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Luc Ector - One of the best experts on this subject based on the ideXlab platform.
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Achnanthidium neotropicum sp nov a new freshwater diatom from lake apastepeque in el salvador central america
Phytotaxa, 2018Co-Authors: Kim J Krahn, Luc Ector, Carlos E Wetzel, Antje SchwalbAbstract:A new freshwater diatom recovered from modern and subfossil sediments of Lake Apastepeque in El Salvador, Achnanthidium neotropicum sp. nov. , is described based on light and scanning electron microscopy observations. The species is characterized by valves with linear, sometimes centrally constricted (mainly in large cells), outlines, broadly rounded to subrostrate apices, and often rectangular fascia. Striae are composed of 3–4 rounded to slit-like areolae. It can be separated from similar species by valve outline, together with striae density, and number of areolae per stria. Based on the straight distal raphe endings this species can be assigned to the A. minutissimum complex. The new species is compared to morphologically resembling species from the genus Achnanthidium Kutzing.
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analysis of the type material of planothidium delicatulum bacillariophyta with the description of two new planothidium species from the sub antarctic region
Fottea, 2018Co-Authors: Bart Van De Vijver, Carlos E Wetzel, Luc EctorAbstract:During a survey of the freshwater diatom flora on the sub-Antarctic islands of the southern Indian Ocean, two new Planothidium species were observed, showing some resemblance to Planothidium delicatulum. Therefore, the type material of Achnanthidium delicatulum Kutzing was analysed, a common species in northern hemisphere waterbodies that was later transferred to the genus Planothidium. Additionally the material of Types du Synopsis des Diatomees de Belgique n° 234, designated in 1980 as neotype for Achnanthes delicatula was investigated. This analysis showed that the population in Types n° 234 is not conspecific with Achnanthidium delicatulum but in fact is a population of Planothidium galaicum. Both Planothidium species in the investigated Antarctic material are described as new to science: P. lilianeanum Van de Vijver sp. nov. and P. australodelicatulum Van de Vijver, C.E.Wetzel et Ector sp. nov. The new species can be differentiated based on differences in valve outline, presence of ridges and silica outgrowths on the rapheless valve, the structure of the raphe and the shape and size of the central area. Notes on the ecology and distribution of the new Antarctic species are added. Achnanthidium delicatulum is formally lectotypified.
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type analysis of Achnanthidium minutissimum and a catenatum and description of a tropicocatenatum sp nov bacillariophyta a common species in brazilian reservoirs
Plant Ecology and Evolution, 2017Co-Authors: Gisele Carolina Marquardt, Carlos E Wetzel, Saul Blanco, Livia F Costa, Denise C Bicudo, Carlos Eduardo De Mattos Bicudo, Luc EctorAbstract:Background and aims A commonly occurring Achnanthidium species has been observed in Brazilian reservoirs. The morphological features were described based on light and scanning electron microscope obs
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morphological variability within the Achnanthidium minutissimum species complex bacillariophyta comparison between the type material of achnanthes minutissima and related taxa and new freshwater Achnanthidium species from portugal
Phytotaxa, 2015Co-Authors: Maria Helena Novais, Ingrid Jüttner, Maria Manuela Morais, Lucien Hoffmann, Luc EctorAbstract:Two new taxa similar to Achnanthidium minutissimum were common and abundant in samples collected during a survey of benthic diatoms in watercourses from mainland Portugal. They are described here as A . duriense , sp . nov . and A . lusitanicum , sp . nov . In addition, the recently described A . pseudolineare is reported from various localities and its ecology is described in detail. The new Achnanthidium species from Portugal were compared with the type material of morphologically similar taxa: Achnanthidium microcephalum , Achnanthes minutissima , A . minutissima var. cryptocephala , A . minutissima var. inconspicua and A . nana . The analysis of this type material confirmed that Achnanthes minutissima var. cryptocephala should be regarded as a different taxon, and a new combination is proposed, Achnanthidium neocryptocephalum , stat., comb. et nom . nov . Achnanthes minutissima var. inconspicua is now considered as a younger synonym of Achnanthidium lineare . Based on a detailed morphological study of specimens of Achnanthes nana from Scotland, Nepal and Portugal, this taxon is transferred to the genus Achnanthidium as Achnanthidium nanum , comb . nov .
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analysis of the type material of Achnanthidium lanceolatum brebisson ex kutzing bacillariophyta with the description of two new planothidium species from the antarctic region
Fottea, 2013Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, Carlos E Wetzel, Luc EctorAbstract:The type material of Achnanthidium lanceolatum (transferred in 1999 to the genus Planothidium) is investigated to reveal the identity of several Planothidium populations from the Antarctic Region. The morphology and the ultrastructure was analysed using light and scanning electron microscopy. The results of this analysis revealed the presence of two so far undescribed Planothidium species in the investigated Antarctic material. Both species are described as new to science: P. rost- rolanceolatum Van de VijVer, KopaloVa et zidaroVa sp. nov. and P. subantarcticum Van de VijVer et c.e.Wetzel sp. nov. The new species can be differentiated based on differences in valve outline and the shape and size of the central area. Planothidium lanceolatum is formally lectotypified. Notes on the ecology and distribution of the new Antarctic species are added.
Paul B Hamilton - One of the best experts on this subject based on the ideXlab platform.
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Molecular and morphological characterization of the Achnanthidium minutissimum complex (Bacillariophyta) in Petuniabukta (Spitsbergen, High Arctic) including the description of A. digitatum sp. nov.
2019Co-Authors: Eveline Pinseel, Bart Van De Vijver, Paul B Hamilton, Pieter Vanormelingen, Wim Vyverman, Kateřina KopalováAbstract:Recent morphology-based investigations of freshwater Arctic diatoms suggest that many species remain to be discovered, reflecting a unique polar flora. During a survey of the freshwater diatom flora of northern Billefjorden, including the Petuniabukta fjord region (Spitsbergen), several morphodemes belonging to the Achnanthidium minutissimum species complex were recorded. Molecular phylogenies based on rbcL, 28S and 18S sequences, including single cells from Canada and strains from Marion Island (sub-Antarctica) and GenBank revealed the presence of 12 distinct A. minutissimum complex lineages, of which three contained strains from Spitsbergen. One Arctic lineage is described as a new species. Achnanthidium digitatum sp. nov. is morphologically characterized by narrow, linear to only slightly lanceolate valves and usually two areolae per stria. The two remaining Arctic lineages are in need of a more complete morphological and molecular comparison with other representatives of the A. minutissimum complex to clarify their taxonomic identity. It is argued that implementation of molecular data in the taxonomy of Achnanthidium will be essential to solve the taxonomic problems associated with this group, eventually resulting in a better understanding of the biogeography and niche differentiation of different species belonging to the A. minutissimum complex. Ideally, this should be based on more variable genes than the currently widely used 18S, which does not have a species level resolution in the A. minutissimum complex.
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two new species of Achnanthidium kutzing bacillariophyceae from kolli hills eastern ghats india
Fottea, 2017Co-Authors: Karthick Balasubramanian, Jonathan C Taylor, Paul B HamiltonAbstract:Two new freshwater species of Achnanthidium Kutzing are described from Eastern Ghats Mountain range of Peninsular India based on light and scanning electron microscopy observations. Achnanthidium initium sp. nov. belongs to the group of Achnanthidium taxa that have terminal raphe fissures curved to opposite sides of the valve. This taxon is characterized by distinctive fascia, raphe endings extending to the valve margin, lineate distal raphe endings and 2-5 linear areola per striae. Achnanthidium linannulum sp. nov. belongs to the group of Achnanthidium taxa with terminal raphe fissures curved to the same side of the valve. This species is characterized by the presence of occluded areolae near the margin, striae orientation and the weakly bent internal distal ends of the raphe. These new species are known only from their type locality, oligotrophic Masilla Waterfalls from Kolli Hills, Eastern Ghats.
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morphological and ecological variation within the Achnanthidium minutissimum bacillariophyceae species complex1
Journal of Phycology, 2007Co-Authors: Marina Potapova, Paul B HamiltonAbstract:Variation of frustular morphology within the Achnanthidium minutissimum (Kutz.) Czarn. species complex was studied in type populations of 12 described taxa and in 30 recent North American river samples. The SEM observations in this study and other publications showed that ultrastructural char- acters on their own do not discriminate among taxa within the A. minutissimum complex. Therefore, an attempt was made to use other characters, such as valve shape and striation pattern, to delineate mor- phological groups. The sliding-landmarks method was used to obtain valve-shape descriptors. These shape variables were combined with conventional morphological characters in multivariate analyses. It was shown that some historically recognized taxa are morphologically distinct, while others are difficult to differentiate. Morphological grouping of ''old'' taxa most similar to A. minutissimum did not correspond to their taxonomic hierarchy in contemporary diatom floras. Morphometric analysis of a data set of 728 specimens from North American rivers revealed six morphological groups, although it was impossible to draw clear boundaries among them. These morpholo- gical groups differed significantly in their ecological characteristics and could be recommended as indica- tors of water quality. Application of the discriminant function analysis based on shape variables and stria- tion pattern showed that North American specimens could be more consistently classified into the six groups identified in our analysis than into historically recognized taxa.
Karthick Balasubramanian - One of the best experts on this subject based on the ideXlab platform.
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two new species of Achnanthidium kutzing bacillariophyceae from kolli hills eastern ghats india
Fottea, 2017Co-Authors: Karthick Balasubramanian, Jonathan C Taylor, Paul B HamiltonAbstract:Two new freshwater species of Achnanthidium Kutzing are described from Eastern Ghats Mountain range of Peninsular India based on light and scanning electron microscopy observations. Achnanthidium initium sp. nov. belongs to the group of Achnanthidium taxa that have terminal raphe fissures curved to opposite sides of the valve. This taxon is characterized by distinctive fascia, raphe endings extending to the valve margin, lineate distal raphe endings and 2-5 linear areola per striae. Achnanthidium linannulum sp. nov. belongs to the group of Achnanthidium taxa with terminal raphe fissures curved to the same side of the valve. This species is characterized by the presence of occluded areolae near the margin, striae orientation and the weakly bent internal distal ends of the raphe. These new species are known only from their type locality, oligotrophic Masilla Waterfalls from Kolli Hills, Eastern Ghats.
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Two new species of Achnanthidium Kützing (Bacillariophyceae) from Kolli Hills, Eastern Ghats, India
Fottea, 2017Co-Authors: Karthick Balasubramanian, Taylor, Jonathan C., Hamilton, Paul B.Abstract:Two new freshwater species of Achnanthidium Kützing are described from Eastern Ghats Mountain range of Peninsular India based on light and scanning electron microscopy observations. Achnanthidium initium sp. nov. belongs to the group of Achnanthidium taxa that have terminal raphe fissures curved to opposite sides of the valve. This taxon is characterized by distinctive fascia, raphe endings extending to the valve margin, lineate distal raphe endings and 2–5 linear areola per striae. Achnanthidium linannulum sp. nov. belongs to the group of Achnanthidium taxa with terminal raphe fissures curved to the same side of the valve. This species is characterized by the presence of occluded areolae near the margin, striae orientation and the weakly bent internal distal ends of the raphe. These new species are known only from their type locality, oligotrophic Masilla Waterfalls from Kolli Hills, Eastern Ghats.South African National Research Foundation (NRF
Horst Langebertalot - One of the best experts on this subject based on the ideXlab platform.
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four new european Achnanthidium species bacillariophyceae
Algological Studies, 2011Co-Authors: Bart Van De Vijver, Horst Langebertalot, Amelie Jarlman, Adrienne Mertens, Myriam De Haan, Luc EctorAbstract:Four new Achnanthidium species belonging to the species complex around A. minutissimum (Kutz.) Czarn. are described from different localities in Europe. Achnanthidium hoffmannii Van de VijVer, eCtor, a. Mertens et jarlMan nov. spec. was found in several oligotrophic, circumneutral rivers in Sweden. The species is characterized by the presence of irregular, slit-like areolae near the valve margin, clearly visible in LM. Achnanthidium acerosum Van de VijVer, lange-Bert. et jarlMan nov. spec., a narrow, linearlanceolate species with protracted, narrowly capitate apices, is likewise described from Sweden, but only found in one oligotrophic river in southern Sweden. Achnanthidium ertzii Van de VijVer et lange-Bert. nov. spec. was observed in a moss vegetation in a Laurisilva forest on the Portuguese island of Madeira. The species has an elongate, linear-elliptical valve outline with clearly capitate apices. The last species, A. tepidaricola Van de VijVer et M. de Haan nov. spec., found in a greenhouse of the National Botanic Garden of Belgium, has almost parallel margins and broadly rounded, protracted, capitate apices. All four species are sufficiently different from similar existing species.
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Achnanthidium chitrakootense spec nov from rivers of northern and central india
Polish Botanical Journal, 2010Co-Authors: Agata Z Wojtal, Horst Langebertalot, Rachna Nautiyal, W Szafer, J W Goetheuniversity, Jyoti Verma, Prakash NautiyalAbstract:The group of diatoms morphologically similar to Achnanthidium pyrenaicum (Hustedt) Kobayasi includes a number of ecologically important taxa. The restricted distribution patterns of some Achnanthidium Kutzing species have become more obvious after detailed studies of this relatively small group. It has been characterized as having terminal raphe fi ssures curved to the same side, slit-like external areola openings, and internal hymenate areola occlusions. Unlike the rest of Achnanthidium, the new species A. chitrakootense possesses areola occlusions of an unusual type. It is also characterized by a raphe with ter- minals externally curved towards the same side of the valve, crossing the hyaline rim between the valve face and valve mantle, and internally undulate raphe terminals. The new member of the Achnanthidium pyrenaicum group is described from rivers of northern and central India. The species is documented with LM and SEM micrographs, and the frustule morphology of this species and similar taxa is compared and briefl y discussed.
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the genera Achnanthidium kutzing and psammothidium bukhtiyarova et round in the family achnanthidiaceae bacillariophyceae a reappraisal of the differential criteria
Cryptogamie Algologie, 2007Co-Authors: Olivier Monnier, Horst Langebertalot, Lucien Hoffmann, Luc EctorAbstract:Les caracteres de distinction des genres Achnanthidium et Psammothidium, ce dernier recemment separe des autres especes d'Achnanthes sensu lato, appartenant a la famille des Achnanthidiaceae D.G. Mann, ont ete evalues sur la base de l'etude morphologique de onze especes communes trouvees dans les cours d'eau du Luxembourg. A la lumiere de ces observations - completees par les donnees bibliographiques - il est conclu que ces deux genres ne peuvent etre circonscrits sans ambiguite sur la base des seuls criteres morphologiques. De plus, aucune distinction n'a pu etre validee par des etudes ontogenetiques ou phylogenetiques. En consequence, Achnanthes bioretii, A. daonensis, A. austriaca var. helvetica, A. Lauenburgiana et Navicula subatomoides ont ete transferes dans Achnanthidium.
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Achnanthidium dolomiticum sp nov bacillariophyta from oligotrophic mountain springs and lakes fed by dolomite aquifers 1
Journal of Phycology, 2006Co-Authors: Marco Cantonati, Horst LangebertalotAbstract:A new benthic freshwater diatom, Achnanthidium dolomiticum sp. nov., was identified from light and scanning electron micrographs. The most characteristic morphological features are a narrow, but distinctive fascia; a filiform raphe with narrowly spaced central ends and a very narrow and straight axial area on the raphe valve; a convex-shaped rapheless valve; the length/width ratio; and valve outline. The new species has been found so far to be mainly epiphytic on bryophytes and aquatic vascular plants in carbonate springs and lakes of the Italian Alps. The environmental preferences of the new species, as assessed by the comparative analysis of these sites, appear to be quite distinctive. These freshwater habitats are fed by drainage basins dominated by dolomite lithology with medium mineralization, are oligotrophic, and are affected by seasonal desiccation. Key index words: Achnanthidium; Achnanthidium dolomiticum; desiccation; diatoms; dolomite; epiphyton; mountain lakes; oligotrophic freshwater habitats; springs
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Achnanthidium atomoides sp nov a new diatom from the grand duchy of luxembourg
Vie et milieu, 2004Co-Authors: Olivier Monnier, Horst Langebertalot, Lucien Hoffmann, If Rimet, Luc EctorAbstract:Achnanthidium atomoides Monnier, Lange-Bertalot et Ector, une nouvelle espece de la famille des Achnanthidiaceae D.G. Mann vivant dans certaines rivieres du Grand-Duche du Luxembourg, est decrite en microscopie optique et electronique a balayage. Sa distribution et son ecologie sont precisees. Elle est comparee a l'espece tres proche Achnanthes atomus Hustedt, recombinee dans le genre Achnanthidium Kutzing comme Achnanthidium atomus (Hustedt) Monnier, Lange-Bertalot et Ector.
Bart Van De Vijver - One of the best experts on this subject based on the ideXlab platform.
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Molecular and morphological characterization of the Achnanthidium minutissimum complex (Bacillariophyta) in Petuniabukta (Spitsbergen, High Arctic) including the description of A. digitatum sp. nov.
2019Co-Authors: Eveline Pinseel, Bart Van De Vijver, Paul B Hamilton, Pieter Vanormelingen, Wim Vyverman, Kateřina KopalováAbstract:Recent morphology-based investigations of freshwater Arctic diatoms suggest that many species remain to be discovered, reflecting a unique polar flora. During a survey of the freshwater diatom flora of northern Billefjorden, including the Petuniabukta fjord region (Spitsbergen), several morphodemes belonging to the Achnanthidium minutissimum species complex were recorded. Molecular phylogenies based on rbcL, 28S and 18S sequences, including single cells from Canada and strains from Marion Island (sub-Antarctica) and GenBank revealed the presence of 12 distinct A. minutissimum complex lineages, of which three contained strains from Spitsbergen. One Arctic lineage is described as a new species. Achnanthidium digitatum sp. nov. is morphologically characterized by narrow, linear to only slightly lanceolate valves and usually two areolae per stria. The two remaining Arctic lineages are in need of a more complete morphological and molecular comparison with other representatives of the A. minutissimum complex to clarify their taxonomic identity. It is argued that implementation of molecular data in the taxonomy of Achnanthidium will be essential to solve the taxonomic problems associated with this group, eventually resulting in a better understanding of the biogeography and niche differentiation of different species belonging to the A. minutissimum complex. Ideally, this should be based on more variable genes than the currently widely used 18S, which does not have a species level resolution in the A. minutissimum complex.
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analysis of the type material of planothidium delicatulum bacillariophyta with the description of two new planothidium species from the sub antarctic region
Fottea, 2018Co-Authors: Bart Van De Vijver, Carlos E Wetzel, Luc EctorAbstract:During a survey of the freshwater diatom flora on the sub-Antarctic islands of the southern Indian Ocean, two new Planothidium species were observed, showing some resemblance to Planothidium delicatulum. Therefore, the type material of Achnanthidium delicatulum Kutzing was analysed, a common species in northern hemisphere waterbodies that was later transferred to the genus Planothidium. Additionally the material of Types du Synopsis des Diatomees de Belgique n° 234, designated in 1980 as neotype for Achnanthes delicatula was investigated. This analysis showed that the population in Types n° 234 is not conspecific with Achnanthidium delicatulum but in fact is a population of Planothidium galaicum. Both Planothidium species in the investigated Antarctic material are described as new to science: P. lilianeanum Van de Vijver sp. nov. and P. australodelicatulum Van de Vijver, C.E.Wetzel et Ector sp. nov. The new species can be differentiated based on differences in valve outline, presence of ridges and silica outgrowths on the rapheless valve, the structure of the raphe and the shape and size of the central area. Notes on the ecology and distribution of the new Antarctic species are added. Achnanthidium delicatulum is formally lectotypified.
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Achnanthidium petuniabuktianum sp. nov. (Achnanthidiaceae, Bacillariophyta), a new representative of the A . pyrenaicum group from Spitsbergen (Svalbard Archipelago, High Arctic)
Phytotaxa, 2015Co-Authors: Eveline Pinseel, Bart Van De Vijver, Kateřina KopalováAbstract:During a survey of the freshwater littoral diatom flora from lakes and ponds in the region of Petuniabukta on Spitsbergen (Svalbard Archipelago, High Arctic region), a new Achnanthidium species, A . petuniabuktianum sp. nov., has been recorded. Achnanthidium petuniabuktianum is a new representative of the A . pyrenaicum group as evidenced by its curved distal raphe fissures. The present paper describes in detail the morphology of A . petuniabuktianum based on light and scanning electron microscopy. The new taxon is characterized in having linear valves with parallel margins and broadly rounded, never protracted apices and a characteristic—in light microscopy hardly discernible—striation pattern consisting of very short striae composed of one or two small, always slit-like areolae. Based on current results, Achnanthidium petuniabuktianum is a benthic taxon occurring in epilithic and epiphytic habitats in the littoral zones of freshwater lakes and ponds.
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four Achnanthidium species bacillariophyta formerly identifi ed as Achnanthidium minutissimum from the antarctic region
European journal of taxonomy, 2014Co-Authors: Bart Van De VijverAbstract:Four taxa belonging to the complex of species around Achnanthidium minutissimum were found during the ongoing taxonomic revision of the Antarctic freshwater and limno-terrestrial diatom fl ora. Two taxa were previously described as Achnanthidium lailae and A. sieminskae. Two others were formerly identifi ed as A. minutissimum but detailed light and scanning electron microscopical observations revealed suffi cient morphological differences compared to the type of A. minutissimum, to justify their separation and description as new taxa: Achnanthidium indistinctum and A. maritimo-antarcticum. The morphology and ecology of all four taxa are discussed comparing the species with morphologically similar taxa. The biogeographical consequences of the splitting of the former A. minutissimum complex in the Antarctic Region are discussed.
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analysis of the type material of Achnanthidium lanceolatum brebisson ex kutzing bacillariophyta with the description of two new planothidium species from the antarctic region
Fottea, 2013Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, Carlos E Wetzel, Luc EctorAbstract:The type material of Achnanthidium lanceolatum (transferred in 1999 to the genus Planothidium) is investigated to reveal the identity of several Planothidium populations from the Antarctic Region. The morphology and the ultrastructure was analysed using light and scanning electron microscopy. The results of this analysis revealed the presence of two so far undescribed Planothidium species in the investigated Antarctic material. Both species are described as new to science: P. rost- rolanceolatum Van de VijVer, KopaloVa et zidaroVa sp. nov. and P. subantarcticum Van de VijVer et c.e.Wetzel sp. nov. The new species can be differentiated based on differences in valve outline and the shape and size of the central area. Planothidium lanceolatum is formally lectotypified. Notes on the ecology and distribution of the new Antarctic species are added.