no longer available, we provide additional ecological, morphological, and ultrastructural data, and an epitype for C. simplex, which is distinguished by valve outline and stria density, and occurs in small, nutrient-enriched streams. Two other symmetric biraphid species are proposed as new to science based on light and scanning electron microscopy, careful comparison with similar established taxa, and on the analysis of our multi-annual databases. Mastogloia cyprica Lange-Bert. et Cantonati sp. nov. differs from similar species by raphe undulation, stria density, and rare occurrence in oligo- to slightly-eutrophic streamlets and lakes with medium-high conductivity. Navicula loumatensis Lange-Bert. et Cantonati sp. nov. is characterized by the combination of valve outline, central area, and by a high areola density, and occurs in medium-high conductivity, low-N but P-enriched streams. In-depth knowledge of Mediterranean stream diatoms is of pivotal importance in these critical decades of climate change.

Based on a review of material previously studied, and new water samples, species of the genus Amphorotia were investigated with respect to their morphology and geographical distribution, especially in subtropical Asian coastal areas. Six Amphorotia species from China are investigated. They all possess amphoroid frustule symmetry, presence of spines and, when detected, a single plastid. These features as well as other details of the frustules were documented with light and scanning electron microscopy. Five of the taxa, A. reimerii, A. mokonensis, A. baicalensis, A. zhujiangensis, and A. curvata are newly recorded as fossil specimens in the Jianghan Plain. Further comments on the taxonomy and morphological variation of several known species are given. One taxon, A. liangyanlingii sp. nov. was discovered from freshwater samples in the Pearl River. This new species is most similar to A. zhujiangensis Wu, Williams et Flower when observed in LM, but can be distinguished by ultrastructural details when viewed with the scanning electron microscope (SEM). Taxonomical studies of species in the genus Amphorotia are considered together with their biogeography and ecology.

Mallomonas Perty is a genus of photosynthetic and heterokont algae belonging to the order Synurales, within the class Chrysophyceae. It is the most speciose genus within the Synurales, and consists of motile unicells with a cell covering composed of highly sculptured and precisely arranged siliceous scales and bristles. The genus is a common and often important element of planktic habitats with species found in numerous types of aquatic environments. Mallomonas is divided into 19 sections, many of which are further divided into multiple series. The section Torquatae is one of the larger sections of the genus comprised of species with a distinctive arrangement of siliceous components and a unique forward projecting apical end, the collar. With the exception of a few localities, very little is known about the evolutionary history of the Synurales, including Mallomonas. In this study, we describe two new species belonging to section Torquatae from the early Eocene, which represent the first taxa for this section known from the fossil record. Because the general characteristics of all siliceous components are similar to those on modern species, it is clear that this section of the Mallomonas lineage was well-evolved by the Eocene.

We established a new cryptomonad species, Rhodomonas storeatuloformis sp. nov., based on morphological and molecular characters of cultured strain isolated from the Black Sea. Cells are slightly dorsoventrally flattened, obloid in shape, 12-19 µm in length and 5-10 µm in width, with light-brown, parietal H-shaped chloroplast and a central pyrenoid. Two unequal flagella are located subapically in a short V-shaped vestibulum with a ligule on the left side. Cells are covered by a sheet-like papillate perisplast with numerous small underlain ejectosomes; discharged ejectosomes form distinctly visible minute pores. Mid-ventral band is absent. In general, cell morphology is very similar to described strains of Storeatula genus. However, phylogenetic analyses based on sequences of the partial nuclear 18S, 28S rDNA, and complete internal transcribed spacer (ITS) region of rDNA placed the novel cryptomonad strain within Rhodomonas genus as a separate clade. The predicted secondary structure of nuclear rDNA ITS2 has numerous compensatory base changes compared to the closest relative strains that support the distinction of the novel species among Rhodomonas taxa. The present results contribute to the study on still hidden cryptomonad biodiversity in the Black Sea. Contradiction between morphology and phylogenetic data in R. storeatuloformis further argues for revision of the generic delineations in the family Pyrenomonadaceae.

The genus Microcrocis belongs to long ago established cyanobacterial taxa for which relevant data required for a modern taxonomic analysis remained unknown for a long time. In present study we proposed an epitype originating from a large natural population of the type species M. geminata. Through isolating clean individual colonies from the environmental sample, sufficient material for a single colony PCR and amplification of genomic DNA by MDA method was obtained. Molecular analyses of the 16S rRNA gene determined the unsuspected position of the cyanobacterium within the family Geminocystaceae, forming a distinct branch with two Merismopedia sequences. 16S rRNA and ITS analysis clearly separated the two taxa on generic level. The phylogenetic classification is conspicuously consistent with the ultrastructure of parallel thylakoids unique for some members of the family Geminocystaceae. Distinctive morphology of the genus including typical longitudinal division is discussed.

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.

Delicatophycus wulingensis sp. nov., D. qinghainensis sp. nov., and D. menyuanensis sp. nov., are described, illustrated, and compared to similar taxa. Two types of apical pore fields (APFs) in the genus Cymbella are defined. The three new Delicatophycus all possess the type II APF found in some species of Cymbella, i.e. the APF is divided by the distal raphe fissure into two areas, one larger than the other. They also share a further three distinct features: variable central dorsal portion of valve, stigmata, and a notch on the dorsal side of the distal raphe fissure. Since there are many species of Delicatophycus without APFs, such as D. sinensis M.J. Wynne, D. williamsii M.J. Wynne and D. chongqingensis M.J. Wynne; D. williamsii and D. liuweii Li both possess stigmata, thus proposed diagnostic characters for Delicatophycus are the tilde-shaped areolae and the dorsally curved distal fissures.

Navicula similecataracta-rheni and N. aquitanonipponica are two new Navicula species recorded from the Nouvelle Aquitaine Region, southwestern France. Both new species belong to the linear-lanceolate Navicula species complex. A detailed iconography based on light and scanning microscopy observations is given for the type and complementary populations. Comparisons with close related species based both on literature and on microscope observations, particularly with N. cryptotenella, N. cataracta-rheni and Navicula sancti-naumii, support the erection of the two new species.

Free-living protists play important roles in biogeochemical cycling and food-web chains in both aquatic and terrestrial environments. However, their biogeography and spatial distribution remain poorly resolved. Here, we used silica-scaled chrysophytes to determine the most important climatic, historical, and environmental variables that explain biodiversity patterns across different geographical scales; the continental scale was represented by 473 European sites (gradient of 3,800 km), the local scale comprised 69 Aquitanien (France) sites (gradient of 186 km). Generalized Additive Models were used to evaluate the relationship between species richness and explanatory variables. Partition of community variance into fractions, explained separately by local environment, history, and climate helped us to track the main drives of community composition. While species richness was evenly influenced by all factors at the European scale and predominantly by environment (pH) at the local scale, the main factor shaping community composition was climate at both scales and history (geographical distance) at the European scale. Our results showed that silica-scaled chrysophytes respond strongly to climate-related variables at a broad geographical scale. Our work highlights the effect of climate on protist biogeographic structuring and suggests that climate-related variables may represent one of the main drivers of protist distribution, similarly as in macroorganisms.

In this study, three new species of the genus Gomphonema from freshwater lakes of the lower reaches of Yangtze River, China. They include G. qii sp. nov. from Yangcheng Lake, G. poyangense sp. nov. from Poyang Lake, and G. longganense sp. nov. from Longgan Lake, and all of these new species were collected on stone. We detailed morphological features of these new species are described based on light microscopy (LM) and scanning electron microscopy (SEM), and the LM and SEM photographs illustrate the size ranges and particular ultrastructure of these new species. G. qii sp. nov. with clavate-lanceolate valves, bluntly rounded headpole and narrowly-rounded footpole, narrowly axial area, uniseriate striae. G. poyangense sp. nov. with clavate-lanceolate valves, rounded headpole and narrowly-rounded footpole, broadly rhombic-lanceolate axial area, short uniseriate striae, c-shaped to irregularly shaped areolae. G. longganense sp. nov. with slightly heteropolar, linear-lanceolate valves, protruded headpole and rounded footpole, narrowly axial area, variously-shaped areolae. Additionally, three new species only have one stigma per valve. We compare these new species with other similar species of Gomphonema based on valve outline, shape of the axial and center areas, and striae density. While their valve features and symmetry easily assign them to Gomphonema, their differences with 'core' species of the genus are discussed.

Surfaces of microscopic organisms are often adorned with various patterns whose putative functions are largely unexplored. In this study, we tested the hypothesis that the formation of parallel-arranged ribs improves the mechanical resistance of microscopic silica scales. Computer models of scales were constructed for chrysophyte species Mallomonas striata and Synura petersenii, varying the ribs number and orientation. The finite element method was used to evaluate the model static parameters. Our results showed a large difference in the function of ribs depending on the species studied. In S. petersenii, the ribs play a key role in scale stability by fixing the longitudinal tubular structure (the median keel) to the basal plate. Although a larger number of ribs increases the scale strength, in extant species the number of ribs is usually optimised to save silicate. In M. striata, on the other hand, ribs have a negligible effect on overall scale stability. Moreover, vertically arranged ribs that most stabilize the scales are very rarely produced in nature. This suggests that these ribs have a function other than improving the mechanical resistance of the scales.

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.

A new aerophilic diatom species, Humidophila manipurensis sp. nov., is described from the Sadu Chiru waterfalls, Manipur, India, a part of the Indo-Burma hotspot region. This species is characterized by having its valve shape slightly inflated at middle, terminal raphe ends that are slightly deflected, round areolae and a central depression. Further, we also recorded Humidophila bigibba from Meghalaya State, Northeast India, and this population is compared with the type population from Indonesia and Chinese populations. Fine structural details of both taxa were examined using light and scanning electron microscopy and compared with morphologically similar taxa in this genus. Addition of new species from this region will further add to the biodiversity richness of the Indo-Burma biodiversity hotspot. Further, this study confirms the presence of H. bigibba for the first time in India. This species has a deep constriction in the middle of the valve which is not found in the populations from the Indonesia and China.

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.

We add four new species to the recently established genus Lacustriella Kulikovskiy, Lange-Bertalot et Metzeltin and characterize morphology of the taxa based on LM and SEM observations. Lacustriella cuspidata, L. rombea, L. radiata and L. solita share all of the typical morphological features of the genus including longitudinal canal along each valve margin, radiate uniseriate striae terminated with large elongated areolae, and external distant raphe ends bent oppositely. L. cuspidata is peculiar among the other Lacustriella with rows of small pores look as if they continue striae on the surface of longitudinal canals as well as with the axial area sharply widened into the asymmetrical central area. L. rombea is different in combination of valve outline with unprotracted rostrate apices, irregular areolation at centre of the external valve, and slit-like areola occluded with volae. In L. radiata distinctive characters include protracted rostrate valve apices, rhombic central area and volated slit-like areolae. L. solita differs in the highest density of areolae in striae and an ornamented surface of longitudinal canals. New species were compared to the closest morphologically similar taxa. Some general ecological properties and distribution in the littoral zone of the ancient lake are given.

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.

A new species, Luticola jinshaensis sp. nov. is described from Xiangjiaba reservoir in Jinsha River, China. Observations on the new species were based on light microscopy (LM) and scanning electron microscopy (SEM). Luticola jinshaensis sp. nov. is distinguished from all other species of the genus in having an unusual external areolae structure, where each areola has a cribrum recessed and ornamented with tiny, irregular projections connected with inner wall of areolae raphe. This cribrum is fragile so that the structure may become destroyed by processing of the specimens. A second feature that distinguishes this new taxon is that the deflection of the distal raphe fissures which, in most case, are first deflected towards the same side as the proximal endings and then towards the opposite side and continuing onto the mantle. Occasionally, the external distal raphe fissures are first hooked towards the same side of the proximal endings, then towards the opposite side and, finally, then bent to the same side as the proximal endings. The new species is epilithic and lives in freshwater habitats, notes on its ecology and distribution are added.

A new species, Chara lipkinii, was described based on specimens from the Mediterranean, Israel. Dioecy, 10-13 branchlets in a whorl, complete tylacanthous to isostichous displostichous axial cortex with very short solitary spine cells, hardly visible diplostephanous bistipulate short obtuse stipulodes, frequently appearing as haplostephanous, in combination with completely ecorticate branchlets without cortex initials and with 1-3, mainly two nodes with unilateral bract cells distinguish it from species of Chara described to date. Its morphological traits, which are most important in the infrageneric taxonomy described by Wood, point towards its placement in the subsection Chara, rather than its distant clustering with both Chara and Grovesia. The oospore surface of C. lipkinii showed no features allowing identification based on oospore morphology only, but could be useful to distinguish it from some species. According to our analyses, the genetic affinity of species based on rbcL and ITS1 mostly does not support infrageneric division of the genus Chara based on morphological traits. Chara lipkinii is a freshwater and brackish water species, growing in small shallow inland water bodies and streams in the Eastern Mediterranean, i.e., in one of the most threatened water bodies of the region. The species faces a very high risk of extinction in the wild. It has disappeared from all previously discovered localities, which no longer support charophyte populations. The gradual decline and disappearance of living plants from one recently discovered locality of C. lipkinii were observed as a result of heavy sediment accumulation and eutrophication. Urgent action to restore the habitat needs to be taken.

A new freshwater diatom species Conticribra sinica sp. nov. Yu, You et Wang from three lakes in the lower reaches of the Yangtze River, China, is described here using a combination of morphological and molecular data from ribosomal DNA genes. The primary distinguishing characteristic of C. sinica was the presence of a non-plicate or slightly-plicate valve face and a single ring marginal fultoportulae that was located at the junction between the valve face and the mantle. There were 4-11 valve face fultoportulae that were located at the subcenter of the valve face. In addition, a single rimoportula replaced a marginal fultoportulae. Areolae loculate were open to the outside by irregularly circular foramina or slit foramina that are radially arranged. Internally, cribra were continuously arranged long a radial arrangement of areolae. Characteristics of the new species with other similar species of Conticribra. Phylogenetic analysis of the nuclear small subunit (SSU) rDNA sequences and nuclear large subunit (LSU) rDNA gene sequences revealed that C. sinica in a single clade at a considerable sequence distance from the other Conticribra species.

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.

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.

The composition of the diatom assemblages was analysed in four rivers of Upper Silesia, Poland in 2017. The diatom assemblages studied were found to reflect anthropogenic salinization caused by mining activities. The assemblages in those rivers characterised by the highest salinity (Bolina and Mleczna) showed a relatively low taxonomic richness. The diatom assemblages were dominated by species typical of brackish or marine waters. The rivers with a minimal or weak anthropogenic impact (Centuria and Mitręga) supported taxonomically richer diatom assemblages typical of mid-altitude siliceous or calcareous streams (respectively), that have a fine particulate substratum. The presence of a new species, Planothidium nanum sp. nov., was revealed. The new species shows a unique set of morphological characters, including small size; its elliptical outline as well as very widely-spaced central striae on the sternum valve (sinus) and widely-spaced central striae on the raphe valve allow to separate it from other similar Planothidium.

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.