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Article
Published: 2022-07-26

Fragilaria odeloucaensis sp. nov. (Bacillariophyta, Fragilariaceae) a diatom from temporary streams in southern Portugal

Water Laboratory, University of Évora, P.I.T.E. Rua da Barba Rala No. 1, 7005–345 Évora, Portugal; Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n° 59, 7000–671 Évora, Portugal
Water Laboratory, University of Évora, P.I.T.E. Rua da Barba Rala No. 1, 7005–345 Évora, Portugal; Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n° 59, 7000–671 Évora, Portugal
Environmental Research and Innovation Department (ERIN), Luxembourg Institute of Science and Technology (LIST), 41 rue du Brill, 4422 Belvaux, Luxembourg
Environmental Research and Innovation Department (ERIN), Luxembourg Institute of Science and Technology (LIST), 41 rue du Brill, 4422 Belvaux, Luxembourg
Water Laboratory, University of Évora, P.I.T.E. Rua da Barba Rala No. 1, 7005–345 Évora, Portugal; Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n° 59, 7000–671 Évora, Portugal
Araphid diatoms drylands Iberian Peninsula intermittent streams taxonomy Algae

Abstract

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 features within this group, the lanceolate valves with capitate apices, the zig-zagged axial area, the central area with squared fascia, the apical pore fields clearly sunken into the valve apices and the heterovalvar frustules (with respect to striae distancing). Ecological features of the type locality and an additional sampling point where the new species was found are given, together with a discussion of the taxonomic position of the new species within Fragilaria, and the approach used herein for the identification of diagnostic features. This approach includes a detailed analysis of the internal and external characteristics of the axial area-virgae-striae complex, central area, apical pore fields and differences among valves of the same frustule, in addition to the traditional valve shape and morphometric features.

References

  1. Acuña, V., Datry, T., Marshall, J., Barceló, D., Dahm, C.N., Ginebreda, A., McGregor, G., Sabater, S., Tockner, K. & Palmer, M.A. (2014) Why should we care about temporary waterways? Science 343: 1080–1081. https://doi.org/10.1126/science.1246666

  2. Almeida, P.D., Morales, E.A., Wetzel, C.E., Ector, L. & Bicudo, D.C. (2016) Two new diatoms in the genus Fragilaria Lyngbye (Fragilariophyceae) from tropical reservoirs in Brazil and comparison with type material of F. tenera. Phytotaxa 246: 163–183. https://doi.org/10.11646/phytotaxa.246.3.1

  3. A.P.A, I.P. (2016) Plano de gestão de região hidrografica 2016/2021. Parte 2 – Caracterização e Diagnóstico. Anexo IV. Agência Portuguesa do Ambiente, I.P. 35 pp.

  4. Barber, H.G. & Haworth, E.Y. (1981) A Guide to the Morphology of the Diatom Frustule with a Key to the British Freshwater Genera. Freshwater Biological Association Scientific Publication 44: 1–112.

  5. Barbosa, L.G., Amorim, C.A., Parra, G., Portinho, J.L., Moralis, M., Morales, E.A. & Menezes, R.F. (2020) Advances in limnological research in Earth´s drylands. Inland Waters 10: 429–437.  https://doi.org/10.1080/20442041.2020.1728179

  6. Bonada, N., Cañedo-Argüelles, M., Gallart, F., von Schiller, D., Fortuño, P., Latron, J., Llorens, P., Múrria, C., Soria, M., Vinyoles, D. & Cid, N. (2020) Conservation and management of isolated pools in temporary rivers. Water 12: 2870.  https://doi.org/10.3390/w12102870

  7. Brutschy, A. (1922) Die Vegetation und der Zooplankton des Hallwiller Sees (Schluß). Internationale Revue der gesamten Hydrobiologie 10: 271–298.  https://doi.org/10.1002/iroh.19220100304

  8. Cantonati, M., Angeli, N., Lange-Bertalot, H. (2019) Three new Fragilaria species (Bacillariophyta) from low-conductivity mountain freshwaters (Alps and Apennines). Phytotaxa 404: 261–274.  https://doi.org/10.11646/phytotaxa.404.6.5

  9. Cemagref (1982) Etude des méthodes biologiques quantitatives d’appréciation de la qualité des eaux. Rapport Division Qualité des Eaux Lyon - Agence financière de Bassin Rhône-Méditerranée-Corse, Pierre-Bénite, France.

  10. Chudaev, D., Jüttner, I. & Van de Vijver, B. (2021) Fragilaria irregularis sp. nov. a new araphid species (Fragilariaceae, Bacillariophyta) from the River Adegoy, Krasnodar Territory, Russia. Phytotaxa 508: 221–228.  https://doi.org/10.11646/phytotaxa.508.2.11

  11. Compère, P. (1986) Algues récoltées par J. Léonard dans le désert de Libye. Bulletin du Jardin Botanique National de Belgique 56 (1/2): 9–50.  https://doi.org/10.2307/3667756

  12. Compère, P. (2001) Ulnaria (Kützing) Compère, a new genus name for Fragilaria subgen. Alterasynedra Lange-Bertalot with comments on the typification of Synedra Ehrenberg. In: Jahn, R., Kociolek, J.P., Witkowski, A. & Compère, P. (Eds.) Lange-Bertalot Festschrift. Studies on diatoms dedicated to Prof. Dr. Dr. h.c. Horst Lange-Bertalot on the occasion of his 65th birthday. A.R.G. Gantner Verlag K.G., Ruggell, pp. 97–101.

  13. Cox, E.J. (2012) Ontogeny, homology, and terminology – wall morphogenesis as an aid to character recognition and character state definition for pennate diatom systematics. Journal of Phycology 48: 1–31.  https://doi.org/10.1111/j.1529-8817.2011.01081.x

  14. Cox, E.J. & Ross, R. (1981) The striae of pennate diatoms. In: Ross, R. (Ed.) Proceedings of the Sixth Symposium on Recent and Fossil Diatoms. Budapest, September 1–5, 1980, Otto Koeltz, Koenigstein, pp. 267–278.

  15. Czarnecki, D.B. (1994) The freshwater diatoms culture collection at Loras College, Dubuque, Iowa. In: Kociolek, J.P. (Ed.) Proceedings of the 11th International Diatom Symposium. Memoirs of the California Academy of Sciences 17: 155–174.

  16. Datry, T., Larned, S.T., Tockner, K. (2014) Intermittent rivers: A challenge for freshwater ecology. Bioscience 64: 229–235.  https://doi.org/10.1093/biosci/bit027

  17. Datry, T., Corti, R., Heino, J., Hugueny, B., Rolls, R.J. & Ruhí, A. (2018a) Habitat fragmentation and metapopulation, metacommunity, and metaecosystem dynamics in intermittent rivers. In: Datry, T., Bonada, N. & Boulton, A. (Eds.) Intermittent Rivers and Ephemeral Streams. Ecology and Management. Academic Press, Burlington, pp. 377–403.  https://doi.org/10.1016/B978-0-12-803835-2.00014-0

  18. Datry, T., Boulton, A.J., Bonada, N., Fritz, K., Leigh, C., Sauquet, E., Tockner, K., Hugueny, B. & Dahm, C.N. (2018b) Flow intermittence and ecosystem services in rivers of the Anthropocene. Journal of Applied Ecology 55: 353–364.  https://doi.org/10.1111/1365-2664.12941

  19. Delgado, C., Novais, M.H., Blanco, S. & Almeida, S.F.P. (2015) Examination and comparison of Fragilaria candidagilae sp. nov. with type material of Fragilaria recapitellata, F. capucina, F. perminuta, F. intermedia and F. neointermedia (Fragilariales, Bacillariophyta). Phytotaxa 231: 1–18.  https://doi.org/10.11646/phytotaxa.231.1.1

  20. Delgado, C., Novais, M.H., Blanco, S. & Almeida, S.F.P. (2016) Fragilaria rinoi sp. nov. (Fragilariales, Fragilariophyceae) from periphytic river samples in central Portugal. European Journal of Taxonomy 248: 1–16.  https://doi.org/10.5852/ejt.2016.248

  21. Ehrenberg, C.G. (1830) Organisation, Systematik, und geographisches Verhältnis der Infusionstierchen. In: Druckerei dei Koningliche Akademie der Wissenschaften. F. Dümmler, Berlin, 108 pp., pls. I–VIII.

  22. Ehrenberg, C.G. (1832) Über die Entwickelung und Lebensdauer der Infusionsthiere; nebst ferneren Beiträgen zu einer Vergleichung ihrer organischen Systeme. Abhandlungen der Königlichen Akademie Wissenschaften zu Berlin, Physikalische Klasse 1831: 1–154, pls I–IV.

  23. Heudre, D., Wetzel, C.E., Moreau, L. & Ector, L. (2018) Fragilaria druotiana sp. nov. a new epiphytic freshwater diatom species (Fragilariaceae, Bacillariophyta) in lakes of Northeastern France. Algological Studies 155: 1–13.

  24. Heudre, D., Wetzel, C.E., Moreau, L., Van de Vijver, B. & Ector, L. (2019) On the identity of the rare Fragilaria subconstricta (Fragilariaceae), with Fragilaria species forming ribbon-like colonies shortly reconsidered. Plant Ecology and Evolution 152: 327–339.  https://doi.org/10.5091/plecevo.2019.1619

  25. Hildebrand, M., Lerch, S.J.L. & Shrestha, R.P. (2018) Understanding diatom dell wall silicification—Moving forward. Frontiers in Marine Sciences 5: 125.  https://doi.org/10.3389/fmars.2018.00125

  26. Hofmann, G., Werum, M. & Lange-Bertalot, H. (2011) Diatomeen im Süßwasser-Benthos von Mitteleuropa. Bestimmungsflora Kieselalgen für die ökologische Praxis. Über 700 der häufigsten Arten und ihre Ökologie. A.R.G. Gantner Verlag K.G., Rugell, 908 pp.

  27. INAG I.P. (2008) Manual para a Avaliação Biológica da Qualidade da Agua em Sistemas Fluviais Segundo a Directiva-Quadro da Água – Protocolo de Amostragem e Análise para o Fitobentos – Diatomáceas., Ministério do Ambiente, do Ordenamento do Território e do Desenvolvimento Regional. Instituto da Água, I.P., Lisboa, 35 pp.

  28. Krammer, K. & Lange-Bertalot, H. (1986) Bacillariophyceae 1. Teil: Naviculaceae. In: Ettl, H. Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.) Süsswasserflora von Mitteleuropa 2/1, Gustav Fischer Verlag, Stuttgart, Jena, 876 pp.

  29. Krammer, K. & Lange-Bertalot, H. (1988) Bacillariophyceae 2. Teil: Bacillariaceae, Epithemiaceae, Surirellaceae. In: Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.) Süsswasserflora von Mitteleuropa 2/2, Gustav Fischer Verlag, Stuttgart, Jena, 596 pp.

  30. Krammer, K. & Lange-Bertalot, H. (1991a) Bacillariophyceae 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In: Ettl, H., Gerloff, J. Heynig, H. & Mollenhauer, D. (Eds.) Süsswasserflora von Mitteleuropa 2/3, Gustav Fischer Verlag, Stuttgart, Jena, 576 pp.

  31. Krammer, K. & Lange-Bertalot, H. (1991b) Bacillariophyceae 4. Teil: Achnanthaceae. Kritische Ergänzungen zu Navicula (Lineolatae) und Gomphonema. Gesamtliteraturverzeichnis Teil 1–4. In: Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.) Süsswasserflora von Mitteleuropa 2/4. Gustav Fischer Verlag, Stuttgart, Jena, 437 pp.

  32. Krahn, K.J., Schwarz, A., Wetzel, C.E., Cohuo-Durán, S., Daut, G., Macario-González, L., Pérez, L., Wang, J. & Schwalb, A. (2021) Three new needle-shaped Fragilaria species from Central America and the Tibetan Plateau. Phytotaxa 479: 1–22.  https://doi.org/10.11646/phytotaxa.479.1.1

  33. Kulikovskiy, M., Lange-Bertalot, H., Witkowski, A., Dorofeyuk, N.I. & Genkal, S.I. (2010) Diatom assemblages from Sphagnum bogs of the world. I. Nur bog in northern Mongolia. Bibliotheca Diatomologica 55: 1–326.

  34. Kulikovskiy, M., Lange-Bertalot, H., Annenkova, N., Gusev, E. & Kociolek, J.P. (2016) Morphological and molecular evidence support description of two new diatom species from the genus Ulnaria in Lake Baikal. Fottea 16: 34–42.  https://doi.org/10.5507/fot.2015.011

  35. Lange-Bertalot, H., Hofmann, G., Werum, M. & Cantonati, M. (2017) In: Cantonati, M., Kelly, M.G. & Lange-Bertalot, H. (Eds.) Freshwater Benthic Diatoms of Central Europe: Over 800 Common Species Used in Ecological Assessment. English Edition with Updated Taxonomy and Added Species. Koeltz Botanical Books, Schmitten-Oberreifenberg, 942 pp.

  36. Lange-Bertalot, H. & Ulrich, S. (2014) Contributions to the taxonomy of needle-shaped Fragilaria and Ulnaria species. Lauterbornia 78: 1–73.

  37. Lange-Bertalot, H. & Steindorf, A. (1996) Rote Liste der limnischen Kieselalgen (Bacillariophyceae). Schriftenreihe für Vegetationskunde 28: 633–677.

  38. Larned, S.T., Dartry, T., Arscott, D.B. & Tockner, K. (2010) Emerging concepts in temporary-river ecology. Freshwater Biology 55: 717–738.  https://doi.org/10.1111/j.1365-2427.2009.02322.x

  39. Lecointe, C., Coste, M. & Prygiel, J. (1993) “Omnidia”: software for taxonomy, calculation of diatom indices and inventories management. Hydrobiologia 269/270: 509–513.  https://doi.org/10.1007/BF00028048

  40. Liu, B., Williams, D.M., Blanco, S., Liu, Z.-X. & Liu, D. (2019) Three new species of Ulnaria (Kützing) Compère (Bacillari­ophyta) from China, with reference to the fine structure of their valvocopula. Cryptogamie, Algologie 40: 119–139.  https://doi.org/10.5252/cryptogamie-algologie2019v40a11

  41. McDonough, O.T., Hosen, J.D. & Palmer, M. (2011) Temporary streams: The hydrology, geography, and ecology of non-perennially flowing waters. In: Elliot, H.S. & Martin, L.E. (Eds.) River ecosystems: Dynamics, management, and conservation. Nova Science Publishers, Inc., New York, pp. 259–289.

  42. Mock, T., Samanta, M.P., Iverson, V. & Armbrust, V.E. (2008) Whole-genome expression profiling of the marine diatom Thalassiosira pseudonana identifies genes involved in silicon bioprocesses. PNAS 105: 1579–1584.  https://doi.org/10.1073/pnas.0707946105

  43. Morales, E.A. (2003) Fragilaria pennsylvanica, a new diatom (Bacillariophyceae) species from North America, with comments on the taxonomy of the genus Synedra Ehrenberg. Proceedings of the Academy of Natural Sciences of Philadelphia 153: 155–166.  https://doi.org/10.1635/0097-3157(2003)153[0155:FPANDB]2.0.CO;2

  44. Morales, E.A. (2021) Punctastriata altera sp. nov. (Bacillariophyta, Fragilariophyceae), a diatom from the United States of America. Phytotaxa 516: 296–300.  https://doi.org/10.11646/phytotaxa.516.3.9

  45. Morales, E.A., Fernández, E. & Kociolek, P.J. (2009) Epilithic diatoms (Bacillariophyta) from cloud forest and alpine streams in Bolivia, South America 3: diatoms from Sehuencas, Carrasco National Park, Department of Cochabamba. Acta Botanica Croatica 68 (2): 263–283.

  46. Morales, E.A., Rivera, S.F., Wetzel, C.E., Novais, M.H., Hamilton, P.B., Hoffmann, L. & Ector, L. (2014) New epiphytic araphid diatoms in the genus Ulnaria (Bacillariophyta) from Lake Titicaca, Bolivia. Diatom Research 29: 41–54.  https://doi.org/10.1080/0269249X.2013.860399

  47. Morales, E.A., Wetzel, C.E. & Ector, L. (2021a) New and poorly known “araphid” diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in “araphid” diatom taxonomy. Phytokeys 187: 23–70.  https://doi.org/10.3897/phytokeys.187.73338

  48. Morales, E.A., Novais, M.H., García, M.L., Maidana, N.I. & Morais, M.M. (2021b) A new species of Punctastriata (Bacillariophyta, Fragilariophyceae) from temporary rivers in southern Portugal. Phytotaxa 507: 261–265.  https://doi.org/10.11646/phytotaxa.507.3.3

  49. Morales, E.A., Novais, M.H., García, M.L., Maidana, N.I. & Morais, M.M. (2021c) Planothidium audax sp. nov. (Bacillariophyta, Achnanthidiaceae), a new diatom from temporary streams in southern Portugal. Phytotaxa 510: 288–294.  https://doi.org/10.11646/phytotaxa.510.3.9

  50. Nitzsch, C.L. (1817) Beitrag zur Infusorienkunde oder Naturbeschreibung der Zerkarien und Bazillarien. Neue Schriften der Naturforschenden Gesellschaft zu Halle 3 (1): 1–128.

  51. Novais, M.H. (2011) Estudo das diatomáceas bênticas em sistemas lóticos de Portugal Continental / Benthic diatoms in Portuguese watercourses. University of Evora, Ph.D. Thesis. Vol. I: 242 pp., Vol. II: 601 pp.

  52. Novais, M.H., Hlúbiková, D., Morais, M., Hoffmann, L. & Ector, L. (2011) Morphology and ecology of Achnanthidium caravelense (Bacillariophyceae), a new species from Portuguese rivers. Algological Studies 136/137: 131–150.  https://doi.org/10.1127/1864-1318/2011/0136-0131

  53. Novais, M.H., Morais, M.M., Rosado, J., Dias, L.S., Hoffmann, L. & Ector, L. (2014) Diatoms of temporary and permanent watercourses in southern Europe (Portugal). River Research and Applications 30: 1213–1232. https://doi.org/10.1002/rra.2818

  54. Novais, M.H., Almeida, S.F.P., Blanco, S. & Delgado, C. (2019) Morphology and ecology of Fragilaria misarelensis sp. nov. (Bacillariophyta), a new diatom species from southwest of Europe. Phycologia 58: 128–144.  https://doi.org/10.1080/00318884.2018.1524245

  55. Novais, M.H., Morales, E.A., Penha, M.A., Potes, M., Bouchez, A., Barthès, A., Costa, M.J., Salgado, R., Santos, J. & Morais, M. (2020) Benthic diatom community dynamics in Mediterranean intermittent streams: Effects of water availability and their potential as indicators of dry-phase ecological status. Science of the Total Environment (STOTEN) 719: 137462.  https://doi.org/10.1016/j.scitotenv.2020.137462

  56. Østrup, E. (1910) Danske Diatoméer med 5 tavler et Engelsk résumé. Udgivet paa Carlsbergfondets bekostning. C.A. Reitzel Boghandel Bianco Lunos Bogtrykkeri, Kjøbenhavn [Copenhagen], pp. [i]–xi, 1–323, pls 1–5.  https://doi.org/10.5962/bhl.title.1044

  57. Reichardt, E. (1997) Taxonomische Revision des Artenkomplexes um Gomphonema pumilum (Bacillariophyceae). Nova Hedwigia 65 (1–4): 99–129.  https://doi.org/10.1127/nova.hedwigia/65/1997/99

  58. Rioual, P., Flower, R.J., Chu, G., Lu, Y., Zhang, Z., Zhu, B. & Yang, X. (2017) Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushford. Phytotaxa 329: 28–50.  https://doi.org/10.11646/phytotaxa.329.1.2

  59. Round, F.E., Crawford, R.M. & Mann, D.G. (1990) The Diatoms: Biology & Morphology of the Genera. Cambridge University Press, Cambridge, U.S.A., 747 pp.

  60. Round, F.E. & Bukhtiyarova, L. (1996) Four new genera based on Achnanthes (Achnanthidium) together with a re-definition of Achnanthidium. Diatom Research 11: 345–361. https://doi.org/10.1080/0269249X.1996.9705389

  61. Schmidt, A.[W.F.] (1902) Atlas der Diatomaceen-kunde Series V: Heft 59[/60]. [M. Schmidt & F. Fricke]. O.R. Reisland, Leipzig. pls 233–240.

  62. Sabater, S., Timoner, X., Borrego, C. & Acuña, V. (2016) Stream biofilm responses to flow intermittency: from cells to ecosystems. Frontiers in Environmental Science 4: 14.  https://doi.org/10.3389/fenvs.2016.00014

  63. Brembu, T., Chauton, M.S., Winge, P., Bones, A.M. & Vadstein, O. (2017) Dynamic responses to silicon in Thalasiossira pseudonana—Identification, characterisation and classification of signature genes and their corresponding protein motifs. Scientific Reports 7: 4865. https://doi.org/10.1038/s41598-017-04921-0

  64. Tuji, A. (2007) Type examination of Fragilaria gracilis Østrup (Bacillariophyceae). Bulletin of the Museum of Nature and Science, Series B 33: 9–12.

  65. Tuji, A. (2009) The transfer of two Japanese Synedra species (Bacillariophyceae) to the genus Ulnaria. Bulletin of the Museum of Nature and Science, Series B 35: 11–16.

  66. Tuji, A. & Williams, D.M. (2006a) Typification of Conferva pectinalis O. F. Müll. (Bacillariophyceae) and the identity of the type of an alleged synonym, Fragilaria capucina Desm. Taxon 55: 193–199.  https://doi.org/10.2307/25065541

  67. Tuji, A. & Williams, D.M. (2006b) Examination of the type material of Synedra rumpens = Fragilaria rumpens, Bacillariophyceae. Phycological Research 54: 99–103.  https://doi.org/10.1111/j.1440-1835.2006.00414.x

  68. Tuji, A. & Williams, D.M. (2008a) Examination of the type material of Fragilaria mesolepta Rabenhorst and two similar, but distinct, taxa. Diatom Research 23: 503–510.  https://doi.org/10.1080/0269249X.2008.9705772

  69. Tuji, A. & Williams, D.M. (2008b) Examination of types in the Fragilaria pectinaliscapitellata species complex. In: Likhoshway, Y. (Ed.) Nineteenth International Diatom Symposium. Briopress Limited, Bristol, pp. 125–139.

  70. Várbíró, G., Borics, G., Novais, M.H., Morais, M.M., Rimet, F., Bouchez, A., Topolczai, K., Bácsi, I., Usseglio-Polatera, P. & B-Béres, V. (2020) Environmental filtering and limiting similarity as main forces driving diatom community structure in Mediterranean and continental temporary and perennial streams. Science of the Total Environment 741: 140459.  https://doi.org/10.1016/j.scitotenv.2020.140459

  71. Van de Vijver, B. & Ector, L. (2020) Analysis of the type material of Synedra perminuta (Bacillariophyceae) with the description of two new Fragilaria species from Sweden. Phytotaxa 468: 89–100.  https://doi.org/10.11646/phytotaxa.468.1.5

  72. Van de Vijver, B., Ector, L., Beltrami, M.E., de Haan, M., Falasco, E., Hlúbiková, D., Jarlman, D., Kelly, M., Novais, M.H. & Wojtal, A.Z. (2011) A critical analysis of the type material of Achnanthidium lineare W. Sm. (Bacillariophyceae). Algological Studies 136/137: 167–191.  https://doi.org/10.1127/1864-1318/2011/0136-0167

  73. Van de Vijver, B., Mertens, A. & Ector, L. (2020a) Analysis of the type material of Synedra deformis W.Sm. and Synedra vaucheriae var. deformis Grunow (Fragilariaceae, Bacillariophyta). Cryptogamie, Algologie 41: 137–149.  https://doi.org/10.5252/cryptogamie-algologie2020v41a13

  74. Van de Vijver, B., Straub, F., Wetzel, C.E. & Ector, L. (2020b) Observations on and epityfication of Synedra austriaca Grunow (Fragilariaceae, Bacillariophyta). Notulae algarum No. 130.

  75. Van de Vijver, B., Tusset, E., Williams, D.M. & Ector, L. (2020c) Analysis of the type specimens of Fragilaria alpestris (Bacillariophyta) with description of two new “araphid” species from the sub-Antarctic and the Arctic Region. Phytotaxa 471: 1–15.  https://doi.org/10.11646/phytotaxa.471.1.1

  76. Van de Vijver, B., Alexson, E.E., Reavie, E.D., Straub, F., Steinn Jónsson, G. & Ector, L. (2021a) Analysis of the type of Synedra acus var. ostenfeldii (Bacillariophyta) and its transfer to the genus Fragilaria. Bottany Letters 168: 85–95.  https://doi.org/10.1080/23818107.2020.1845973

  77. Van de Vijver, B., Hürlimann, J., Williams, D.M., Levkov, Z., Wetzel, C.E. & Ector, L. (2021b) Fragilaria subrecapitellata (Fragilariaceae, Bacillariophyta), a new diatom species from Switzerland. Diatom Research 36: 119–131.  https://doi.org/10.1080/0269249X.2021.1942221

  78. Van de Vijver, B., Hürlimann, J., Potapova, M.P., Bahls, L., Ballings, P., Levkov, Z., Kusber, W-H. & Ector, L. (2021c) Observations and typification of Fragilaria cyclopum (Brutschy) Lange-Bertalot (Fragilariaceae, Bacillariophyta). Notulae Algarum No. 204.

  79. Van de Vijver, B., Williams, D.M., Schuster, T.M., Kusber, W-H., Cantonati, M., Wetzel, C.E. & Ector, L. (2022) Analysis of the Fragilaria rumpens complex (Fragilariaceae, Bacillariophyta) with the description of two new species. Fottea 22: 93–121.  https://doi.org/10.5507/fot.2021.018

  80. Wengrat, S., Morales, E.A., Wetzel, C.E., Almeida, P.D., Ector, L. & Bicudo, D.C. (2016) Taxonomy and ecology of Fragilaria billingsii sp. nov. and analysis of type material of Synedra rumpens var. fusa (Fragilariaceae, Bacillariophyta) from Brazil. Phytotaxa 270: 191–202.  https://doi.org/10.11646/phytotaxa.270.3.3

  81. Wetzel, C.E. & Ector, L. (2015) Taxonomy and ecology of Fragilaria microvaucheriae sp. nov. and comparison with the type materials of F. uliginosa and F. vaucheriae. Cryptogamie, Algologie 36: 271–289.  https://doi.org/10.7872/crya/v36.iss3.2015.271

  82. Williams, D.M. (1986) Comparative morphology of some species of Synedra with a new definition of the genus. Diatom Research 1: 131–152.  https://doi.org/10.1080/0269249X.1986.9704963

  83. Williams, D.M. (2011) Synedra, Ulnaria: definitions and descriptions – a partial resolution. Diatom Research 26: 149–153.  https://doi.org/10.1080/0269249X.2011.587646

  84. Williams, D.M. (2019) Studies on type material from Kützing´s diatom collection I: Synedra vitrea Kützing, with comments on Ulnaria fragilariaeformis (F.E. Fritsch and M.F. Rich) D.M. Williams, nov. stat. et nov. comb. and Ulnaria undulata (Rabenhorst) D.M. Williams, nov. stat. et nov. comb. Botanical Letters 167: 70–85.  https://doi.org/10.1080/23818107.2019.1683067

  85. Williams, D.M. & Round, F.E. (1988 “1987”) Revision of the genus Fragilaria. Diatom Research 2: 267–288.  https://doi.org/10.1080/0269249X.1987.9705004

  86. Williams, D.M. & Van de Vijver, B. (2021) Studies on type material from Kützing´s diatom collection III: Synedra splendens (Kütz.) Kütz., Synedra aequealis (Kütz.) Kütz. and a note on Synedra obtusa W.Sm. Fottea 21: 164–179.  https://doi.org/10.5507/fot.2021.004