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Type: Article
Published: 2022-09-30
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Descriptions of three new diatom species in the genus Eunotia (Eunotiaceae, Bacillariophyta) from the Eocene Arctic

Connecticut College, Botany Department, New London, CT, U.S.A. 06320
Connecticut College, Botany Department, New London, CT, U.S.A. 06320
Connecticut College, Botany Department, New London, CT, U.S.A. 06320
acidic ecology freshwater Giraffe Pipe new species raphe Algae

Abstract

Eunotia is the largest and most diverse genus within the family Eunotiaceae, a primarily freshwater group of diatoms often found in dilute, acidic and humic-stained environments. Species in this genus are characterized by being asymmetric along their apical axis, symmetric about the transapical axis, and with a simple and reduced raphe system situated largely on the mantle and restricted to the apical ends of the valve. In addition, Eunotia taxa have one or more rimoportula per valve, usually close to the apex. Because of their reduced raphe system, coupled with the presence of rimoportulae, Eunotia and its relatives are often viewed as the oldest lineage of raphe-bearing diatoms. To date, the oldest remains of Eunotia species have been reported from the early to middle Eocene, including from the Giraffe Pipe locality, an ancient Eocene fossil site located in northern Canada near the Arctic Circle. Rocks from this site contain a large and diverse assemblage of Eunotia taxa. The purpose of this study is to begin to characterize this assemblage with descriptions of three new species, Eunotia giraffensis sp. nov., E. petasum sp. nov. and E. pseudonaegelii sp. nov. The new species, representing the longest specimens found at the Giraffe Pipe locality, each possess characteristics common to Eunotia making them easily assigned to this genus. Because the Eunotia lineage was well established by the early part of the Eocene, it is likely to be significantly older.

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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Siver, P.A., Hamilton, P.B., Stachura-Suchoples, K. &amp; Kociolek, J.P. (2005) Diatoms of North America: The Freshwater Flora of Cape Cod<em>. Iconographia Diatomologica</em> 14: 1–463.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Siver, P.A., Wolfe, A.P. &amp; Edlund, M. (2010) Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera <em>Oxyneis</em>, <em>Actinella</em> and <em>Nupela </em>(Bacillariophyceae). <em>Plant Ecology &amp; Evolution</em> 143: 340–351. https://dx.doi.org/10.5091/plecevo.2010.419</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Siver, P.A., Jo, B.Y., Kim, J.I., Shin, W., Lott, A.M. &amp; Wolfe, A.P. (2015) Assessing the evolutionary history of the class Synurophyceae (Heterokonta) using molecular, morphometric, and paleobiological approaches. <em>American Journal of Botany</em> 102: 1–21. https://doi.org/10.3732/ajb.1500004</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Siver, P.A., Velez, M., Cliveti, M. &amp; Binda, P. (2018) Early freshwater diatoms from the Upper Cretaceous Battle Formation in western Canada. <em>Palaios</em> 33: 1–10. https://doi.org/10.2110/palo.2018.045</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Siver, P.A., Lott, A.M. &amp; Torres, P. (2020) Abundance and distribution of testate amoebae bearing siliceous plates in freshwater lakes and ponds along the east coast of North America: Importance of water depth and pH. <em>Freshwater Science</em> 39: 791–803.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sorhannus, U. (2004) Diatom phylogenetics inferred based on direct optimization of nuclear-encoded SSU r-RNA sequences. <em>Cladistics</em> 20: 487–497. https://doi.org/10.1111/j.1096-0031.2004.00034.x</span></span></span></p>
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Werum, M. &amp; Lange-Bertalot, H. (2004) Diatoms in springs from Central Europe and elsewhere under the influence of hydrologeology and anthropogenic impacts. <em>Iconographia Diatomologica</em> 13: 3–417.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Wetzel, C.E., Ector, L., Hoffmann, L., Lange-Bertalot, H. &amp; Bicudo, D.C. (2011) Two new periphytic <em>Eunotia</em> species from the neotropical Amazonian “black waters”, with a type analysis of <em>E</em>. <em>braunii</em>. <em>Diatom Research</em> 26: 135–146. https://dx.doi.org/10.1080/0269249X.2011.587644</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Williams, D.W. &amp; Reid, G. (2006) Fossils and the tropics, the Eunotiaceae (Bacillariophyta) expanded: a new genus for the Upper Eocene fossil diatom <em>Eunotia</em> <em>reedii</em> and the recent tropical marine diatom <em>Amphora</em> <em>reichardtiana. European Journal of Phycology</em> 41: 147–154. https://doi.org/10.1080/09670260600628564</span></span></span></p>
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<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Zanon, V. (1929) Diatomee triassiche. <em>Atti Academie Nuovi Lincei, Roma</em> 14: 289–307.</span></span></span></p>