Raphe Endings Research Articles

Prestauroneis dayaensis—a new diatom species (Bacillariophyceae: Stauroneidaceae) from Guangdong Province, China

In this study, we describe a new diatom, Prestauroneis dayaensis sp. nov., found in a coastal river, Danao River, at Daya Bay, Huizhou City, Guangdong Province, China. A detailed morphological description of the new species is provided based on light and scanning electron microscopy. P. dayaensis sp. nov, has an elliptical to lanceolate-elliptical valve outline with distinctive rostrate to subcapitate apices, the raphe straight, and the proximal raphe ends slightly enlarged toward to the same side. Its areolar structure is variable in shape, circular at the central area, linear to elliptic at the ends, and distinct pseudosepta present at both apices. Length 25.5–32.0 μm, width 8.0–11.5 μm. This axial area is narrow and linear. The central area is nearly rectangular, some with one short stria at one side of the valve. Striae are relatively widely spaced and radiate at the center, becoming nearly parallel at both apices. The new species is compared with species from the genus Prestauroneis and Dorofeyukea.

Two new diatom species of the genus Gomphonemopsis (Bacillariophyceae) from the coast of China and two new combinations for the genus.

Two new diatom species belonging to the genus Gomphonemopsis are described, Gomphonemopsisnanasp. nov. and Gomphonemopsisgaoisp. nov. These two species were compared in detail with congeners. Gomphonemopsisnana is distinguished by its high stria density and small size. This species was found so far to be epiphytic only on the eelgrass collected from Qingdao Bay (Yellow Sea). Gomphonemopsisgaoi is characterized by its isopolar valves, simple proximal raphe endings and acutely rounded apices. This taxon was separated from the exoskeleton of marine copepods sampled from the Futian Mangrove Nature Reserve (South China Sea). In addition, two new combinations, Gomphonemopsisoahuensis (Hustedt) Lang Li, Yuhang Li & Changping Chen, comb. nov. and Gomphonemopsisplatypus (Østrup) Lang Li, Yuhang Li & Junxiang Lai, comb. nov. are proposed. This study increases the records and knowledge of Gomphonemopsis along the coast of China.

Achnanthidium guarulhense sp. nov. (Achnanthidiaceae, Bacillariophyta), a new diatom species from a Conservation Unit in Southeast Brazil

This study describes the new species Achnanthidium guarulhense sp. nov. from the oligo-mesotrophic Negro Lake located in a Conservation Unit in Southeast Brazil. Its morphology was analyzed through Light (LM) and Scanning Electron Microscopy (SEM). The most striking feature of the new species is its narrow linear-lanceolate axial area expanding to a linear-elliptic central area between the proximal raphe ends. This feature makes the proximal raphe ends appear more distant from each other than in other species of the genus. We also provide its ecological information and a comparison with closely related species. Our results contribute to the knowledge of the biodiversity of tropical diatoms and provide subsidies for monitoring studies.

Description of five new Luticola D.G.Mann (Bacillariophyta, Diadesmidaceae) species from Indonesia with comments on the morphological boundaries of the genus.

During a survey of the Indonesian diatoms, five Luticola D.G.Mann taxa that could not be identified, based on the available literature were discovered. Based on light microscopy, scanning electron microscope observations and comparisons with similar taxa, all of them are described as new species. All taxa were found on mosses growing on tree trunks and concrete on the islands of Banda Besar and Seram and from spring on Java Island. Luticolainsularissp. nov. is most similar to L.aequatorialis and L.simplex, but it can easily be distinguished from both taxa, based on the lower striae density, the narrower valves and the well-developed silica ridges on the valve face/mantle junction. Luticolabandanensissp. nov. resembles L.frequentissima, but they can be easily distinguished, based on their valve widths and the direction of the grooves located on the distal and proximal raphe endings. Luticolaellipticasp. nov. is most similar to L.sparsipunctata, L.tenuis and L.bryophila. Amongst all the species compared, L.ellipticasp. nov. is the only one with a highly asymmetrical central area, with the isolated pore located on the wider side. Luticolamalukuanasp. nov. shares similarities with L.dismutica and L.areolata, but it has a notably higher stria density. From L.areolata, it can also be separated by the morphology of striae and the lack of ghost areolae in the central area. Luticolapoliporeasp. nov. is unique in the whole genus due to the presence of multiple isolated pores.

New genera and new species of Catenulaceae (Bacillariophyta) from Coral Reef habitat of two Indonesia islands-Bawean and Sulawesi-A morphological approach.

Indonesia is listed as a region with high marine biodiversity, especially when considering the three large tropical ecosystems: seagrass beds, mangroves and coral reefs. It is likely that the biodiversity of diatoms in this area is also high. Samples for this research were taken from the remote area of Bawean Island and Tomini Gulf in Central Sulawesi. In this research, we explored marine benthic diatoms from coral reef areas and presented two new genera: Paracatenula and Wallaceago, and seven new species: Paracatenulaporostriata sp. nov., Wallaceagoporostriatus sp. nov., Catenulaboyanensis sp. nov., C.komodensis sp. nov., C.decusa sp. nov., C.densestriata sp. nov., and Catenulopsisbaweana sp. nov. The new genus Paracatenula is characterized by its perforated cingulum, and the genus Wallaceago is distinguished by its proximal and apical raphe ends bent to the ventral side and the presence of a stauros in the mantle.

Molecular Investigation of the Achnanthidium minutissimum Complex (Bacillariophyceae) from the Transbaikal Region with the Description of Three New Species

Representatives of the Achnanthidium minutissimum complex have been studied from the Transbaikal region, Russia. The Transbaikal region is known for its unique algal flora and high levels of endemism. Despite the group of monoraphid diatoms being studied quite extensively in this region in recent years, only four species of Achnanthidium have been reported so far. Three new species are described based on LM and SEM microphotographs and molecular data: Achnanthidium baicalonanum sp. nov., A. obscurum sp. nov. and A. angustum sp. nov. Comparison with similar species is given. The new species differ from other species of the genus by valve shape, striae and areolae structure, shape of external distal raphe ends and central area. According to molecular data, the new species form separate branches within the A. minutissimum complex. Ecological preferences of the new species are examined. All of the new species are only known from the Transbaikal region. This study contributes to the understanding of Achnanthidium taxonomy and biogeography and will be an asset to future biomonitoring studies.

Luticola tenera sp. nov. (Diadesmidaceae, Naviculales)-A New Diatom from the Soil of the State Nature Reserve "Bastak" (Jewish Autonomous Region, Russia).

Diatoms inhabit different aquatic and non-aquatic environments, including soils. The naviculoid genus Luticola is widespread in various habitats and accounts for 264 species that are only based on morphological and morphometric characteristics. These parameters can greatly vary during the life cycle, making the species very similar to each other and complicating their unambiguous identification. During a study on soil algal diversity in the Russian Far East (Jewish Autonomous Region), we isolated a strain of naviculoid diatom and examined it using an integrative approach (phylogenetic, morphological, ultrastructural data, and life cycle). Phylogenetic analyses, based on chloroplast rbcL gene data, showed affinity of the new strain with the genus Luticola. Our alga shares morphological features typical of the genus members but differs from them by having valves with a larger width and hook-shaped external proximal raphe ends deflected to the side opposite the stigma. It was revealed that the strain reproduces via two types of sexual reproduction-isogamy and cis-anisogamy. Based on these phenotypic traits, we described the new isolate as Luticola tenera sp. nov.

Taxonomy of three new Neidium Pfitzer species of the Arapiuns and Tapajós Rivers Basin (Santarém, Pará, Brazil)

During our investigations on the taxonomy of diatoms of clear water habitats in the western Pará region, we found three interesting, previously undocumented Neidium species. This study was based on samples taken from different habitats (plankton and sediment) in the Arapiuns and Tapajós Rivers, as well as three lakes. Based on light and scanning electron microscope observations, three new Neidium are distinguished from one another and their congeners by differences in valve outline, stria density, striation pattern, number and position of longitudinal canals and external proximal raphe endings. Furthermore, we provide formal descriptions of these new species and compare them with others similar species. We also discuss variation in several features of taxa currently assigned to the genus Neidium.

Placoneis modaomensis sp. nov. (Bacillariophyta; Cymbellaceae), a new species from Guangdong Province, China

One new species, Placoneis modaomensis, found in freshwater environment from tributary of the Pearl River which lies in Modaomen Channel, Zhuhai County, Guangdong Province, China, is described based on light and scanning electron microscope observations. P. modaomensis sp. nov. has the morphological features that are typical for the genus, including external terminal raphe fissures curve to the opposite sides and areolae with internal volate occlusions. The new species is similar to P. amphibola (Cleve) E.J. Cox, P. amphiboliformis (Metzeltin, Lange-Bertalot & Soninkhishig) Vishnyakov, P. parvapolonica Lange-Bertalot & Wojtal, P. clementispronina Lange-Bertalot & Wojtal and P. nanoclementis Lange-Bertalot & Wojtal in the shape of the valves and having course striae but it can be easily distinguished by the two main morphological characteristics: external central raphe endings bent in the opposite directions, and areolae covered by volate occlusions externally. The latter feature appears to be new for taxa assigned to the genus Placoneis. Data on the associated diatom flora and its ecology are also given. These findings increase our understanding about the morphology of Placoneis in general and its and distribution of the genus in China.

Adlafia kociolekii sp. nov. (Bacillariophyceae): a new naviculoid diatom from the Eastern Himalayas, India

We describe Adlafia kociolekii sp. nov. from aerial habitats in Sikkim, India, a part of the Eastern Himalayas. The species is described based on light and scanning electron microscopic observations. The main diagnostic features include valves are clear elliptical, a narrow axial area at the centre, radiate to convergent striation, and distinctive Voigt discontinuity at both apices. In terms of ultrastructure, the features that identify this species as new are the internally presence of raphe on the elevated sternum, with distal raphe ends distinctly deflected to opposite sides of proximal ends, and distal ends terminating in long and thickened helictoglossae. The species was also recorded from wet walls and freshwater habitats of north-east India, in the present study. The morphological features of the species are compared with other closely similar taxa of Adalfia and other naviculoid genera.

Gomphocymbellopsis guijiangensis sp. nov. (Cymbellaceae; Bacillariophyta), a new species from Guangxi Province with comments on associated specimens from Hubei Province, China

Gomphocymbellopsis guijiangensis sp. nov. and G. sp. were collected from the Guijiang River and from fossil deposits of the Jianghan Plain, respectively. The morphology of this new species is described by both light and scanning electron microscopy and compared with G. ancyli, the only other species of the genus Gomphocymbellopsis. G. guijiangensis sp. nov. is characterized by valves that are asymmetrical to the transapical axis and weakly asymmetrical to the apical axis, by the presence of pore fields at the apices, by three differently shaped stigmata, by externally and dorsally deflected distal raphe ends, and by often ventrally deflected proximal raphe ends. Therefore, we describe here G. guijiangensis sp. nov. as species new for science. Concise notes on the associated diatom flora and its ecological preferences are provided.

Achnanthidium lucectorii sp. nov. and A. enigmaticum sp. nov., novel diatoms (Bacillariophyta, Achnanthidiaceae) from Texas, U.S.A.

Two new species, Achnanthidium lucectorii sp. nov., belonging to the A. minutissimum complex (species with straight terminal raphe ends), and A. enigmaticum sp. nov., within the A. pyrenaicum complex (species with hooked terminal raphe fissures), are described from Texas, U.S.A. utilizing light and scanning electron microscopy. Achnanthidium lucectorii sp. nov. has a raphe valve with striae located toward the apices composed of polygonal areolae, a marked stauros, a non-expanded raphe fissure, with straight (non-dilated) proximal ends, and distal ends extending onto the valve mantle. Internally, its raphe valve is flat, the proximal ends of the raphe end in small capitate expansions, and the distal ends terminate in low helictoglossae that fuse with the apices by a low apical siliceous thickening. In turn, its sternum valve is unique in that it is mostly flat in inner view, except at the central nodule, which is slightly raised. In turn, A. enigmaticum sp. nov. externally has a raphe valve with raphe distal ends shaped like a closed hook, at these ends the raphe slit surfaces at the valve face/mantle junction; its axial area is raised in external and internal views, with the virgae and striae in a lower position. These and other traditionally considered features are compared in detail with taxa morphologically similar to each of the new species. The significance of these features is discussed based on a literature survey, and the implications of considering the valve surface topography and the external and internal details of the raphe and central area are assessed. The latter, in favor of a continued morphological exploration of Achnanthidium until molecular studies are appropriately integrated into current morphological approaches used in the taxonomy of the genus.

Study of terrestrial diatoms in corticolous assemblages from deciduous trees in Central Europe with descriptions of two new Luticola D.G.Mann taxa.

Although many studies have examined the algae associated with various habitats in tree trunks, the diatoms in these environments are still poorly studied. Studies of corticolous algae mainly focus on green algae and cyanobacteria, which are usually immediately visible, while diatoms are mostly overlooked or not reported. During the research, 143 species of diatoms were identified, including two new representatives of the genus Luticola: L.bryophilasp. nov. with relatively large central area and short distal raphe endings and L.confusasp. nov. characterized by the presence of small depressions on central raphe endings. Both are described herein based on light and scanning electron microscopy observations and compared to similar taxa based on literature data. Basic morphological data for almost all the diatom taxa are noted, and their habitat requirements, and photographic documentation are also presented. The present research showed that the occurrence of diatom assemblages on tree trunks is influenced by various factors like host tree species, the area where the host tree grows, and the availability of suitable microhabitats within the trunk. However, the species composition of this assemblages depends mainly on the tree species.

The diatom genus Humidophila (Bacillariophyta) in an historic Delogne sample with the description of 2 new species

ABSTRACT During the analysis of a voucher sample from Frahan (Belgium) collected by the Belgian diatomist Charles-Henri Delogne, seven species from the genus Humidophila (Bacillariophyta) have been observed. Two species could not be identified using the currently available literature and are described as new to science. Humidophila delognei sp. nov. has always been identified in the past as H. contenta, but based on recent analysis of the original type material of the latter, it was clear that the currently accepted concept of the species was wrong. The new species is characterised by parallel valve margins, a linear valve outline, a distinct central fascia and T- or Y-shaped raphe endings. The other new species, H. aspera sp. nov., has undulating valve margins and distinct, though irregular siliceous markings in the central and axial area. The sample from Frahan was also indicated in 1885 by Henri Van Heurck as being the original material for the newly described species Humidophila (Navicula) flotowii, long considered a synonym of H. perpusilla. Both species can, however, be separated based on a different length/width ratio, with H. flotowii showing more slender, elongated valves. Other Humidophila species in the sample include H. contenta, H. laevissima, H. perpusilla and H. simplex. Navicula fragilarioides, a new name once introduced for Fragilaria laevissima, the basionym of H. laevissima, is lectotypified based on an original Krasske slide.

Xenobennettella coralliensis a new monoraphid diatom genus characterized by the alveolate sternum valve with cavum, observed from coral reef habitats.

During a survey of benthic diatoms from the coral reefs of the Indian Ocean (Scattered Islands) and Pacific Ocean (Tuamotu Archipelago), an interesting monoraphid diatom was observed and examined by light microscopy and various electron microscopy methods including Focus Ion Beam milling. Our thorough analysis revealed the similarity of this diatom to Bennettella R.W.Holmes, which we reference in the name: Xenobennettella Witkowski & Riaux-Gobin gen. nov., with Xenobennettella coralliensis Witkowski & Riaux-Gobin sp. nov. as the generitype. The type habitat for this new species is the sublittoral coral reef of Juan de Nova in the Mozambique Channel. The sternum valve of the new genus is characterized by an alveolate ultrastructure with the rim of the alveola opening along the valve margin, resembling the sternum valve of Bennettella. Internally, Xenobennettella differs from the latter by possessing a cavum (horseshoe-shaped chamber) on one side of the valve, in a central axial position. The raphe valve of Xenobennettella has small, marginal, apically elongate chambers, which are internally delineated by transapical ribs that are very similar to Bennettella. However, the raphe in the new genus is different from the latter, resembling some Cocconeis and Planothidium with internal raphe endings bent in the opposite direction, while resembling some Planothidium taxa externally by ending on the apical part of the mantle. This contrasts to Bennettella, which has a unique raphe system, with external raphe endings below the apices, a prominent axial structure and a transapically expanded central area. Likewise, the external surface of Bennettella is different from that of the new genus with a complex mantle structure and biseriate striae. In Xenobennettella, the valve mantle of the raphe valve is simple and perforated by areola. The transapical striae occur in the valve margin and the axial area is ornamented along its course with a single row of densely packed areola on both sides. The characteristics of the raphe valve and alveolate sternum valve place the new genus among the Achnanthidiaceae.

Planoplatessa gen. nov.-A New, Neglected Monoraphid Diatom Genus with a Cavum.

A new monoraphid diatom genus, Planoplatessa gen. nov., is described on the basis of a detailed morphological investigation using light and scanning electron microscopy. We transferred Achnanthes joursacensis Héribaud, a species described from fossil deposits in France, to our new genus. We investigated material from Mongolia from Recent populations. This taxon is known from fossils to Recent across the Holarctic. Achnanthes joursacensis was previously transferred to the genera Planothidium and Platessa, but the morphology of A. joursacensis does not share all morphological features with these two genera. We discuss important morphological features for the delimitation of monoraphid genera based on careful morphological and molecular investigations we presented previously. Planoplatessa gen. nov. as a genus is characterized by having uniseriate striae on both the raphe and the rapheless valves, a cavum in rapheless valves only, and straight distal raphe ends on the valve face.

Humidophila manipurensis sp. nov. and the first record of Humidophila bigibba (Hustedt) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot et Kopalová from Northeast India

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.

Four new species of the genus Lacustriella (Bacillariophyta) from Lake Baikal

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.

A new freshwater species Achnanthidiumkangdingnese (Bacillariophyta, Achnanthidiaceae) from Sichuan Province, China.

A new freshwater diatom species, Achnanthidiumkangdingnese Yu, You & Wang, sp. nov. from Sichuan Province, China, is described. The morphology of this species was analyzed with scanning electron microscopy (SEM) and light microscopy (LM). A.kangdingnese belongs to the A.initium-like subgroup, which has external distal raphe ends curved in opposite directions of the valve. The main characteristics of A.kangdingnese are its linear shape, rounded apices and transpically-elongated areolae on the both valves. The central area is well defined with one or two spaced striae of the raphe valve. And on the internal valve, areolae are occluded by hymens perforated by delicate slits, and each hymen is closely joined with the adjacent hymen. We compared the new species with other similar species of Achnanthidium, A.kangdingnese is considered to be sufficiently different from other similar species based on valve outline, shape of the axial and center areas, and striae density. The new species is known only from its type locality, a mountain lake in Kangding County.

A new species of Fogedia (Bacillariophyceae) from tidal flats of Northeast Asia

The genus Fogedia was first established in 1997 based on Navicula giffeniana as a type species. The important features of the genus were the presence of lateral area, the location of the internal raphe fissure, and the simple apical raphe endings. Later, the generic description of Fogedia has been emended with the reports of four new species to the science having the genus to include twelve members in total. A thirteenth member of the genus has been observed in tidal flats of the Yellow Sea, and here we describe the species as Fogedia orientalis sp. nov. based on observations with the light (LM) and scanning electron microscope (SEM). Regional distribution of the species in the Northeast Asia is also discussed. The new Fogedia species is morphologically similar to F. densa in terms of small cell size as wells as the absence of a lateral area, however, the density and pattern of striae are clearly different from each other. Morphological characteristics and global occurrences of the thirteen Fogedia species has been provided.