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David G. Mann - One of the best experts on this subject based on the ideXlab platform.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
2019Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschia as an independent genus. It is concluded that, while a core of hantzschioid species may exist that can be classified together, corresponding to the traditional understanding of the genus Hantzschia, there is no single morphological feature common to all of them that can be used to diagnose the group and differentiate it from the various hantzschioid lineages that are separate from true Hantzschia and currently placed in e.g. Nitzschia or Cymbellonitzschia. Testing whether a hantzschioid species does or does not belong to Hantzschia will in many cases require molecular evidence. Although the new coastal species does not belong to the same lineage as the type species of Nitzschia, N. sigmoidea, it is described for the moment as N. varelae Carballeira, D.G. Mann & Trobajo, sp. nov., until there is a better understanding of generic limits in the Bacillariaceae following a wider molecular and morphological survey of that family.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
European Journal of Phycology, 2017Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:AbstractA previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschi...
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Symmetry and sex in Bacillariaceae (Bacillariophyta), with descriptions of three new Nitzschia species
European Journal of Phycology, 2014Co-Authors: David G. Mann, Rosa TrobajoAbstract:The large diatom genus Nitzschia and the morphologically similar Hantzschia are currently distinguished on the basis of cell symmetry and division. In Hantzschia, the eccentrically placed raphe systems of the two valves are always on the same side of the frustule (‘hantzschioid’ symmetry), never diagonally opposite (‘nitzschioid’ symmetry). Although some Nitzschia species produce hantzschioid cells, it has previously been thought that these cells never breed true but divide to give one nitzschioid daughter and one hantzschioid daughter. Sublittoral marine epipelon from Loch Goil, W Scotland, contained three undescribed species of Bacillariaceae whose cells were always hantzschioid, but which possessed a valve structure (silica flaps on either side of the raphe, no central raphe endings, a slit-like entrance to the raphe canal that narrows towards the poles, and discrete bar-like fibulae) linking them to N. spathulata and the type species of Nitzschia, N. sigmoidea. They also agreed with these species in c...
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Symmetry and sex in Bacillariaceae (Bacillariophyta), with descriptions of three new Nitzschia species
2014Co-Authors: David G. Mann, Rosa TrobajoAbstract:The large diatom genus Nitzschia and the morphologically similar Hantzschia are currently distinguished on the basis of cell symmetry and division. In Hantzschia, the eccentrically placed raphe systems of the two valves are always on the same side of the frustule (‘hantzschioid’ symmetry), never diagonally opposite (‘nitzschioid’ symmetry). Although some Nitzschia species produce hantzschioid cells, it has previously been thought that these cells never breed true but divide to give one nitzschioid daughter and one hantzschioid daughter. Sublittoral marine epipelon from Loch Goil, W Scotland, contained three undescribed species of Bacillariaceae whose cells were always hantzschioid, but which possessed a valve structure (silica flaps on either side of the raphe, no central raphe endings, a slit-like entrance to the raphe canal that narrows towards the poles, and discrete bar-like fibulae) linking them to N. spathulata and the type species of Nitzschia, N. sigmoidea. They also agreed with these species in chloroplast morphology and auxosporulation and are therefore assigned to Nitzschia as N. dicrogramma, N. brachygramma and N. parkii, spp. nov. Consequently the only type of cell division found in all Hantzschia species (in which a hantzschioid parent cell divides to give two hantzschioid daughters) is not unique to Hantzschia but also occurs in at least one lineage of Nitzschia. ‘Core’ Hantzschia species may nevertheless comprise a monophyletic group, characterized by an unusual kind of internal central raphe endings. Four symmetry categories are now known in Hantzschia and Nitzschia: (1) all cells hantzschioid; (2) hantzschioid and nitzschioid cells in a 2 : 1 ratio; (3) hantzschioid and nitzschioid cells in a 1 : 1 ratio; and (4) all cells nitzschioid. The division pattern seems to be constant within species and may therefore be useful as a taxonomic character above the species level. Hantzschia segmentalis is given its first written description.
Rosa Trobajo - One of the best experts on this subject based on the ideXlab platform.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
2019Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschia as an independent genus. It is concluded that, while a core of hantzschioid species may exist that can be classified together, corresponding to the traditional understanding of the genus Hantzschia, there is no single morphological feature common to all of them that can be used to diagnose the group and differentiate it from the various hantzschioid lineages that are separate from true Hantzschia and currently placed in e.g. Nitzschia or Cymbellonitzschia. Testing whether a hantzschioid species does or does not belong to Hantzschia will in many cases require molecular evidence. Although the new coastal species does not belong to the same lineage as the type species of Nitzschia, N. sigmoidea, it is described for the moment as N. varelae Carballeira, D.G. Mann & Trobajo, sp. nov., until there is a better understanding of generic limits in the Bacillariaceae following a wider molecular and morphological survey of that family.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
European Journal of Phycology, 2017Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:AbstractA previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschi...
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Symmetry and sex in Bacillariaceae (Bacillariophyta), with descriptions of three new Nitzschia species
European Journal of Phycology, 2014Co-Authors: David G. Mann, Rosa TrobajoAbstract:The large diatom genus Nitzschia and the morphologically similar Hantzschia are currently distinguished on the basis of cell symmetry and division. In Hantzschia, the eccentrically placed raphe systems of the two valves are always on the same side of the frustule (‘hantzschioid’ symmetry), never diagonally opposite (‘nitzschioid’ symmetry). Although some Nitzschia species produce hantzschioid cells, it has previously been thought that these cells never breed true but divide to give one nitzschioid daughter and one hantzschioid daughter. Sublittoral marine epipelon from Loch Goil, W Scotland, contained three undescribed species of Bacillariaceae whose cells were always hantzschioid, but which possessed a valve structure (silica flaps on either side of the raphe, no central raphe endings, a slit-like entrance to the raphe canal that narrows towards the poles, and discrete bar-like fibulae) linking them to N. spathulata and the type species of Nitzschia, N. sigmoidea. They also agreed with these species in c...
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Symmetry and sex in Bacillariaceae (Bacillariophyta), with descriptions of three new Nitzschia species
2014Co-Authors: David G. Mann, Rosa TrobajoAbstract:The large diatom genus Nitzschia and the morphologically similar Hantzschia are currently distinguished on the basis of cell symmetry and division. In Hantzschia, the eccentrically placed raphe systems of the two valves are always on the same side of the frustule (‘hantzschioid’ symmetry), never diagonally opposite (‘nitzschioid’ symmetry). Although some Nitzschia species produce hantzschioid cells, it has previously been thought that these cells never breed true but divide to give one nitzschioid daughter and one hantzschioid daughter. Sublittoral marine epipelon from Loch Goil, W Scotland, contained three undescribed species of Bacillariaceae whose cells were always hantzschioid, but which possessed a valve structure (silica flaps on either side of the raphe, no central raphe endings, a slit-like entrance to the raphe canal that narrows towards the poles, and discrete bar-like fibulae) linking them to N. spathulata and the type species of Nitzschia, N. sigmoidea. They also agreed with these species in chloroplast morphology and auxosporulation and are therefore assigned to Nitzschia as N. dicrogramma, N. brachygramma and N. parkii, spp. nov. Consequently the only type of cell division found in all Hantzschia species (in which a hantzschioid parent cell divides to give two hantzschioid daughters) is not unique to Hantzschia but also occurs in at least one lineage of Nitzschia. ‘Core’ Hantzschia species may nevertheless comprise a monophyletic group, characterized by an unusual kind of internal central raphe endings. Four symmetry categories are now known in Hantzschia and Nitzschia: (1) all cells hantzschioid; (2) hantzschioid and nitzschioid cells in a 2 : 1 ratio; (3) hantzschioid and nitzschioid cells in a 1 : 1 ratio; and (4) all cells nitzschioid. The division pattern seems to be constant within species and may therefore be useful as a taxonomic character above the species level. Hantzschia segmentalis is given its first written description.
Maxim Kulikovskiy - One of the best experts on this subject based on the ideXlab platform.
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Biogeography of the cosmopolitan terrestrial diatom Hantzschia amphioxys sensu lato based on molecular and morphological data.
Scientific reports, 2021Co-Authors: Yevhen Maltsev, John Patrick Kociolek, Svetlana Maltseva, Regine Jahn, Maxim KulikovskiyAbstract:Until now, the reported diversity of representatives from the genus Hantzschia inhabiting soils from different parts of Eurasia was limited to the few species H. amphioxys, H. elongata and H. vivax and some of their infraspecific taxa. We have studied the morphology, ultrastructure and phylogeny of 25 soil diatom strains, which according to published description would be assigned to “H. amphioxys sensu lato” using 18S rDNA, 28S rDNA and rbcL. We show that strains are made up of seven different species of Hantzschia, including five new for science. Five strains were identified as H. abundans. This species has a slight curvature of the raphe near its external proximal ends. Four of the examined strains were represented by different populations of H. amphioxys and their morphological characteristics fully correspond with its isolectotype and epitype. The main specific features of this species include 21–25 striae in 10 μm, 6–11 fibulae in 10 μm, 40–50 areolae in 10 μm and internal proximal raphe endings bent in opposite directions. H. attractiva sp. nov., H. belgica sp. nov., H. parva sp. nov., H. pseudomongolica sp. nov. and H. stepposa sp. nov. were described based on differences in the shape of the valves, significant differences in dimensions, a lower number of striae and areolae in 10 μm and the degree and direction of deflection of the internal central raphe endings. Based on the study of the morphological variability and phylogeny of soil Hantzschia-species from different geographical locations we conclude that while some species such as H. amphioxys are truly cosmopolitan in their distributions, some sympatric populations of pseudocryptic taxa exist in the Holarctic.
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Species composition and distribution of centric diatoms from Türkmen Mountain (Sakarya River Basin/Turkey)
Turkish Journal of Botany, 2013Co-Authors: Cüneyd Nadir Solak, Maxim KulikovskiyAbstract:Diatoms are used for monitoring the environmental conditions of water. We have little information about centric diatoms in Turkish freshwaters. A total of 50 samples were collected from some springs and small streams of Turkmen Mountain. As a result, 7 species [Cyclotella meneghiniana Kutzing, C. ocellata Pantocsek, Cyclostephanos dubius (Fricke) Round, Handmannia balatonis (Pantocsek) Kulikovskiy & Solak comb. nov., Melosira varians Agardh, Stephanodiscus hantzschii Grunow, and S. minutulus (Kutzing) Cleve & Moller] were identified, and we also suggest in this study that a new combination for Cyclotella balatonis Pantocsek should be Handmannia balatonis comb. nov. and for C. praetermissa Lund should be Handmannia praetermissa comb. nov.
Rafael Carballeira - One of the best experts on this subject based on the ideXlab platform.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
2019Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschia as an independent genus. It is concluded that, while a core of hantzschioid species may exist that can be classified together, corresponding to the traditional understanding of the genus Hantzschia, there is no single morphological feature common to all of them that can be used to diagnose the group and differentiate it from the various hantzschioid lineages that are separate from true Hantzschia and currently placed in e.g. Nitzschia or Cymbellonitzschia. Testing whether a hantzschioid species does or does not belong to Hantzschia will in many cases require molecular evidence. Although the new coastal species does not belong to the same lineage as the type species of Nitzschia, N. sigmoidea, it is described for the moment as N. varelae Carballeira, D.G. Mann & Trobajo, sp. nov., until there is a better understanding of generic limits in the Bacillariaceae following a wider molecular and morphological survey of that family.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
European Journal of Phycology, 2017Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:AbstractA previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschi...
Shinya Sato - One of the best experts on this subject based on the ideXlab platform.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
2019Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschia as an independent genus. It is concluded that, while a core of hantzschioid species may exist that can be classified together, corresponding to the traditional understanding of the genus Hantzschia, there is no single morphological feature common to all of them that can be used to diagnose the group and differentiate it from the various hantzschioid lineages that are separate from true Hantzschia and currently placed in e.g. Nitzschia or Cymbellonitzschia. Testing whether a hantzschioid species does or does not belong to Hantzschia will in many cases require molecular evidence. Although the new coastal species does not belong to the same lineage as the type species of Nitzschia, N. sigmoidea, it is described for the moment as N. varelae Carballeira, D.G. Mann & Trobajo, sp. nov., until there is a better understanding of generic limits in the Bacillariaceae following a wider molecular and morphological survey of that family.
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A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae
European Journal of Phycology, 2017Co-Authors: Rafael Carballeira, Rosa Trobajo, Manel Leira, Xavier Benito, Shinya Sato, David G. MannAbstract:AbstractA previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschi...
