engleski

Entomoneis species in the Adriatic Sea

The genus Entomoneis Ehrenberg includes mostly epipelic, brackish, marine or freshwater pennate diatoms. Structurally this genus possess complex frustules, characterized by bilobate raphe-bearing keel elevated from the valve body, the morphologically variable junction lines and numerous girdle bands. Most recognizable morphological features of these diatoms are 90°cell torsion around apical axis and slightly silicified frustules. Up to date, three different Entomoneis species have been recorded in the Adriatic Sea – E. alata, E. paludosa and E. pulchra and none of them has been cultivated and thoroughly analysed through morphological and molecular analysis. For purposes of this study several oceanographic cruises were conducted – BIOTA (Bio-tracing Adriatic water masses) expedition conducted in February/March 2015 and March 2016 in the south-eastern Adriatic Sea, and middle Adriatic cruises (Telašćica Nature Park and Kornati National Park) conducted during June and October 2015. During these cruises, numerous Entomoneis cells were harvested. Cells were manually isolated by micropipette and agar plating techniques and long-term cultured in Guillard's F2 marine enrichment solution. In 2015 BIOTA cruise the enigmatic taxon was found in the water samples in low abundances (up to 200 cells L-1) and three monoclonal strains were established from plankton net samples. After thorough morphological observations (light, scanning and transmission electron microscopy) and molecular analyses (SSU, rbcL, psbC gene phylogenies) from these cultivatedstrains we concluded they belong to a new Entomoneis species. The same molecular and taxonomical analyses on the strain isolated from middle Adriatic revealed yet another possible new species for science. On-going study on genus Entomoneis is promising and challenging for the phytoplankton in the Adriatic Sea and for diatom taxonomy in general.

diatoms ; Adriatic Sea ; phylogeny ; morphology

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