During this investigation, sixteen species from the genus
were found in a shallow bay (near Oimur, Kabansky District) located on the eastern shore of Lake Baikal. Eleven of these taxa have been ...described previously. Five species are described as new to science. We provide ecological information about these
species, including their distribution within and outside Lake Baikal, and compare and contrast the new taxa with morphologically similar congeners. The diversity of morphologies present in Lake Baikal among the
species suggests there has been both in-lake speciation as well as the introduction of various groups of species. The idea that Lake Baikal may support a high number of endemics by their partitioning niches based on depth is supported by the different groups of gomphonemoid diatoms present.
The current article describes Navicula vanseea sp. nov. , a new species of diatom from Lake Van, a highly alkaline lake in Eastern Anatolia (Türkiye). The description is based on light and scanning ...electron microscopy performed on two monoclonal cultures. The complete nuclear rRNA clusters and plastid genomes have been sequenced for these two strains and the complete mitogenome for one of them. The plastome of both strains shows the probable loss of a functional ycf35 gene. They also exhibit two IB4 group I introns in their rrl , each encoding for a putative LAGLIDADG homing endonuclease, with the first L1917 IB4 intron reported amongst diatoms. The Maximum Likelihood phylogeny inferred from a concatenated alignment of 18S , rbcL and psbC distinguishes N. vanseea sp. nov. from the morphologically similar species Navicula cincta and Navicula microdigitoradiata .
Çanakkale is located in Western Anatolia, a region known for extensive mining in the country. In this study, three new species: Nitzschia arslaniana sp. nov., Nitzschia efeiana sp. nov., and ...Nitzschia szaboiana sp. nov. are described from highly acidic environments in Çanakkale. In morphology, Nitzschia arslaniana is similar to Nitzschia inconspicua but Nitzschia inconspicua is broader, with a lower fibulae density. Nitzschia efeiana is similar to Nitzschia. bremensis, Nitzschia capitellata, Nitzschia homburgiensis, Nitzschia hybrida, Nitzschia palustris, and Nitzschia pellucida. However, Nitzschia efeiana has variable fibulae widths, thickened virgae on its external valve face, and an elevated ridge on the valve margin opposite the keel. Nitzschia szaboiana is similar to Nitzschia pusilla, but the later taxon has a higher striae density. This study highlights the unique species diversity of extreme environments, including anthropogenic extreme environments, by describing three new taxa in the same genus.
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.
Craspedostauros
E.J. Cox is a diatom genus comprising 17 taxa reported from various regions of the world. While many species of
Craspedostauros
are epibiontic, the taxa have variable ecological ...preferences. In this study we formally describe
Craspedostauros nazmii
sp. nov.
, an epilithic species discovered along the Turkish Black Sea Coast, based on light and scanning electron microscopy.
Craspedostauros nazmii
sp. nov.
is characterized by valves that are lanceolate to narrowly lanceolate, slightly constricted near the apices with uniseriate, parallel throughout the whole valve, transapical striae and and the presence of an apical silica flap. The areolae are distributed over the valve face and the mantle. The differences and similarities between
C. nazmii
sp. nov.
and established species of
Craspedostauros
are discussed. Based on shape and morphometrics, the most similar species is
Craspedostauros capensis
, but it is easily distinguished from
C. nazmii
sp. nov.
by its lack of an apical silica flap.
In this article we describe Nitzschia anatoliensis Górecka, Gastineau & Solak sp. nov., an example of a diatom species inhabiting extreme habitats. The new species has been isolated and successfully ...grown from the highly alkaline Van Lake in East Turkey. The description is based on morphology (light and scanning electron microscopy), the sequencing of its organellar genomes and several molecular phylogenies. This species could easily be overlooked because of its extreme similarity to Nitzschia aurariae but molecular phylogenies indicate that they are only distantly related. Furthermore, molecular data suggest that N. anatoliensis may occur in several alkaline lakes of Asia Minor and Siberia, but was previously misidentified as Nitzschia communis. It also revealed the very close genetic proximity between N. anatoliensis and the endosymbiont of the dinotom Kryptoperidinium foliaceum, providing additional clues on what might have been the original species of diatoms to enter symbiosis.
Background and aims
– Kützing separated the genus
Achnanthidium
from the genus
Achnanthes
based on two species:
Achnanthes minutissima
and
Achnanthidium microcephalum
. These two genera were ...distinguished by the presence of stalks in the
Achnanthes
genus and their absence in
Achnanthidium
. Before electron microscopy, the difference between
Achnanthes
and
Achnanthidium
was not clear, especially in
Achnanthidium minustissimum
sensu lato. The aim of the study is to describe three new species of
Achnanthidium
from Lake Salda.
Material and methods
– Lake Salda is located in southwestern Anatolia, in Turkey. The diatoms were collected seasonally from four stations in the lake between 2016 and 2020, from different substrata (epipelic, epiphytic, and epilithic).
Key results
– Three new species belonging to the genus
Achnanthidium
have been found in Lake Salda, Turkey. Based on the morphological observations, all new taxa are part of the
Achnanthidium minutissimum
complex.
Achnanthidium barlasii
sp. nov. and
A. dumlupinarii
sp. nov. show a high degree of similarity to each other, but can be separated based on valve outline and a denser areolation, especially in striae close to the apices of the raphe valve. Both species can be distinguished from
A. minutissimum
based on more separate apices and less elliptic valves. In the case of
A. dumlupinarii
sp. nov., large specimens show slight undulations of the valve, which is a unique feature.
Achnanthidium anatolicum
sp. nov. is the most characteristic based on its valve width, broadly rounded valve apices, and almost straight valves in girdle view. All newly described
Achnanthidium
species can be found in lentic environments, with alkaline water and high calcium ion content.
Conclusion
– The newly described taxa occurred in the unique habitat of a soda lake. The environment of the lake is highly alkaline, rich in magnesium and calcium, and derived from limestone and dolomitic limestone rocks.
In this study, the diatoms of three alternative habitats (epilithon, epiphyton and artificial sub-strate) were compared to understand the differences in composition on artificial and natural ...sub-strates. For this purpose, the samples were collected weekly between 11th August and 2nd Septem-ber 2016 at a sampling site in a shallow marine lake, Mrtvo More (Dead Sea) on Lokrum Island near Dubrovnik (South Adriatic, Croatia). In addition to detailed light microscopic analysis, ultrastructural analysis of benthic diatoms from Lake Mrtvo More was performed for the first time using scanning electron microscopy (SEM). A total of 97 taxa were identified in 12 samples. Cocconeis scutellum Ehrenberg and Halamphora coffeiformis (C.Agardh) Levkov were the most frequent taxa in the samples. Shannon-Wiener diver-sity index (H’) values varied from 1.78 (in September on Padina sp.) to 4.52 (in August on glass). According to non-metric multidimensional scaling ordination, there were two groups: epilithon and artificial glass substrate as Group1 and macroalgae as Group2. The results of the analysis showed that the diatom communities developing on artificial sub-strates accurately correspond to the diatom community of a rock substrate and thus can be used as a representative alternative tool for studies of epilithic diatoms in further experiments.
Kako bi se razumjele razlike između naseljavanja na umjetnim i prirodnim podlogama, u ovom istraživanju uspoređivani su sastavi dijatomeja s tri alternativna staništa (epiliton, epifiton i umjetni supstrat). U tu svrhu uzorci su sakupljani tjedno između kolovoza i rujna 2016. na jednoj lokaciji u plitkom morskom jezeru Mrtvo More na otoku Lokrumu kod Dubrovnika (Južni Jadran, Hrvatska). Osim detaljne analize svjetlosnim mikroskopom, po prvi put je provedena i ultrastrukturna analiza bentoskih dijatomeja iz jezera Mrtvo More pomoću elektronske mikroskopije (SEM). U 12 uzoraka identificirano je ukupno 97 vrsta dijatomeja. Vrste Cocconeis scutellum Ehrenberg i Halamphora coffeiformis (C.Agardh) Levkov bile su najčešće vrste u uzorcima. Vrijednosti Shannon-Wiener (H’) indeksa varirale su od 1,78 (u rujnu na vrsti Padina sp.) do 4,52 (u kolovozu na staklu). Prema nMDS ordinaciji, razlikuju se dvije skupine zajednica bentoskih dijatomeja: epiliton i umjetna staklena podloga kao Grupa 1 i makroalge kao Grupa 2. Rezultati analize pokazali su da zajednice bentoskih dijatomeja koje se razvijaju na umjetnim podlogama, odgovaraju dijatome-jskoj zajednici kamene podloge i da se stoga mogu koristiti kao reprezentativni alternativni alat za proučavanje epilitskih dijatomeja u daljnjim eksperimentima.
We sequenced the chloroplast genome of Poterioochromonas malhamensis (Pringsheim) R.A.Andersen strain SZCZR2049, which originates from Van Lake in Turkey. This genome is 133,923 bp long, and like ...those currently available for six phototrophic chrysophytes, it displays a long, gene-rich inverted repeat and a very short single-copy region. Compared to its chrysophyte counterparts, the P. malhamensis inverted repeat differs noticeably in gene content and the whole genome is missing 11 protein-coding genes. The maximum likelihood phylogeny inferred from concatenated protein-coding genes positioned P. malhamensis among the chrysophytes sensu lato as sister to the clade containing the Synurales (Synurophyceae) and Chromulinales (Chrysophyceae).
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