Abstract
The diatom genus Fallacia includes species having a conopeum which is a perforated thin sheath of silica lying along the apical axis on the external valve face and a hyaline lateral area in the internal valve face. In surveying the benthic diatoms of Basra, a new small brackish water species, Fallacia fawensis was found associated with fine-grained substrata on the western bank of Shatt Al–Arab River, Southern Iraq. This epipelic species is described based on light and scanning electron microscopy and characterized by having a porous conopeum covering the area between raphe sterna and mantle, narrow elongated marginal striae, and a structure similar to lateral hyaline areas in the valve internal side. The terminal raphe endings on the external valve face, below valve apex, the raphe sternum inner margins come close to each other, blocking raphe canal but leaving a lacuna-like thin groove for connection with the deflected upper part of the open raphe canal. These features separated this species from allied taxa of the genus and also from closely related genera, Pseudofallacia and Germaniella. Notes on the ecology and distribution of the new species as well as the associated diatom taxa are provided.
References
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<p>Mohamed, A.R.M. & Abood, A.N. (2017) Ecological health assessment of the Shatt Al-Arab River. <em>IOSR Journal of Agriculture and Veterinary Science</em> 10: 1–8.</p>
<p>Procopiak, L.K. & Fernandes, L.F. (2003) Valve morphology of the benthic diatom <em>Fallacia</em> <em>marnieri</em> (Manguin) Witkowski (Sellaphoraceae-Bacillatiophyta). <em>Brazilian Journal of</em> <em>Biology</em> 63: 113–119. https://doi.org/10.1590/S1519-69842003000100015</p>
<p>Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. & Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell. <em>Nova</em> <em>Hedwigia</em> 64: 513–533.</p>
<p>Round, F.E., Crawford, R.M. & Mann, D.G. (1990) <em>The diatoms, Biology and Morphology</em> <em>of</em> <em>the Genera</em>. Cambridge University Press, Cambridge.</p>
<p>Sabbe, K., Vyverman, W. & Muylaert, K. (1999) New and little-known <em>Fallacia</em> species (Bacillariophyta) from brackish and marine intertidal sandy sediments in Northwest Europe and North America. <em>Phycologia</em> 38: 8–22. https://doi.org/10.2216/i0031-8884-38-1-8.1</p>
<p>Smith, W. (1856) <em>A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens</em>. Vol. 2. A-E. John van Voorst., London, pp. 1–107.</p>
<p>Stancheva, R. & Manoylov, K.M. (2018) <em>Fallacia californica</em> sp. nov. (Bacillariophyta), a new freshwater diatom species from streams in California, USA. <em>Phytotaxa</em> 345: 104–118. https://doi.org/10.11646/phytotaxa.345.2.2</p>
<p>Werum, M. & 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.</p>
<p>Witkowski, A. (1991) <em>Fallacia cassubiae</em> sp. nov., a new brackish-water diatom from the Puck Bay (Southern Baltic Sea), Poland. <em>Diatom Research</em> 6: 401–409. https://doi.org/10.1080/0269249X.1991.9705184</p>
<p>Witkowski, A. (1993) <em>Fallacia florinae</em> (Moeller) comb. nov. a marine, epipsammic diatom. <em>Diatom Research</em> 8: 215–219. https://doi.org/10.1080/0269249X.1993.9705254</p>
<p>Witkowski, A., Lange-Bertalot, H. & Metzeltin, D. (2000) <em>Diatom Flora of Marine Coasts</em> <em>I</em>.<em> In: </em>Lange-Bertalot, H. (Ed.) <em>Iconographia Diatomologica.</em> Vol. 7. Annotated Diatom Micrographs. Diversity-Taxonomy-Identification. Koeltz Scientific Books, Königstein, Germany, pp. 1–925.</p>
<p>Al-Handal, A.Y. (2009) Littoral diatoms from the Shatt Al-Arab estuary, North West Arabian Gulf. <em>Cryptogamie Algologie</em> 30: 153–183.</p>
<p>Al-Handal, A.Y. & Al-Shaheen, M.A. (2019) <em>Diatoms in the wetlands of Southern Iraq</em>. <em>Bibliotheca Diatomologica</em> 67: 1–241.</p>
<p>Al-Yamani, F.Y. & Saburova, M.A. (2011) <em>Illustrated guide on the benthic diatoms of Kuwait´s marine environment.</em> Institute for Scientific Research, Lucky Press, Kuwait, 352 pp.</p>
<p>Bory de Saint-Vincent, J.B.G.M. (1822) Bacillariées. <em>Dictionnaire Classique d’Histoire naturelle</em> 2: 127–129.</p>
<p>Garcia, M. (2003) Observations on the diatom genus <em>Fallacia</em> (Bacillariophyta) from southern Brazilian sandy beaches. <em>Nova Hedwigia</em> 77: 309–330. https://doi.org/10.1127/0029-5035/2003/0077-0309</p>
<p>Genkal, S.I. & Yarushina, M.I. (2017) The species of the genus <em>Fallacia</em> A.J. Stickle & D.G. Mann (Bacillariophyta) in Russia: morphology, taxonomy, ecology and distribution. <em>International Journal on Algae</em> 19: 99–110. https://doi.org/10.1615/InterJAlgae.v19.i2.10</p>
<p>Guiry, M.D. & Guiry, G.M. (2020) <em>AlgaeBase.</em> World-wide electronic publication, National University of Ireland, Galway. [https://www.algaebase.org]</p>
<p>Hantizsch, C.A. (1860) Neue Bacillarien: <em>Nitzschia vivax</em> var. <em>elongata</em>, <em>Cymatopleura</em> <em>nobilis</em>. <em>Hedwigia</em> 2: 1–40.</p>
<p>Hinton, G.C.F. & Maulood, B.K. (1980) Some diatoms from brackish water habitats in southern Iraq. <em>Nova Hedwigia</em> 31: 475–486.</p>
<p>Kützing, F.T. (1849) <em>Species Algarum</em>. F.A. Brockhaus, Leipzig 1 (6): 1–922.</p>
<p>Liu, Y., Kociolek, J.P., Fan, Y. & Wang, Q. (2012) <em>Pseudofallacia</em> gen. nov., a new freshwater diatom (Bacillariophyceae) genus based on <em>Navicula</em> <em>occulta</em> Krasske. <em>Phycologia</em> 51: 620–626. https://doi.org/10.2216/11-098.1</p>
<p>Li, Y., Suzuki, H., Nagumo, T. & Tanaka, J. (2014) Auxosporulation, morphology of vegetative cells and perizonium of <em>Fallacia tenera</em> (Hust.) D.G.Mann (Bacillariophyceae). <em>Phytotaxa</em> 164: 239–254. https://doi.org/10.11646/phytotaxa.164.4.3</p>
<p>Li, Y., Suzuki, H., Nagumo, T., Tanaka, J., Sun, Z. & Xu, K. (2015) <em>Fallacia decussata</em>, sp. nov. : a new marine benthic diatom (Bacillariophyceae) from Northeast Asia. <em>Phytotaxa</em> 224: 258–266. https://doi.org/10.11646/phytotaxa.224.3.4</p>
<p>Li, Y., Suzuki, H., Nagumo, T., Tanaka, J., Sun, Z. & Xu, K. (2019) Three new species of <em>Fallacia </em>from intertidal sediments in Japan. <em>Diatom Research</em> 3: 75–83. https://doi.org/10.1080/0269249X.2019.1606855</p>
<p>Maulood, B.K., Hinton, G.C.F., Whitton, B.A. & Al-Saady, H.A. (1981) On the algal ecology of the lowland Iraqi marshes. <em>Hydrobiologia</em> 80: 267–276. https://doi.org/10.1007/BF00018367</p>
<p>Metzeltin, D., Lange-Bertalot, H. & García-Rodriguez, F. (2005) <em>Diatoms of Uruguay Compared with other taxa from South America and elsewhere</em>. <em>Iconographia Diatomologica</em> 15: 1–736.</p>
<p>Mohamed, A.R.M. & Abood, A.N. (2017) Ecological health assessment of the Shatt Al-Arab River. <em>IOSR Journal of Agriculture and Veterinary Science</em> 10: 1–8.</p>
<p>Procopiak, L.K. & Fernandes, L.F. (2003) Valve morphology of the benthic diatom <em>Fallacia</em> <em>marnieri</em> (Manguin) Witkowski (Sellaphoraceae-Bacillatiophyta). <em>Brazilian Journal of</em> <em>Biology</em> 63: 113–119. https://doi.org/10.1590/S1519-69842003000100015</p>
<p>Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. & Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell. <em>Nova</em> <em>Hedwigia</em> 64: 513–533.</p>
<p>Round, F.E., Crawford, R.M. & Mann, D.G. (1990) <em>The diatoms, Biology and Morphology</em> <em>of</em> <em>the Genera</em>. Cambridge University Press, Cambridge.</p>
<p>Sabbe, K., Vyverman, W. & Muylaert, K. (1999) New and little-known <em>Fallacia</em> species (Bacillariophyta) from brackish and marine intertidal sandy sediments in Northwest Europe and North America. <em>Phycologia</em> 38: 8–22. https://doi.org/10.2216/i0031-8884-38-1-8.1</p>
<p>Smith, W. (1856) <em>A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens</em>. Vol. 2. A-E. John van Voorst., London, pp. 1–107.</p>
<p>Stancheva, R. & Manoylov, K.M. (2018) <em>Fallacia californica</em> sp. nov. (Bacillariophyta), a new freshwater diatom species from streams in California, USA. <em>Phytotaxa</em> 345: 104–118. https://doi.org/10.11646/phytotaxa.345.2.2</p>
<p>Werum, M. & 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.</p>
<p>Witkowski, A. (1991) <em>Fallacia cassubiae</em> sp. nov., a new brackish-water diatom from the Puck Bay (Southern Baltic Sea), Poland. <em>Diatom Research</em> 6: 401–409. https://doi.org/10.1080/0269249X.1991.9705184</p>
<p>Witkowski, A. (1993) <em>Fallacia florinae</em> (Moeller) comb. nov. a marine, epipsammic diatom. <em>Diatom Research</em> 8: 215–219. https://doi.org/10.1080/0269249X.1993.9705254</p>
<p>Witkowski, A., Lange-Bertalot, H. & Metzeltin, D. (2000) <em>Diatom Flora of Marine Coasts</em> <em>I</em>.<em> In: </em>Lange-Bertalot, H. (Ed.) <em>Iconographia Diatomologica.</em> Vol. 7. Annotated Diatom Micrographs. Diversity-Taxonomy-Identification. Koeltz Scientific Books, Königstein, Germany, pp. 1–925.</p>