Luc Ector

Luxembourg Institute of Science and Technology (LIST) | LIST · Department of Environment and Agro-Biotechnologies (EVA)

Springs are unique aquatic environments that signifcantly contribute to regional and global biodiversity but are also susceptible to disturbances because of their small size. Mediterranean thermal springs remain poorly studied, and little is known about how different environmental and disturbance factors affect their aquatic communities. In this st...

Fragilaria vaucheriae is one of the most common Fragilaria 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....

The historic type material of Microneis gracillima, Navicula pyrenaica, Achnanthes amphicephala, Achnanthes thienemannii and Achnanthidium rostropyrenaicum was investigated together with additional European populations of these species using light and scanning electron microscopy. The morphology of the species was compared to similar taxa. Achnanth...

Little is still known about the low dose effects of radiation on the microbial communities in the environment. Mineral springs are ecosystems than can be affected by natural radioactivity. These extreme environments are, therefore, observatories for studying the influence of chronic radioactivity on the natural biota. In these ecosystems we find di...

The present study aims to expand the knowledge on Achnanthidium species occurring in tropical areas of southern Brazil. For this purpose, 345 samples from 179 sampling sites distributed throughout the state of São Paulo were analyzed for ‘monoraphid’ diatom diversity. This paper focuses on samples with a high abundance of Achnanthidium species. The...

Six species of the genus Achnanthidium Ktz. with straight terminal raphe fissures including Achnanthidium caledonicum (Lange-Bert.) Lange-Bert., A. sieminskae Witkowski, Kulikowskiy & Riaux-Gob., Achnanthidium neomicrocephalum Lange-Bert. & F.Staab and Achnanthidium minutissimum (Ktz.) Czarn. were studied using light and scanning electron microscop...

Fragilaria gracilis is one of the most reported Fragilaria species in Europe, observed in a broad range of water bodies, ranging from (ultra)oligotrophic rivers to even eutrophic lakes. A revision of this important taxon based on the analysis of the morphology of a large number of historic and recent populations was highly needed. In the present st...

A new species of araphid diatom is described from a temporary stream in southern Portugal, Fragilaria odeloucaensis sp. nov., which belongs to the group of Fragilaria with widely linear to lanceolate valve outline, spaced striae, lacking spines, and with well-developed apical pore fields. The new taxon can be distinguished based on five unique feat...

La source de la Poix est une particularité géologique du Massif central français car elle est connue pour être bitumineuse associée à de l’eau salée, du méthane et des traces d’hydrogène sulfuré. Entre mars 2017 et juin 2020, trois prélèvements ont été effectués en raclant les diatomées sur la couche de bitume. De plus, les conditions physiques et...

For a long time, the identity of Staurosirella lapponica, originally described as Fragilarialapponica, was unclear as the original type material was never analysed in detail. Analysis of one of the samples used by Grunow to illustrate F. lapponica was investigated here by means of light and scanning electron microscopy. The observations allowed for...

Two morphologically similar populations of Didymosphenia were reported from the West Branch of the Farmington River, Connecticut, USA in 2014 and 2016. We described one of them as a new species, D. hullii. The other was observed subsequently in late 2016 and resembled D. geminata, but given the worldwide nuisance characteristic of this species, the...

Eunotia paludosa is an abundant and frequent diatom species in ombrotrophic, Sphagnum-dominated bog ponds in Europe. Analysis of the type material from Mandling, Austria, revealed that our currently accepted concept of E. paludosa, based on morphology, was incorrect. The valves in the type population of E. paludosa possess distinct, relatively larg...

Light and scanning electron microscope observations on the genus Fontina gen. nov. from a thermo-mineral spring of the Massif Central (France) are presented. Based on morphology, the new genus shows features that have not been described previously, such as the stria pattern, interrupted at the valve face/mantle junction and composed of one long, sl...

In the present study, a new species, Nitzschia haloserbica Vidakovi, Ector, C.E.Wetzel & Krizmani, sp. nov., is described from alkaline saline ponds and channels from Vojvodina Province (Serbia). In 2019 the new species was found in four saline ponds: Bela Bara, oka Kopovo, Velika Rusanda and Slatina. The same species was recorded four years ago in...

A new Gomphosphenia species (Bacillariophyceae) was found during a diatom survey in the “Réserve Naturelle Nationale de la Vallée de Chaudefour” (RNN VC), in the Massif Central (France). Gomphosphenia vallei sp. nov. is described from stone surfaces in Pérouse Stream, Auvergne, France. A detailed description of morphology of G. vallei is presented,...

The former Synedra rumpens complex has long puzzled diatom taxonomists. In the nineteenth century, many infraspecific taxa were described as varieties or forms of S. rumpens. In the present study, type material of Synedra rumpens and several infraspecific taxa such as S. rumpens var. fragilarioides and S. familiaris f. parva and f. major was invest...

We investigated several common, needle-shaped diatoms to better characterize the taxonomy of the genus Fragilaria in the Laurentian Great Lakes. We conducted diatom morphometric analysis facilitated by SEM and LM imaging on samples collected as a part of the USEPA’s long-term biological monitoring program. We resolved several decades-long taxonomic...

During a survey done on the mineral springs in the French Massif Central region, a new Chamaepinnularia species (Bacillariophyceae) was found and is hereby described: Chamaepinnularia salina Beauger, C.E.Wetzel, Allain & Ector sp. nov. This new small species, with valves linear with almost parallel margins, is formally described using light and sca...

Diatoms colonised most aquatic ecosystems on earth from marine to freshwater ones, and also the springs containing a fairly large and poorly known diversity of diatoms. While investigations on the influence of substrates on diatom assemblages in rivers are relatively well documented, few studies have been done for mineral springs. The purpose of th...

Several species currently belonging to the genus Fragilariforma D.M. WilliAms et round are known worldwide. This genus is mainly characterized by regular spacing of the uniseriate striae composed of round areolae bearing simple vela, and simple apical pore fields. A large number of species has been recognised for some regions of South America and t...

"Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales described a new species found in material of Maar Magallanes, Patagonia, Argentina and other lakes in southern Patagonia. This new species was analysed in detail by light and electron microscopy and a comprehensive description is given in Garcia et al. (2017: 107, 114, figs 2-45). Howeve...

Fragilaria construens var. subsalina is a common diatom found in a wide variety of aquatic systems worldwide. It was described by Hustedt (1925) from brackish waters in Oldesloe, Germany; a lectotype specimen was established by Simonsen (1987). We analysed the ultrastructure of specimens from the lectotype material by means of light (LM) and scanni...

We analysed syntype material of Odontidium harrisonii W. Smith, Odontidium mutabile W. Smith, Odontidium tabellaria W. Smith, Odontidium tabellaria var. b W. Smith, Odontidium parasiticum W. Smith, Odontidium parasiticum var. b W. Smith and Fragilaria brevistriata Grunow in Van Heurck. A combination of light and scanning electron microscopy reveale...

Fragilaria pinnata Ehrenberg is actually a member of the genus Denticula Kützing. However, due to a drift of its taxonomic concept, there is now a "floating" idea of F. pinnata as an araphid diatom associated to Staurosirella D.M.Williams & Round (as S. pinnata (Ehrenberg) D.M.Williams & Round). Upon investigation of the nomenclatural history of F....

Background and aims-As a result of the description of many new species, reanalyses of type material, and information becoming available on valve morphogenesis in small araphid diatoms lacking a rimoportulae, the existing classification scheme at the genus level needs revision. Because morphological information has increased manyfold since the syste...

The aim of this paper is to expand the current knowledge on the distribution, ecology and morphology of Pseudostaurosira cataractarum (Hustedt) C.E. Wetzel, E. Morales et Ector. We analysed several freshwater diatom assemblages within the Palearctic (Czech Republic, Eur-ope) and Neotropic ecozones (Argentina and Bolivia, South America). In all loca...

Abstract: A compilation/discussion of data published on diatoms in aquatic systems from Turkey is provided based on data ordered according to type of study, type of water body, and river basins within the conterminous Turkish territory. The majority of phycological studies in Turkey focus on phytoplankton seasonal changes in lakes and reservoirs lo...

Representatives of the Achnanthidium minutissimum (Kütz.) Czarn. complex are common and widespread diatoms in Poland. The following species were included in this study: Achnanthidium affine (Grunow) Czarn., A. caledonicum (Lange-Bert.) Lange-Bert., A. eutrophilum (Lange-Bert.) Lange-Bert., A. exile (Kütz.) Hérib., A. jackii Rabenh., A. lineare W. S...

Two new araphid diatom (Bacillariophyta) species, Pseudostaurosira oliveraiana sp. nov. and Staurosira catamarcensis sp. nov. are described from fossil material taken from the saline Laguna Colorada (Argentinian Altiplano). The morphology of the new species is studied using both light (LM) and scanning electron microscopy (SEM) and is compared to t...

Thermal springs provide natural laboratories to test the responses of biological communities to various stressors. To date, little is known about how water temperature and chemistry influence the microalgal assemblages in these ecosystems, especially in the circum-Mediterranean area. In this study, we assessed the environmental drivers of benthic d...

Based on two Andean Altiplano samples and on light and scanning electron microscopy analyses, we present six new species of “araphid” diatoms in the genus Pseudostaurosira , P. aedes sp. nov. , P. frankenae sp. nov. , P. heteropolaris sp. nov. , P. oblonga sp. nov. , P. occulta sp. nov. , and P. pulchra sp. nov. Additional data are provided for fou...

Despite evidence for microbial endemism, an understanding of the impact of geological and paleoclimate events on the evolution of regional protist communities remains elusive. Here, we provide insights into the biogeographical history of Antarctic freshwater diatoms, using lacustrine fossils from mid-Miocene and Quaternary Antarctica, and dovetail...

The diatom genus Tabellaria Ehrenberg is one of the most widely distributed genera in freshwaters, both in benthos and phytoplankton. It is rather frequent in unpolluted, circumneutral to slightly acidic and poorly mineralized lakes, streams and peat bogs. Despite being studied intensively in the last decades, the taxonomy of this genus is still un...

This third paper revising the European Brachysira species deals with Brachysira serians and the closely related B. brebissonii-intermedia complex. The morphology of these species is charac-terised in greater detail than before based on a combination of analyses of original type material and additional historic and modern samples. All taxa in this c...

The taxonomic identity of several similar Brachysira species in Europe is investigated based on a combination of the analysis of original type material, additional historic samples, and modern samples. Brachysira microcephala and B. neoexilis can be separated based on morphological and ecological differences. Brachysira microcephala shows a lanceol...

This second paper on the revision of the taxonomic identity of several Brachysira species in Europe deals with Brachysira styriaca (Grunow) R.Ross and B. zellensis (Grunow) Round & D.G. Mann. Both species were described by Grunow based on material from Lake Erlauf (Lower Austria and Styria, Austria). Analysis of type material, additional historic a...

During a biomonitoring assignment in the Swiss canton Ticino, an unknown Fragilaria taxon was discovered that could not be identified using the currently available literature. The results of a morphological comparison with the type material of F. recapitellata, based on light and scanning electron microscopy, showed that the new Swiss taxon has suf...

Periphytic diatoms growing on aquatic turtle carapaces provide an interesting example of biofouling on an animal substrate. This study dealt with the question of the specificity of epizoic diatom communities for the case of the European pond turtle (Emys orbicularis), across five water bodies in South-Eastern France; 375 diatom taxa have been ident...

Over the last years, issues concerning diatom teratological forms and environmental stress have received growing interest within the scientific community. Publications on this topic dated back to 1890 and were summarized in a review published in 2009 by the journal Hydrobiologia, accounting for high citation rates (i.e. 117 citations Scopus and 232...

Lowland intermittent ponds, although biologically important, are poorly studied water habitats. During the analyses of the material taken from lowland pond in Pelagonia Valley, and Vitachevo, Republic of North Macedonia, the diatom Sellaphora pelagonica sp. nov. was recorded and described based on light and scanning electron microscopy. The species...

Pseudostaurosira crateri sp. nov. is described from fossil material analyzed from a Quaternary sediment core retrieved from the Colônia basin (located in the Brazilian Coastal Plain, Atlantic Forest, São Paulo Metropolitan Region). Light and scanning electron microscopy revealed its morphology and enabled its comparison with morphologically similar...

A small marine monoraphid diatom with a linear-elliptic shape and simple terminal raphe endings was present on Raivavae (South Pacific). Particularly due to its different stria structure on both valves, this taxon is here classified as Cocconeis. The new species was present on the rocky intertidal shore of the coral-reef lagoon, as an epiphyte on a...

Planothidium marganaiensis sp. nov. is described from periphytic samples collected at the karst spring San Giovanni at Domusnovas, Sardinia (Italy). Light and scanning electron microscope observations revealed that the taxon shares similarities with species within the Planothidium frequentissimum sensu lato, such as P. naradoense and P. victori. Pl...

A new monoraphid diatom species appeared successively in paleolimnological records from a Quaternary sediment core (1.5±0.1 Ma) retrieved from Colônia basin (Brazilian Coastal Plain, Atlantic Forest, São Paulo Metropolitan Region), and is formally described as Planothidium scrobiculatum sp. nov. We studied the new species through light and scanning...

The genus Cocconeis is highly diverse and composed of several groups with distinctive morphologies. Several Cocconeis, characterized by complex areola occlusions, are here grouped under the new section Loculatae. The complex loculate are-olae are either present on both valves, or most often only on the sternum valve (SV). Among the Loculatae taxa,...

A new diatom species, Staurosirella paranaensis, is described only from epiphytic samples on the macrophyte Eichhornia azurea in a lake from the Upper Paraná River Floodplain in Brazil. Description of the new taxon is based on morphological characteristics observed using light and scanning electron microscopy. The new species is characterized by sh...

The genus Opephora currently contains 37 species and 27 infraspecific taxa. However, the existing literature reveals a wide morphological diversity and the need to establish defining characters to circumscribe the genus as a cohesive and, perhaps, monophyletic group. The type material of Opephora pacifica , the generitype, is analysed. We emend the...

Based on two Andean Altiplano samples and on light and scanning electron microscopy analyses, we present six new species of "araphid" diatoms in the genus Pseudostaurosira, P. aedes sp. nov., P. frankenae sp. nov., P. heteropolaris sp. nov., P. oblonga sp. nov., P. occulta sp. nov., and P. pulchra sp. nov. Additional data are provided for four othe...

A new Planothidium species was found in sediment samples (~4,000 yr BP) from the Xingu Ria (Xingu River), Brazilian Amazon. The new species morphology was analyzed using light and scanning electron microscopy. Planothidium xinguense sp. nov., is mainly characterized by its elliptical, slightly asymmetrical valves, with strongly marked short rostrat...

The type material of Synedra acus var. ostenfeldii Willi Krieg. was investigated using light and scanning electron microscopy. The species is one of the few fragilarioid taxa that forms stellate colonies. Its morphology was compared with that of Fragilaria tenera var. lemanensis Druart, Lavigne & M.Robert, another taxon forming star-shaped colonies...

During a survey of the sub-antarctic diatom flora, several populations previously identified as Fragilaria alpestris were reanalysed and compared with type material of the latter species. the morphological ultrastructure of the type of F. alpestris, the sub-antarctic populations and an additional population of F. cf. alpestris from Spitsbergen has...

Cocconeis intermedia was originally described by Peragallo & Héribaud in Héribaud (1893) as a fossil diatom species from samples collected in the Puy-de-Dôme department, Auvergne-Rhône-Alpes region (France). After the first brief description, the species was mostly mentioned as C. placentula var. intermedia in classic floristic books and, over time...

Many freshwaters in base-poor upland areas of Britain continue to be affected by acidification as a result of deposition of air pollutants, and agricultural and forestry practices. The effects of land use and annual liming on stream chemistry, diatoms and salmon populations were investigated over eight years in the upper catchment of the River Wye,...

During a revision of the genus Fragilaria in Europe, two unknown Fragilaria taxa were observed in Erken Lake, Sweden, that showed some resemblance to Fragilaria perminuta, a species described in the nineteenth century from the Great Lakes in the United States. The type material of Synedra perminuta from Lake Erie, U.S.A. (Grunow sample 2592) was an...

The aim of the present work was to present the ecological and morphological characteristics of species from the genus Achnanthes Bory sensu stricto, which develops in terrestrial mosses near the Rio de Janeiro Botanic Garden, Brazil. A literature comparison was made with other similar species, including the LM and SEM analysis of original material...

A floristic survey was performed on a temporary pond, “Laqui du Seignavoux”, situated in the Mont-Dore massif of the French Massif Central, between 2017 and 2019. Except in 2017, each year, we performed four sampling campaigns from April/May to December. Water samples and diatoms were collected. The temporary pond evolved from a poorly mineralized...

The type material of Achnanthes hauckiana Grunow has been investigated using light and scanning electron microscopy. The species, transferred to the genus Planothidium, was frequently reported from brackish and even marine environments. The original Grunow material was collected from a karstic spring near Trieste. Analysis of the material and of sa...

Gomphonema auritum A.Braun ex Kützing was originally described in 1849 in Kützing's Species Algarum (Kützing1849: 68) based on material that the latter had received from Alexander C.H. Braun (1805-1877), who collected it from the Titisee (Titi Lake) near Freiburg in southwestern Germany. The original description, "G. habitu Gomph. intricati, sed ad...

Two new diatom species are described from France. Both species have characters that allow them to be included in the genus Punctastriata D.M.Williams & Round whose main defining character is the “multiseriate striae” (i.e. presence of slender vimines and viminules). Punctastriata subalpina sp. nov. from Lake Annecy has lanceolate valve outline, wit...

The morphological diversity in the genus Surirella is summarized, a new Surirella species is described, and the valve ultrastructure of S. undulata is documented under the scanning electron microscope. The new species, Surirella dongtingensis sp. nov., has a moderately twisted frustule with open valvocopula. Under the light microscope the frustule...

The morphological diversity in the genus Surirella is summarized, a new Surirella species is described, and the valve ultrastructure of S. undulata is documented under the scanning electron microscope. The new species, Surirella dongtingensis sp. nov., has a moderately twisted frustule with open valvocopula. Under the light microscope the frustule...

The morphological diversity in the genus Surirella is summarized, a new Surirella species is described, and the valve ultrastructure of S. undulata is documented under the scanning electron microscope. The new species, Surirella dongtingensis sp. nov., has a moderately twisted frustule with open valvocopula. Under the light microscope the frustule...