Focus editorial: new contributions in diatom research

This issue contains the contributions selected from those presented at the thirty-seventh Symposium of the Association des Diatomistes de Langue française (ADLaF, Cocquyt, Ector, and Van de Vijver (2018 Cocquyt, C., L. Ector, and B. Van de Vijver. 2018. Programme Et Livre Des Résumés Du 37ème Colloque De l’Association Des Diatomistes De Langue Française (Adlaf). Meise: Jardin botanique de Meise. [Google Scholar])) held in the Meise Botanical Garden, Belgium. This French-speaking society promotes diatom research and organizes an annual symposium for facilitating the exchange of information between diatom experts. Moreover it gives young researchers the opportunity to present their work and to be introduced to the scientific diatom world. Despite the largely recognized role of diatoms for the planet (e.g. Schoefs, Hu, and Kroth (2017 Schoefs, B., H. Hu, and P. G. Kroth. 2017. “The Peculiar Carbon Metabolism in Diatoms.” Philosophical Transactions of the Royal Society B: Biological Sciences 372 (1728): 20160405. doi:10.1098/rstb.2016.0405.[Crossref], [Web of Science ®] , [Google Scholar])), the total number of taxa remains elusive and very regularly new genera and species are described (e.g. Dodinet, Nadot, and Schoefs (2019 Dodinet, E., S. Nadot, and B. Schoefs. 2019. “Editorial.” Botany Letters 166 (1): 1–2. doi:10.1080/23818107.2019.1583831.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar])). Diatom taxonomy mostly relies on the frustule organisation, including its ornamentation pattern. These morphological characteristics are crucial for the identification of taxa making a precise description of this ornamentation compulsary. The aim of the paper by Wetzel, Beauger, and Ector (2019 Wetzel, C. E., A. Beauger, and L. Ector. 2019. “Cocconeis Rouxii Héribaud & Brun a Forgotten, but Common Benthic Diatom Species from the Massif Central, France.” Botany Letters 1–13. doi:10.1080/23818107.2019.1584865.[Taylor & Francis Online] , [Google Scholar]) in this issue is to clarify the taxon Cocconeis rouxii Héribaud & Brun (Héribaud 1893 Héribaud, J. 1893. Les Diatomées d’Auvergne. Paris: Librairie des Sciences Naturelles. [Google Scholar]) from samples collected in the Auvergne region (France) using light and scanning electron microscopy whereas the contribution by Wadmare et al. (2019 Wadmare, N., S. Roy, J. P. Kociolek, and B. Karthick. 2019. “Two New Aerophilic Species of Stauroneis Ehrenberg (Bacillariophyta) from the Eastern Himalayas.” Botany Letters 1–12. doi:10.1080/23818107.2019.1602786.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) describes two new aerophilic species of Stauroneis in the Eastern Himalayas of India. The correct identification of diatom taxa is of prime importance for many aspects of diatom research, including biodiversity studies, the description and the evolution of diatom assemblages (e.g. Lai et al. (2019 Lai, G.G., Padedda, B.M., Wetzel, C.E., Cantonati, M., Sechi, N., Lugliè, A., and Ector, L. 2019. “Diatom Assemblages from Different Substrates of the Casteldoria Thermo-Mineral Spring (Northern Sardinia, Italy).” Botany Letters 166 (1): 14–31. doi:10.1080/23818107.2018.1466726.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar])), (paleo)distribution and (paleo)ecology (e.g. Prokopenko and Khursevich (2014 Prokopenko, A. A., and G. K. Khursevich. 2014. “Planktonic Diatom Flora of Large Rift Lakes in Continental Asia during the past 1 Ma: Comparison of Biostratigraphic Records from Lake Baikal and Lake Hovsgol.” Nova Hedwiga, Beiheft 143: 32–52. [Google Scholar])). Several papers published in this issue are related to these fields of research. First of all, Cocquyt, Mambweni Makaya, and Ngendja Kabitoma (2019 Cocquyt, C., J. Mambweni Makaya, and M. Ngendja Kabitoma. 2019. “Observation of Eunotia Enigmatica (Bacillariophyta), a Rare South-American Diatom Species, in the Congo Basin, Tropical Africa.” Botany Letters 1–8. doi:10.1080/23818107.2019.1602787.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) discuss the analysis of material collected in a river of the Congo basin (Democratic Republic of the Congo). Surprisingly but interestingly, they could identify an unusual Eunotia species as Eunotia enigmatica, a species that was recently described from Brazil (Costa et al. 2017 Costa, L. F., C. E. Wetzel, L. Ector, D. M. Williams, and D. C. Bicudo. 2017. “Eunotia Enigmatica Sp. Nov., A New Planktonic Diatom from Brazil and the Transfer of Fragilaria Braunii Hustedt to the Genus Peronia (Bacillariophyceae).” Fottea 17 (1): 103–113. doi:10.5507/fot.2016.023.[Crossref], [Web of Science ®] , [Google Scholar]). The relative abundance of the collected taxa revealed that E. enigmatica was a rather infrequent though not rare taxon. Beauger et al. (2019 Beauger, A., C. E. Wetzel, J.-L. Peiry, O. Voldoire, and L. Ector. 2019. “Craticula Widouensis, a New Diatom (Bacillariophyta) Species of a Sahelian Temporary Pond (North Senegal).” Botany Letters. doi:10.1080/23818107.2019.1623715.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) discovered a new species of Craticula in a pond in Northern Senegal. Many aspects of diatom life have still to be studied in details to understand their ecology and distribution. This includes answers to nutrient deficiency (e.g. Heydarizadeh et al. (2019 Heydarizadeh, P., Veidl, B., Huang, B., Lukomska, E., Wielgosz-Collin, G., Couzinet-Mossion, A., Bougaran, G., Marchand, J., and Schoefs, B. 2019. “Carbon Orientation in the Diatom Phaeodactylum Tricornutum: The Effects of Carbon Limitation and Photon Flux Density.” Frontiers in Plant Science 10: 471. doi:10.3389/fpls.2019.00471.[Crossref], [Web of Science ®] , [Google Scholar])) and the capacity to move. It is generally accepted that diatoms can move (Bertrand 2008 Bertrand, J. 2008. “Mouvements Des Diatomées VIII: Synthèse Et Hypothèse.” Diatom Research 23 (1): 19–29. doi:10.1080/0269249X.2008.9705734.[Taylor & Francis Online] , [Google Scholar]), sometimes in a response to a stimulus (Bondoc et al. 2016 Bondoc, K. G. V., C. Lembke, W. Vyverman, and G. Pohnert. 2016. “Searching for a Mate: Pheromone-Directed Movement of the Benthic Diatom Seminavis Robusta.” Microbial Ecology 72 (2): 287–294. doi:10.1007/s00248-016-0796-7.[Crossref], [Web of Science ®] , [Google Scholar]), or remain immobile, for instance as epiphytes (e.g. Bertrand et al. (2016 Bertrand, J., C. Coste, R. Le Cohu, J.-P. Renon, and L. Ector. 2016. “Étude Préliminaire Sur La Présence De Diatomées Sur Les Lichens.” Botany Letters 163 (2): 93–115. doi:10.1080/23818107.2016.1156573.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar])). In this issue, Roubeix and Chalié (2019 Roubeix, V., and F. Chalié. 2019. “Identification of an Epiphytic Diatom on Nitzschia Sigmoidea (Bacillariophyceae).” Botany Letters 1–5. doi:10.1080/23818107.2019.1568300.[Taylor & Francis Online] , [Google Scholar]) report a unique case of epiphytism: the phoretic epithytism of Fallacia helensis on Nitzschia sigmoidea. This original work opens new avenues for investigating the intra-relationships between the diatom species, phoretic epiphytism and its role in the dissemination of diatoms. In this frame the finding by Heudre et al. (2019 Heudre, D., C. E. Wetzel, B. Van de Vijver, L. Moreau, and L. Ector. 2019. “Two sub-Antarctic and Northern Europe Distributed Diatom Species Found in a Middle-Mountain Lake in France.” Botany Letters 1–9. doi:10.1080/23818107.2019.1584864.[Taylor & Francis Online] , [Google Scholar]) of two diatoms in a lake in the Vosges (France), presenting an unusual biogeographical distribution, is of interest because it makes us wonder how these rare taxa managed to disperse and develop in this peculiar environment.

Publication year:2019