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Ons Daly Yahia-Kéfi, Sami Souissi, Mario De Stefano, Mohamed Néjib Daly Yahia

Bellerochea horologicalis and Lithodesmioides polymorpha var. tunisiense var. nov. (Coscinodiscophyceae, Bacillariophyta) in the Bay of Tunis: ultrastructural observations and spatio-temporal distribution

Keywords: Bellerochea horologicalis, EM ultrastructure, Lithodesmioides polymorpha var. tunisiense, Mediterranean Sea, spatio-temporal distribution, Tunesia

Phytoplankton samples were taken along the Tunisian coasts and especially in the Bay of Tunis in the southwestern Mediterranean Sea. Here we report the ultrastructure and the spatio-temporal distribution of two new records for the diatom flora of the Mediterranean Sea: Bellerochea horologicalis and Lithodesmioides polymorpha var. tunisiense var. nov. The new variety can be distinguished from the nominate variety by such morphological features as valve shape, striae density on valve face and mantle, and fine structure of the areolae occlusions. Both diatom taxa are present year-round in the Bay of Tunis, but are most abundant in its southwestern region. They appear to be associated with waters characterised by high turbidity and high nutrient levels. In this region of the Bay of Tunis, both diatom taxa are presented alive in the sediment up to 14 cm deep. B. horologicalis is also present in the Bay of Sousse, whereas L. polymorpha var. tunisiense also occurs in the Gulf of Gabès.

Botanica Marina, Walter de Gruyter

Print ISSN: 0006-8055
Volume: 48, 01/2005
Pages: 58 - 72

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