Stria Density Research Articles

Chlorophyllase (PsCLH1) and light-harvesting chlorophyll a/b binding protein 1 (PsLhcb1) and PsLhcb5 maintain petal greenness in Paeonia suffruticosa ‘Lv Mu Yin Yu’

IntroductionGreen flowers are not an adaptive trait in natural plants due to the challenge for pollinators to discriminate from leaves, but they are valuable in horticulture. The molecular mechanisms of green petals remain unclear. Tree peony (Paeonia suffruticosa) is a globally cultivated ornamental plant and considered the ‘King of Flowers’ in China. The P. suffruticosa ‘Lv Mu Yin Yu (LMYY)’ cultivar with green petals could be utilized as a representative model for understanding petal-specific chlorophyll (Chl) accumulation and color formation. ObjectivesIdentify the key genes related to Chl metabolism and understand the molecular mechanism of petal color changes. MethodsThe petal color parameter was analyzed at five developmental stages using a Chroma Spectrophotometer, and Chl and anthocyanin accumulation patterns were examined. Based on comparative transcriptomes, differentially expressed genes (DEGs) were identified, among which three were functionally characterized through overexpression in tobacco plants or silencing in ‘LMYY’ petals. ResultsDuring flower development and blooming, flower color changed from green to pale pink, consistent with the Chl and anthocyanin levels. The level of Chl demonstrated a similar pattern with petal epidermal cell striation density. The DEGs responsible for Chl and anthocyanin metabolism were characterized through a comparative transcriptome analysis of flower petals over three critical developmental stages. The key chlorophyllase (PsCLH1) and light-harvesting chlorophyll a/b binding protein 1 (PsLhcb1) and PsLhcb5 influenced the Chl accumulation and the greenness of ‘LMYY’ petals. ConclusionPsCLH1, PsLhcb1, and PsLhcb5 were critical in accumulating the Chl and maintaining the petal greenness. Flower color changes from green to pale pink were regulated by the homeostasis of Chl degradation and anthocyanin biosynthesis. This study offers insights into underlying molecular mechanisms in the green petal and a strategy for germplasm innovation.

The genus Brachysira (Brachysiraceae, Bacillariophyceae) in the Arctic with the description of two new species

ABSTRACT Two unknown diatoms belonging to the genus Brachysira were found during a survey of the moss-inhabiting diatom flora in Canada, Greenland, Iceland and Spitsbergen. Detailed light and scanning electron microscopy revealed sufficient morphological differentiation in valve dimensions and shape, striae density, and ultrastructure for them to be described as new species. The description of Brachysira louiseboydiana sp. nov. and B. hutchisoniana sp. nov. brings the total number of Brachysira species globally to 132. Formal descriptions are presented, each illustrated by light and scanning electron micrographs, and the new species are compared with similar Brachysira taxa worldwide. Additionally, four previously described species which were also observed in the Arctic mosses are discussed. Our findings contribute to a better understanding of the Arctic terrestrial diatom flora.

A new freshwater species Achnanthes licunese sp. nov. (Achnanthaceae, Bacillariophyta) from pebbles of Licun River, Shandong Province, China

A new freshwater diatom species, Achnanthes licunese sp. nov., was found on pebble samples collected from Licun River in Shandong Province, China. The various taxonomic characteristics of Achnanthes licunese sp. nov. is observed under light and scanning electron microscope. The living cells of A. licunese sp. nov. possesses two chloroplasts. Its valves exhibit a linear to linear-lanceolate outline, slightly constricted in the middle part, with uniseriate striae. The central area of the raphid valves is expanded into a linear and thickened stauros, and the raphe is filiform. On the araphid valves, there is no central area, and the axial area (sternum) is located in the valve margin. The valve of the A. licunese sp. nov. possesses the marginal spines, but no marginal ridge and terminal orbiculi. By comparing the new species with similar Achnanthes species, A. licunese sp. nov. was confirmed to be sufficiently different regarding valve size, striae density, and the presence of marginal spines. The discovery of this species increases the diversity of freshwater diatoms.

A new Actinella species (Eunotiaceae, Bacillariophyta) from the Yangambi Biosphere Reserve, Democratic Republic of the Congo

Background and aims – Actinella species from Central Africa are only rarely reported. The acid waters from many stream and small rivers in the Congo Basin form a potential environment for species of this genus. We studied several samples from the region of Yangambi to confirm whether species belonging to this genus are present. Material and methods – Samples for diatom investigation were collected in several streams and small rivers (Moni, Ngima, and Libongo), in the tropical rainforest in the Yangambi Biosphere Reserve, Tshopo Province, Democratic Republic of the Congo. The samples were prepared to obtain permanent microscope slides for light microscopy studies using standard methods and cleaned material for scanning electron microscopy. Key results – A novel Actinella was observed in the studied samples. The taxon was compared to other species such as A. disjuncta, A. lange-bertalotii, A. modesta, A. pereunotioides, and A. pseudohantzschia, although the new species morphologically resembles most A. eunotioides, a species discovered in the Amazon basin in Brazil, and A. eunotioides var. minor, described in 1966 from the Central African Republic. The taxon observed in our material differs from A. eunotioides mainly in the valve dimensions, being much smaller, and the higher density of the marginal spines. Stria density also tends to be coarser. The valve length of A. eunotioides var. minor, on the other hand, corresponds with the smallest valves of our taxon but the valves are narrower, with a higher stria density. The ventral margin is slightly convex, while in the new taxon it is slightly concave. Moreover, in the original description of A. eunotioides var. minor, the absence of spines is mentioned, while they are present on the valves in the materials we investigated. Based on the observed morphological differences, we consider the taxon recorded in the streams and small rivers in the Yangambi Biosphere Reserve distinct from A. eunotioides and its var. minor and subsequently, we describe Actinella kufferathiana as a species new to science.

Gyrosigma dongtingense sp. nov. (Bacillariophyta) from Dongting Lake, China

Dongting Lake is China’s second largest freshwater lake; some new diatom species have been described from this lake recently. The current study describes a new diatom species from this lake, Gyrosigma dongtingense sp. nov. Gyrosigma dongtingense sp. nov. belongs to the section Strigiles sensu H. Peragallo and it is characterized by: 1) its large cell size (valves are 161–218 μm long and 24–29 μm wide), 2) having two curvatures for each half of its raphe sternum, 3) the transverse stria density (12–14 in 10 μm) lower than the longitudinal stria density (16–18 in 10 μm), 4) both the external proximal raphe fissures deflecting towards the convex side of each corresponding half-valve, 5) T-shaped internal proximal raphe fissures, and 6) a prominent axial costa presents along the primary side of the raphe sternum. The isomorphism and dimorphism of the external proximal raphe fissures are reviewed, and similar taxa are discussed.

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.

Morphology and molecular phylogeny of two marine diatom species, Falcula cf. media and F. rectangularis sp. nov. (Bacillariophyta) from Japan

ABSTRACT Two members of the marine diatom genus Falcula, which has been little known for a long time, were found from the surface of some Japanese seaweeds; one was assigned to F. cf. media and the other was described as a new species, F. rectangularis sp. nov. Aside from the arcuate valves and slit-like apical fields, typical of the genus, detailed morphological observations using light and scanning electron microscopy revealed resemblance between F. cf. media and F. rectangularis in areolae, stria density and lack of costae. However, the two species can be distinguished based on several morphological features, including the valve length, plastid arrangement, and frustules in girdle view. A three-gene molecular phylogeny recovered these two species as monophyletic with a high interspecific rbcL difference, which in turn were sister to the clade containing taxa that belong to the orders Cyclophorales and Protoraphidales with low support. The members in this poorly supported assemblage share apical fields composed of slits. The two species of Falcula were phylogenetically distinct from Pseudofalcula hyalina, a member previously assigned to Falcula.

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.

Distribution and morphology of the diatom genus Olifantiella Riaux-Gobin & Compère in Indonesian and Australian waters, including the description of O.gondwanensis sp. nov.

Samples from coastal tropical waters of Central Sulawesi, Bangka Island and Bawean Island in Indonesia and from the Great Barrier Reef at Fitzroy Island in Queensland, Australia were analysed for species composition of diatom assemblages with a focus on Olifantiella. Whereas samples from Fitzroy Island littoral in Australia retrieved only one species of Olifantiella, in Poso Bay, Indonesia, we observed at least six species. All established taxa were documented with light (LM) and scanning electron microscope (SEM) and principal component analysis (PCA) analysis was used to compare the species, based on the basic valve parameters of length, width, length to width ratio and striae density. A new species of the genus Olifantiella, O.gondwanensis is described from Australia. In addition, we showed the distinct nature of O.pilosellavar.rhizophorae permitting to species status. Particular attention is placed on girdle bands in this genus.

Quantitative Morphometric Analysis of Morphologically Similar Species of Fragilaria (Fragilariaceae, Bacillariophyta) Allows Detection of Non-Indigenous Taxa: A Case Study from Lake Ladoga (North of European Russia)

In Lake Ladoga (northwestern Russia), we found a diatom, putatively Fragilaria sublanceolata-baikali, an endemic species from Lake Baikal (southeastern Siberia, Russia). To determine whether this population matches a previously recognized species from Lake Baikal and assess how it differs from other similar Fragilaria taxa, we studied the valve morphology of three morphologically similar Fragilaria populations (the putative F. sublanceolata-baikali, F. pectinalis and F. perminuta) sampled in Lake Ladoga, along with a population of F. sublanceolata-baikali sampled in Lake Baikal. We used light and scanning electron microscopy with a combination of traditional and geometric morphometric methods. To analyze covariation between the valve shape and size (i.e., allometry), we examined differences in the ontogenetic–allometric trajectories at both the interspecific and intraspecific levels. In addition, the effect of size correction of the valve shape on species differentiation was tested. Traditional morphometrics revealed that F. sublanceolata-baikali is distinguished from F. pectinalis and F. perminuta by valve length, while F. pectinalis and F. perminuta are distinguished by striae density. All three species of Fragilaria showed separate and parallel allometric trajectories. In contrast, the two populations of F. sublanceolata-baikali were on a common allometric trajectory, indicating the conspecificity between these populations. Prior to allometric correction, geometric morphometrics was not able fully discriminate between the three Fragilaria species. After allometric correction, the three Fragilaria species were clearly separated in a size-corrected morphospace, whereas the two populations of F. sublanceolata-baikali formed a tightly overlapping group. Thus, we conclude that geometric morphometrics can reliably distinguish between these morphologically similar species of Fragilaria, but only after accounting for allometric shape variation. Our study confirmed morphological similarity between the two geographically distant populations of F. sublanceolata-baikali, which indicates that this taxon can be considered as invasive in Lake Ladoga.

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.

Three new cymbelloid species in the genera Cymbella, Cymbopleura and Delicatophycus from the mineral spring Crvena Voda near Skopje, Republic of North Macedonia

Mineral springs are unique habitats frequently inhabited by specific diatom species with restricted distributions. In the mineral spring Crvena Voda near Skopje, three cymbelloid taxa were observed, whose morphological characteristics differ from already known taxa. They are described here as: Cymbella parahelvetica sp. nov., Cymbopleura angustilanceolata sp. nov. and Delicatophycus fontinalis sp. nov. Cymbella parahelvetica sp. nov. is characterized by the absence of an apical pore field at the valve ends and by very densely arranged striae. Cymbopleura angustilanceolata sp. nov. can be distinguished from other Cymbopleura species by the valve outline, the shape of the central area and the stria density. Delicatophycus fontinalis sp. nov. can be differentiated from similar species by its strongly arched dorsal margin, its valve width and stria density.

Description of Gomphonella saldanensis sp. nov. (Bacillariophyceae) from hydromagnesite stromatolites in Salda Lake, Turkey

Lake Salda has a unique environment due to the presence of hydromagnesite stromatolites. Samples collected from the stromatolites contained a new diatom species, Gomphonella saldanensis sp. nov., which is described based on light and scanning electron microscopy. The main character of the taxon is its linear-lanceolate outline with a rostrate headpole and narrowly rounded footpole. The striae are strongly radiate mid-valve, becoming parallel to slightly radiate towards the poles. Elliptical Fourier and Linear Discriminant analyses indicate that there are different shape forms within the same taxon. Based on LM observations, G. saldanensis is similar to Gomphonema lagerheimii f. simplex, G. geisslerae, Gomphonella calcarea, G. olivacea, G. acsiae and G. coxiae. However, G. lagerheimii f. simplex differs with slightly radiate striae throughout the valve. Gomphonella geisslerae has a slightly undulate raphe and linear apices. Larger specimens of G. acsiae are lanceolate, clavate in smaller specimens. The remaining Gomphonella species, G. calcarea, G. coxiae and G. olivacea have broader outlines and lower stria densities.

Chamaepinnularia taihangensis sp. nov. (Bacillariophyceae), a new diatom species from Taihang Valley, Shanxi province, China

A new species was discovered in Taihang Valley, Shanxi province, China. It shared the typical characteristics of the genus Chamaepinnularia, such as chambered striae, vela-covered areolae and small frustules. Valves of Chamaepinnularia taihangensis sp. nov. are linear-lanceolate with capitate apices. Valve margins showed distinct triple curvatures in light microscopy. Axial area and central area narrow, rhombic. The new species was compared with the four related taxa, C. hassiaca, C. justa, C. krookiformis and C. soehrensis. These species differed from the new species in valve outline, valve size, stria density and the shape of the central area. The details of the valves as shown by light and scanning electron microscopy are described. This new species occurs in benthic and epiphyte habitats. We discuss the ecological breadth and systematic position of the genus Chamaepinnularia.

A critical analysis of the Fragilaria vaucheriae complex (Bacillariophyta) in Europe

<i>Fragilaria vaucheriae</i> is one of the most common <i>Fragilaria</i> species in Europe, typically reported from impacted, eutrophic water bodies. Despite its ubiquity, the species presents a broad morphological variability, urging a complete taxonomic revision based on the analysis of the morphology of a substantial number of historic and recent populations. In the present study, type material of <i>Exilaria vaucheriae</i>, <i>Fragilaria rinoi</i>, and<i> Echinella fasciculata </i>&beta; [var.] <i>truncata</i> was investigated using LM and SEM observations, together with more than 10 historic and recent populations. The results based on these comparisons show that <i>Fragilaria vaucheriae</i> is most likely a rather rare <i>Fragilaria</i> species in Europe and that most populations should be identified as <i>Fragilaria truncata</i>, a new combination made here based on <i>Echinella fasciculata </i>&beta; <i>truncata</i>. The observations made in this study also resulted in the description of several new species, often with distinct ecologies and distributions: <i>Fragilaria catenarinoi</i> Van de Vijver et D.M.Williams sp. nov., <i>F. kellyana</i> Van de Vijver, D.M.Williams et Ector sp. nov., <i>F. landnama</i> Van de Vijver et Iris Hansen sp. nov., <i>F. thingvellirensis</i> Van de Vijver et G.S.JĂłnsson sp. nov., <i>F. vandekerckhoveana</i> Van de Vijver sp. nov., <i>F. vaucheriaefalsa</i> Van de Vijver et D.M.Williams sp. nov. and <i>F. vaucheriaerobusta</i> Van de Vijver, C.E.Wetzel et Ector sp. nov. Important features to discriminate the different species include valve outline (linear versus lanceolate), the presence of 'shoulders' beyond the apices, the presence of striae (and the formation of colonies), the stria density and the shape and structure of the central area. Using an analysis of the associated diatom flora, the ecological preferences of each taxon are briefly discussed.

The genus Craspedostauros E.J.Cox (Bacillariophyta) on the coasts of Livingston Island, Maritime Antarctica

During a survey of diatoms present in tidal pools on the coasts of Livingston Island (South Shetland Islands), we found several populations, belonging presumably to the Antarctic endemic Craspedostauros laevissimus. Further analyses using light microscopy revealed that the populations show differences in stria density. Following scanning electron microscopy observations, only part of the investigated populations could be assigned to C. laevissimus, whereas the others are sufficiently morphologically different based on stria density and their cribrate areolae structure to be described as a new species: Craspedostauros confusus sp. nov. The new taxon is compared with known, morphologically similar, Craspedostauros taxa. The paper presents morphological and ecological data for both taxa discussed in the study. A detailed survey of the early Antarctic literature showed that the Craspedostauros taxa in Antarctica have convoluted taxonomic histories and that the new taxon has likely been hidden for long within the variability of C. laevissimus.

Halamphora minima (Catenulaceae, Bacillariophyta), new brackish diatom species from the mudflat in Hampyeong Bay, Korea

The diversity of benthic diatoms living in the tidal flats is thought to be very high but has been somewhat marginalized from our main concern. We propose a new species, Halamphora minima sp. nov. isolated as monoclonal cultures from a tidal mudflat based on light and scanning electron microscopy and molecular analysis. This species is the smallest known species of the genus Halamphora to date. Other main characteristics that distinguish this species are the biseriate separated by strongly developed costa for the majority of the valve face, and density of dorsal striae. Phylogenetic analysis of the chloroplast ribulose bisphosphate carboxylase large chain gene showed that H. minima seems to be related to H. foramina, H. sydowii and H. tumida, but the phylogenetic location of H. minima was not clear due to the low bootstrap.

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.

Staurophora ouniangaensis sp. nov. (Bacillariophyceae, Anomoeoneidaceae), a new diatom from the Ounianga Lakes in the Sahara, Chad

Modern diatom assemblages were investigated in the Ounianga Lakes located in the driest part of the Chadian Sahara. These lakes still exist today due to groundwater seepage. They contain a variety of diatom species, one of which could not be identified. Here we describe a new species of Staurophora, S. ouniangaensis sp. nov. based on detailed light and scanning electron microscopy observations. The new taxon presents all morphological characters attributed to this genus and differs from other Staurophora species mainly by its specific valve outline and the slightly twisted frustules along the transapical axis. We compared this new species with the morphologically resembling Cymbella obtusa which was reported from Chad. The latter taxon has a much coarser stria density than our newly described species. Staurophora ouniangaensis sp. nov. supports that Staurophora species prefer inland saline environments. Indeed, in the Ounianga lakes, the new species was mainly observed in mesosaline to hypersaline waters.

Two new species of Plagiostriata (Bacillariophyaceae) from sand sediments of southern China

This study describes two new species of Plagiostriata: P. xiapuensis sp. nov. and P. pingtanensis sp. nov., both collected in the intertidal zone of Fujian Province, China. This is the first record of species in the genus Plagiostriata in China. The morphological characteristics of the two new species are discussed in detail using light and scanning electron microscopy. Plagiostriata xiapuensis sp. nov. is characterized by its lower stria density and simple volae-covered areolae compared to the higher stria density, small and complex volae–covered areolae in P. pingtanensis sp. nov. The morphological characteristics of these two species significantly differ from those of P. goreensis and P. baltica in sternum and areolae features, which is also discussed herein.