Bart Van de Vijver

Meise Botanic Garden · Research Department

During the analysis of a voucher sample from Frahan (Belgium) collected by the Belgian diatomist Charles-Henri Delogne, seven species from the genus Humidophila (Bacillariophyta) have been observed. Two species could not be identified using the currently available literature and are described as new to science. Humidophila delognei sp. nov. has alw...

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....

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...

There is growing consensus that we have entered the Anthropocene, a new geological epoch during which human activity has altered the global environment and climate system profoundly. The Arctic is particularly sensitive to climate change and warms up 2-3 times faster compared to the global mean, mostly due to positive feedback mechanisms between oc...

Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. The latest observations indicate that epibiotic diatom communities constitute diverse, polyphyletic, and compositionally stable assemblages that include both putatively obligate epizoic and...

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...

Background Ice-free areas in the Antarctic region are strongly limited. The presence of marine mammals and birds in those areas influence soil properties and vegetation composition. Studies on the terrestrial diatom flora in soils influenced by sea birds in the Maritime Antarctic region are scarce. Methods Samples were collected from two transects...

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...

Diatoms constitute an important and diverse component of terrestrial protist communities but remain poorly studied, especially in the Antarctic realm. Here, we investigated the diversity and community structure of the terrestrial diatom flora from the Ulu Peninsula, James Ross Island (Maritime Antarctic Region) using a morphology-based dataset and...

Supplementary Information (listing of Albert Grunow's (1826 - 1914) publications with links to online sources).

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...

The past two decades, the non-marine diatom flora in the sub-Aantarctic region has been intensively revised. Historic collections provide excellent tools for answering taxonomic, community-related, and biogeographical questions. This study analysed the moss-inhabiting diatom flora from sub-Antarctic Campbell Island in samples collected in 1969–1970...

A new species of araphid diatoms with bilobate ends is described as Staurosirella tigris sp. nov. It was found in mid Miocene glacial-lacustrine sediments in the Friis Hills, Antarctica. The new diatom is placed in Staurosirella because it has striae composed of apically-oriented lineolae, separated by long, thin vimines, and it lacks rimoportulae....

A new species of araphid diatoms with bilobate ends is described as Staurosirella tigris sp. nov. It was found in mid-Miocene glacial-lacustrine sediments in the Friis Hills, Antarctica. The new diatom is placed in Staurosirella because it has striae composed of apically-oriented lineolae, separated by long, thin vimines, and it lacks rimoportulae....

In 1856, the Reverend William Smith (1808–1857) described four new Odontidium species in the second volume of his “A synopsis of the British Diatomaceae” (Smith 1856). Smith observed the new species in several samples and listed all localities for each species. The original collection of the British Diatomaceae, containing almost all samples used t...

Analysis of type material of Opephora pacifica and emendation of the genus Opephora (Bacillariophyta) Abstract: 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,...

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...

Synedra planktonica was originally described by Hains and Sebring from a freshwater locality in the southeastern USA using light and transmission electron microscopy. The authors placed S. planktonica into the genus Synedra Ehrenberg because of its solitary habit and lack of marginal linking spines. Since the original description of S. planktonica,...

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...

Background: Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. Recent activity describing the epizoic diatoms growing on marine vertebrates suggests that these epibiotic diatom communities constitute diverse, polyphyletic, and compositionall...

Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. Recent activity describing epizoic diatoms suggests that epibiotic diatom communities constitute diverse, polyphyletic, and compositionally stable assemblages that include both putatively ob...

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...

Chrysophyte algae live predominantly in freshwater habitats, therefore marine chryso-phyte stomatocysts are less common and poorly documented. Here we report on the occurrence of two unknown chrysophycean stomatocysts in a complex epizoic biofilm formed on a carapace of a loggerhead sea turtle (Caretta caretta) found injured on the southeastern coa...

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...

Hyalosira gene sequences are divided into two clades within different families. We examined authentic material of Hyalosira (isotype material of H. obtusangula, synonymous with H. delicatula) and voucher specimens of published sequences, and pooled our observations of Hyalosira-like taxa from benthic and epizoic habitats in several parts of the glo...

Background and aims – Despite the ongoing taxonomical revision of the entire (sub)-Antarctic diatom flora, our knowledge on the ecology and community associations of moss-inhabiting diatoms is still rather limited. In the present study, our research aim was to survey the diversity together with the environmental factors structuring the epiphytic mo...

Terrestrial biota in the Antarctic are more globally distinct and highly structured biogeographically than previously believed, but information on biogeographic patterns and endemism in freshwater communities is largely lacking. We studied biogeographic patterns of Antarctic freshwater diatoms based on the analysis of species occurrences in a datas...

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...

Like aquatic diatoms, terrestrial diatoms are sensitive to multiple environmental factors such as pH, anthropic disturbances, soil moisture and nitrogen. While most aquatic diatom species have well-known autecological values for several important variables, qualifying them as biological indicators, this potential has not yet been untapped for terre...

During a study of the limno-terrestrial diatoms on King George Island (South Shetland Islands), an unknown Navicula taxon was observed. Detailed morphological analysis based on both light and scanning electron microscopy observations revealed a unique set of morphological features, that were not observed in any Navicula taxon known so far. Despite...

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...

The current study focuses on four species from the primarily marine diatom genus Craspedostauros that were observed growing attached to numerous sea turtles and sea turtle-associated barnacles from Croatia and South Africa. Three of the examined taxa, C. danayanus sp. nov., C. legouvelloanus sp. nov., and C. macewanii sp. nov. are described based o...

In recent years, biofilm-forming diatoms have received increased attention as sea turtle epibionts. However, most of the research has focused on carapace-associated taxa and communities, while less is known about diatoms growing on sea turtle skin. The current study investigated diatom diversity on the skin of loggerhead sea turtle heads detached f...

The non-marine diatom flora of the Antarctic continent is currently being revised as recent work within the Maritime and Sub-Antarctic regions has unveiled a number of new endemic species. The under reporting of endemic species is partially due to the historic ‘force-fitting’ of Antarctic species into European names. Within East Antarctica, the Ves...

During a survey of the moss-inhabiting diatom flora of the sub-Antarctic Campbell Island, located in the southern Pacific Ocean, several unknown centric diatoms were observed that could not be identified using the currently available literature. Detailed light and scanning electron microscopical observations and comparisons with the characters of s...

Epizoic diatoms form an important part of micro-epibiota of marine vertebrates such as whales and sea turtles. The present study explores and compares the diversity and biogeography of diatom communities growing on the skin and shell of loggerhead sea turtles (Caretta caretta) from four different localities: Adriatic Sea (Croatia), Ionian Sea (Gree...

During a survey of the terrestrial diatom flora of the Maritime Antarctic Region, an unknown Luticola taxon that could not be identified using the currently available literature was observed on two islands of the South Shetland Archipelago. After a detailed morphological analysis and comparison, the unknown taxon is described as Luticola puchalskia...

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...

Soil micro-organisms drive the global carbon and nutrient cycles that underlie essential ecosystem functions. Yet, we are only beginning to grasp the drivers of terrestrial microbial diversity and biogeography, which presents a substantial barrier to understanding community dynamics and ecosystem functioning. This is especially true for soil protis...

Diatoms are useful ecological and paleolimnological indicators routinely used to reconstruct past conditions and monitor environmental change. Despite this, diatom assemblages from lake sediment cores are often difficult to interpret due to a limited knowledge of the ecology of some species, some of which may originate from the adjacent limno-terre...

The French part of the Rhin-Meuse basin is quite heterogeneous due to the broad variability in pH and conductivity ranges of its rivers and streams. Parts of the basin are characterized by the presence of typical natural or anthropogenically induced brackish environments, showing a typical diatom flora. Since many brackish diatom species observed i...

A novel diatom species belonging to the genus Nagumoea is described based on detailed light and scanning electron microscopy observations. The new taxon was found abundantly in several samples collected from seagrass on the southernmost coasts of Mozambique, Southern Africa. While the new species shows characters (e.g. scalariform valvocopula, fibu...

Benthic diatoms are widely used as bio-indicators in water quality monitoring of rivers and streams, but less commonly in lentic waterbodies such as pools and lakes. Currently, a new method for assessing the ecological status of lakes is being tested in France to meet the requirements of the European Water Framework Directive (WFD) 2000/60/EC. This...

During a survey of the freshwater diatom flora of the sub-Antarctic Campbell Island, located in the southern Pacific Ocean, an unknown freshwater diatom was observed forming long colonies using linking spines. Detailed morphological analysis based on light and scanning electron microscopical observations and comparison with all known Frankophila ta...

To understand the complexity of the climate patterns in the Holocene, it is necessary to build detailed chronologies that provide a holistic picture of the individual climate periods occurring in the polar regions. In this regard, here we present a completely new, 14C-dated and synchronised multi-proxy chronology from the Lake Anónima (Vega Island,...

During a survey of the epizoic diatom flora on carapaces of loggerhead sea turtles (Caretta caretta) from the Adriatic Sea, a fairly large population of an unknown marine Planothidium species was observed. Detailed morphological analysis based on scanning electron microscopy observations and comparison with a large number of known Planothidium spec...

Background and aims – During a survey of the soil diatom flora of the sub-Antarctic islands in the southern Indian Ocean, an unknown small-celled naviculoid taxon was discovered living in small cracks in cliffs bordering the ocean. The taxon showed a set of morphological features only found in the genus Microcostatus. However, the unknown taxon cou...