Abstract
Modern diatom assemblages were investigated in the Ounianga Lakes located in the driest part of the Chadian Sahara. These lakes still exist today due to groundwater seepage. They contain a variety of diatom species, one of which could not be identified. Here we describe a new species of Staurophora, S. ouniangaensis sp. nov. based on detailed light and scanning electron microscopy observations. The new taxon presents all morphological characters attributed to this genus and differs from other Staurophora species mainly by its specific valve outline and the slightly twisted frustules along the transapical axis. We compared this new species with the morphologically resembling Cymbella obtusa which was reported from Chad. The latter taxon has a much coarser stria density than our newly described species. Staurophora ouniangaensis sp. nov. supports that Staurophora species prefer inland saline environments. Indeed, in the Ounianga lakes, the new species was mainly observed in mesosaline to hypersaline waters.
References
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Bahls, L.L. (2013) New diatoms (Bacillariophyta) from western North America. Phytotaxa 82: 7–28. https://doi.org//10.11646/phytotaxa.82.1.2
Bahls, L.L. (2015) Kurtkrammeria, a new genus of freshwater diatoms (Bacillariophyta, Cymbellaceae) separated from Encyonopsis. Nova Hedwigia 101 (1/2): 165–190. https://doi.org/10.1127/nova_hedwigia/2015/0263
Capot-Rey, R. (1961) Borkou et Ounianga: étude de géographie régionale. Mémoire 5. Institut de recherches sahariennes, Algiers, 182 pp.
Cocquyt, C. (2004) Staurophora caljonii spec. nov. (Bacillariophyceae Anomoeoneidaceae), a new halophilic diatom species from sub-recent lake deposits in Kenya. Hydrobiologia 511: 37–46. https://doi.org/10.1023/B:HYDR.0000014017.38481.62
Desianti, N., Potapova, M. & Beals, J. (2015) Examination of the type materials of diatoms described by Hohn and Hellerman from the Atlantic Coast of the USA. Diatom Research 30 (2): 93–116. https://doi.org/10.1080/0269249X.2014.1000020
Ehrenberg, C.G. (1830) Organisation, systematik und geographisches verhältniss der infusionsthierchen. Zwei vorträge, in der Akademie der wissenschaften zu Berlin gehalten in den jahren 1828 und 1830. pp. 1–108, pls I–VIII; Kupfertafeln (copper pls.).
Ehrenberg, C.G. (1843) Mitteilungen über 2 neue asiatische Lager fossiler Infusorien-Erden aus dem russischen Trans-Kaukasien (Grusien) und Sibirien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1843: 43–49.
Foged, N. (1966) Freshwater diatoms from Ghana. Det Kongelige Danske Videnskabernes Selskab, Biologiske Shrifter 15 (1): 1–169.
Foged, N. (1982) Diatoms in Bornholm, Denmark. Bibliotheca Phycologia 59: 1–175.
Foged, N. (1986) Diatoms in Gambia. Bibliotheca Diatomologica 12: 1–152.
Gasse, F., Juggins, F. & Ben Khelifa, L. (1995) Diatom-based transfer functions for inferring past hydrochemical chatacteristics of African lakes. Palaeogeography, Palaeoclimatology, Palaeoecology 117: 31–54. https://doi.org/10.1016/0031-0182(94)00122-O
Giffen, M.H. (1967) Contributions to the diatom flora of South Africa III. Diatoms of the marine littoral regions at Kidd’s Beach near east London, Cape Province, South Afrika. Nova Hedwigia 13: 245–292.
Google Earth Pro (2021) Ounianga region, Chad. Available from: http://www.google.com/earth/index.html (accessed 29 september 2021)
Gregory, W. (1856) Notice of some new species of British Fresh-water Diatomaceae. Quarterly Journal of Microscopical Science, new series, London 4: 1–14, pl. I.
Greville, R.K. (1855) Report on a collection of Diatomaceae made in the district of Braemar by Professor Balfour and Mr. George Lawson. Annals and Magazine of Natural History, 2nd series 15: 252–261, pl. IX. https://doi.org/10.1080/037454809495417
Grunow, A. (1862) Die österreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitäten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 12: 315–472 [Abt 1], 545–588 [Abt. 2], 7 pls.
Guiry, M.D. & Guiry, G.M. (2022) AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Available from: http://www.algaebase.org (searched 17 February 2022)
Hustedt, F. (1945) Diatomeen aus Seen und Quellgebieten der Balkan-Halbinsel. Archiv für Hydrobiologie 40: 867–973.
Hustedt, F. (1949) Süsswasser-Diatomeen aus dem Albert Nationalpark in Belgisch-Kongo. Exploration du Parc National Albert, Mission H. Dumas 8: 1–199.
Hustedt, F. (1959) Die Diatomeenflora des Salzlackengebietes im Österreichische Burgenland. Österreichischen Akademie der Wissenschaften, Mathematische und Naturwissenschaftlichen Klasse 168: 387–452.
Krammer, K. (1997) Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema Part., Encyonopsis und Cymbellopsis. Bibliotheca Diatomologica 37: 1–469.
Krasske, G. (1927) Diatomeen deutscher Solquellen und Gradierwerke. Archiv für Hydrobiologie 18: 252–72.
Kröpelin, S. (2007) The Saharan lakes of Ounianga Serir – a unique hydrogeological system. In: Bubenzer, O., Bolten, A. & Darius, F. (Eds.) Atlas of Cultural and Environmental Change in Arid Africa. Africa Praehistorica 21: 54–55.
Kröpelin, S., Verschuren, D., Lézine, A.-M., Eggermont, H., Cocquyt, C., Francus, P., Cazet, J.-P., Fagot, M., Rumes, B., Russell, J.M., Darius, F., Conley, D.J., Schuster, M., von Suchodoletz, H. & Engstrom, D.R. (2008) Climate-driven ecosystem succession in the Sahara: the last 6000 years. Science 320 (5877): 765–768. https://doi.org/10.1126/science.1154913
Lange-Bertalot, H. & Krammer, K. (1987) Bacillariaceae, Epithemiaceae, Surirellaceae. Neue und wenig bekannte Taxa, neue Kombinationen und Synonyme sowie Bemerkungen und Ergänzungen zu den Naviculaceae. Bibliotheca Diatomologica 15: 1–289.
Maidana, N.I.,Seeligann, C. & Morales, M. (2009) Bacillariophyceae del complejo lagunar Vilama (Jujuy, Argentina). Boletín de la Sociedad Argentina de Botánica 4 (3/4): 257–271.
Mereschkowsky, K.S. (1903) Bacillariophyceae. Beihefte zum Botanischen Centralblatt 15: 1–30.
Müller, O. (1899) Rhopalodia ein neues Genus der Bacillariaceen. Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 22 (1): 54–71.
Poretzsky, V.S. & Anisimoca, N.V. (1933) Materialy k ekologii diatomovykh Starorusskikh solenykh vodoemov [Materials on ecology of the diatoms of saltwater basins of Staraia Russa]. Issledovaniia ozer Soyuza S.S.R. Gosudarstvennyi Gidrologicheskii Institut Leningrad 2: 31–66.
Poulin, C. (2018) Bilan hydrologique et étude de la recharge de trois systèmes lac-aquifère du Bassin du lac Tchad par une approche géochimique multi traceurs (d<sup>18</sup>O, d<sup>2</sup>H, <sup>36</sup>Cl, <sup>14</sup>C). Thèse de Doctorat CEREGE– Aix-Marseille Université, 145 pp.
Reinhold, T. (1937) La flore fossile à diatomées de Moliro (Lac Tanganyika Katanga). Annales de la Société Géologique de Belgique, Mémoires 61: 39–47.
Rirongarti, R. (2019) Etude des diatomées actuelles des lacs du Tchad: Taxonomie, Diversité et Calibration. Thèse de Doctorat CEREGE–Aix-Marseille Université, 166 pp.
Rirongarti, R., Sylvestre, F., Paillès, C, Chalié, F., Mazur, J.C, Mahamat Nour, A., Barthelemy, W., Mariot, H., Van der Meeren, T., Poulin, C., Deschamps, P., Abderamane, M. A diatom-based predictive model for inferring past conductivity in Chadian Sahara lakes. Journal of Paleolimnology. [In review]
Round, F.E. (1961a) The composition of some diatomites from the Southern Sahara. Journal of the Royal Microscopical Society 80 (1): 59–69. https://doi.org/10.1111/j.1365-2818.1961.tb00467.x
Round, F.E. (1961b) Some Algae from the Ennedi Mountains of French Equatorial Africa. Journal of the Royal Microscopical Society 80 (1): 71–82. https://doi.org/10.1111/j.1365-2818.1961.tb00468.x
Round, F.E., Crawford, R.M. & Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
Simonsen, R. (1979) The diatom system: ideas on phylogeny. Bacillaria 2: 9–71.
Smith, W. (1853) A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens. Vol. 1. John van Voorst, London. pp. [i–vi] – xxxiii, 1–89, pls I–XXXI. https://doi.org/10.5962/bhl.title.10706
Smith, W. (1856) A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens. Vol. 2. John van Voorst, London. pp. [i–vi] – xxix, 1–107, pls 32–60, 61–62, A–E. https://doi.org/10.5962/bhl.title.10706
Smith, T.E., Smith, C.J. & Nii Yemog Annang, T. (2015) Taxonomic catalogue of algae from Ghana (Africa) and new additions. Algae Press, Ave Maria, Florida, 101 pp.
Taylor, J.C. & Cocquyt, C. (2016) Diatoms from the Congo and Zambezi Basins – Methodologies and identification of the genera. ABC Taxa 16: 1–353.
Thwaites, G.H.K. (1848) Further observations on the Diatomaceae with descriptions of new genera and species. Annals and Magazine of Natural History, Series 2 1: 161–172, pls XI, XII. https://doi.org/10.1080/03745485809496091
UNESCO (2015) Rapport sur l’état de conservation des lacs d’Ounianga. Available from: https://whc.unesco.org/fr/list/1400/ (accessed 10 August 2022)
Van der Meeren, T., Deschamps, P., Sylvestre, F., Kemkong, V., Abderamane, M., Schuster, M. & Verschuren, D. (2019) Les lacs d’Ounianga: mieux comprendre leur dynamique hydrologique et écologique à long terme à travers l’’étude intégrée de leurs archives sédimentaires et de la limnologie et l’écologie aquatique actuelles. In: Raimond, C., Sylvestre, F., Zakinet, D. & Abderamane, M. (Eds.) Le Tchad des Lacs. Collection Synthèse IRD, pp. 127–138.
Van der Meeren, T., Verschuren, D., Sylvestre, F., Nassour, Y.A., Naudts, E.L., Aguilar Ortiz, L.E., Deschamps, P., Tachikawa, K., Bard, E., Schuster, M., Abderamane, M. (2022) A predominantly tropical influence on late Holocene hydroclimate variation in the hyperarid central Sahara. Science Advances 8 (14): eabk1261. https://doi.org/10.1126/sciadv.abk1261
Van Heurck, H. (1881) Synopsis des Diatomées de Belgique Atlas. Ducaju et Cie, Anvers. pls XXXI–LXXVII.
Bahls, L.L. (2013) New diatoms (Bacillariophyta) from western North America. Phytotaxa 82: 7–28. https://doi.org//10.11646/phytotaxa.82.1.2
Bahls, L.L. (2015) Kurtkrammeria, a new genus of freshwater diatoms (Bacillariophyta, Cymbellaceae) separated from Encyonopsis. Nova Hedwigia 101 (1/2): 165–190. https://doi.org/10.1127/nova_hedwigia/2015/0263
Capot-Rey, R. (1961) Borkou et Ounianga: étude de géographie régionale. Mémoire 5. Institut de recherches sahariennes, Algiers, 182 pp.
Cocquyt, C. (2004) Staurophora caljonii spec. nov. (Bacillariophyceae Anomoeoneidaceae), a new halophilic diatom species from sub-recent lake deposits in Kenya. Hydrobiologia 511: 37–46. https://doi.org/10.1023/B:HYDR.0000014017.38481.62
Desianti, N., Potapova, M. & Beals, J. (2015) Examination of the type materials of diatoms described by Hohn and Hellerman from the Atlantic Coast of the USA. Diatom Research 30 (2): 93–116. https://doi.org/10.1080/0269249X.2014.1000020
Ehrenberg, C.G. (1830) Organisation, systematik und geographisches verhältniss der infusionsthierchen. Zwei vorträge, in der Akademie der wissenschaften zu Berlin gehalten in den jahren 1828 und 1830. pp. 1–108, pls I–VIII; Kupfertafeln (copper pls.).
Ehrenberg, C.G. (1843) Mitteilungen über 2 neue asiatische Lager fossiler Infusorien-Erden aus dem russischen Trans-Kaukasien (Grusien) und Sibirien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1843: 43–49.
Foged, N. (1966) Freshwater diatoms from Ghana. Det Kongelige Danske Videnskabernes Selskab, Biologiske Shrifter 15 (1): 1–169.
Foged, N. (1982) Diatoms in Bornholm, Denmark. Bibliotheca Phycologia 59: 1–175.
Foged, N. (1986) Diatoms in Gambia. Bibliotheca Diatomologica 12: 1–152.
Gasse, F., Juggins, F. & Ben Khelifa, L. (1995) Diatom-based transfer functions for inferring past hydrochemical chatacteristics of African lakes. Palaeogeography, Palaeoclimatology, Palaeoecology 117: 31–54. https://doi.org/10.1016/0031-0182(94)00122-O
Giffen, M.H. (1967) Contributions to the diatom flora of South Africa III. Diatoms of the marine littoral regions at Kidd’s Beach near east London, Cape Province, South Afrika. Nova Hedwigia 13: 245–292.
Google Earth Pro (2021) Ounianga region, Chad. Available from: http://www.google.com/earth/index.html (accessed 29 september 2021)
Gregory, W. (1856) Notice of some new species of British Fresh-water Diatomaceae. Quarterly Journal of Microscopical Science, new series, London 4: 1–14, pl. I.
Greville, R.K. (1855) Report on a collection of Diatomaceae made in the district of Braemar by Professor Balfour and Mr. George Lawson. Annals and Magazine of Natural History, 2nd series 15: 252–261, pl. IX. https://doi.org/10.1080/037454809495417
Grunow, A. (1862) Die österreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitäten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 12: 315–472 [Abt 1], 545–588 [Abt. 2], 7 pls.
Guiry, M.D. & Guiry, G.M. (2022) AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Available from: http://www.algaebase.org (searched 17 February 2022)
Hustedt, F. (1945) Diatomeen aus Seen und Quellgebieten der Balkan-Halbinsel. Archiv für Hydrobiologie 40: 867–973.
Hustedt, F. (1949) Süsswasser-Diatomeen aus dem Albert Nationalpark in Belgisch-Kongo. Exploration du Parc National Albert, Mission H. Dumas 8: 1–199.
Hustedt, F. (1959) Die Diatomeenflora des Salzlackengebietes im Österreichische Burgenland. Österreichischen Akademie der Wissenschaften, Mathematische und Naturwissenschaftlichen Klasse 168: 387–452.
Krammer, K. (1997) Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema Part., Encyonopsis und Cymbellopsis. Bibliotheca Diatomologica 37: 1–469.
Krasske, G. (1927) Diatomeen deutscher Solquellen und Gradierwerke. Archiv für Hydrobiologie 18: 252–72.
Kröpelin, S. (2007) The Saharan lakes of Ounianga Serir – a unique hydrogeological system. In: Bubenzer, O., Bolten, A. & Darius, F. (Eds.) Atlas of Cultural and Environmental Change in Arid Africa. Africa Praehistorica 21: 54–55.
Kröpelin, S., Verschuren, D., Lézine, A.-M., Eggermont, H., Cocquyt, C., Francus, P., Cazet, J.-P., Fagot, M., Rumes, B., Russell, J.M., Darius, F., Conley, D.J., Schuster, M., von Suchodoletz, H. & Engstrom, D.R. (2008) Climate-driven ecosystem succession in the Sahara: the last 6000 years. Science 320 (5877): 765–768. https://doi.org/10.1126/science.1154913
Lange-Bertalot, H. & Krammer, K. (1987) Bacillariaceae, Epithemiaceae, Surirellaceae. Neue und wenig bekannte Taxa, neue Kombinationen und Synonyme sowie Bemerkungen und Ergänzungen zu den Naviculaceae. Bibliotheca Diatomologica 15: 1–289.
Maidana, N.I.,Seeligann, C. & Morales, M. (2009) Bacillariophyceae del complejo lagunar Vilama (Jujuy, Argentina). Boletín de la Sociedad Argentina de Botánica 4 (3/4): 257–271.
Mereschkowsky, K.S. (1903) Bacillariophyceae. Beihefte zum Botanischen Centralblatt 15: 1–30.
Müller, O. (1899) Rhopalodia ein neues Genus der Bacillariaceen. Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie 22 (1): 54–71.
Poretzsky, V.S. & Anisimoca, N.V. (1933) Materialy k ekologii diatomovykh Starorusskikh solenykh vodoemov [Materials on ecology of the diatoms of saltwater basins of Staraia Russa]. Issledovaniia ozer Soyuza S.S.R. Gosudarstvennyi Gidrologicheskii Institut Leningrad 2: 31–66.
Poulin, C. (2018) Bilan hydrologique et étude de la recharge de trois systèmes lac-aquifère du Bassin du lac Tchad par une approche géochimique multi traceurs (d<sup>18</sup>O, d<sup>2</sup>H, <sup>36</sup>Cl, <sup>14</sup>C). Thèse de Doctorat CEREGE– Aix-Marseille Université, 145 pp.
Reinhold, T. (1937) La flore fossile à diatomées de Moliro (Lac Tanganyika Katanga). Annales de la Société Géologique de Belgique, Mémoires 61: 39–47.
Rirongarti, R. (2019) Etude des diatomées actuelles des lacs du Tchad: Taxonomie, Diversité et Calibration. Thèse de Doctorat CEREGE–Aix-Marseille Université, 166 pp.
Rirongarti, R., Sylvestre, F., Paillès, C, Chalié, F., Mazur, J.C, Mahamat Nour, A., Barthelemy, W., Mariot, H., Van der Meeren, T., Poulin, C., Deschamps, P., Abderamane, M. A diatom-based predictive model for inferring past conductivity in Chadian Sahara lakes. Journal of Paleolimnology. [In review]
Round, F.E. (1961a) The composition of some diatomites from the Southern Sahara. Journal of the Royal Microscopical Society 80 (1): 59–69. https://doi.org/10.1111/j.1365-2818.1961.tb00467.x
Round, F.E. (1961b) Some Algae from the Ennedi Mountains of French Equatorial Africa. Journal of the Royal Microscopical Society 80 (1): 71–82. https://doi.org/10.1111/j.1365-2818.1961.tb00468.x
Round, F.E., Crawford, R.M. & Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
Simonsen, R. (1979) The diatom system: ideas on phylogeny. Bacillaria 2: 9–71.
Smith, W. (1853) A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens. Vol. 1. John van Voorst, London. pp. [i–vi] – xxxiii, 1–89, pls I–XXXI. https://doi.org/10.5962/bhl.title.10706
Smith, W. (1856) A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens. Vol. 2. John van Voorst, London. pp. [i–vi] – xxix, 1–107, pls 32–60, 61–62, A–E. https://doi.org/10.5962/bhl.title.10706
Smith, T.E., Smith, C.J. & Nii Yemog Annang, T. (2015) Taxonomic catalogue of algae from Ghana (Africa) and new additions. Algae Press, Ave Maria, Florida, 101 pp.
Taylor, J.C. & Cocquyt, C. (2016) Diatoms from the Congo and Zambezi Basins – Methodologies and identification of the genera. ABC Taxa 16: 1–353.
Thwaites, G.H.K. (1848) Further observations on the Diatomaceae with descriptions of new genera and species. Annals and Magazine of Natural History, Series 2 1: 161–172, pls XI, XII. https://doi.org/10.1080/03745485809496091
UNESCO (2015) Rapport sur l’état de conservation des lacs d’Ounianga. Available from: https://whc.unesco.org/fr/list/1400/ (accessed 10 August 2022)
Van der Meeren, T., Deschamps, P., Sylvestre, F., Kemkong, V., Abderamane, M., Schuster, M. & Verschuren, D. (2019) Les lacs d’Ounianga: mieux comprendre leur dynamique hydrologique et écologique à long terme à travers l’’étude intégrée de leurs archives sédimentaires et de la limnologie et l’écologie aquatique actuelles. In: Raimond, C., Sylvestre, F., Zakinet, D. & Abderamane, M. (Eds.) Le Tchad des Lacs. Collection Synthèse IRD, pp. 127–138.
Van der Meeren, T., Verschuren, D., Sylvestre, F., Nassour, Y.A., Naudts, E.L., Aguilar Ortiz, L.E., Deschamps, P., Tachikawa, K., Bard, E., Schuster, M., Abderamane, M. (2022) A predominantly tropical influence on late Holocene hydroclimate variation in the hyperarid central Sahara. Science Advances 8 (14): eabk1261. https://doi.org/10.1126/sciadv.abk1261
Van Heurck, H. (1881) Synopsis des Diatomées de Belgique Atlas. Ducaju et Cie, Anvers. pls XXXI–LXXVII.