engleski

Hidden diversity of planktonic Entomoneis species

The genus Entomoneis Ehrenberg includes mostly epipelic, brackish, marine or freshwater pennate diatoms with structurally complex panduriform shaped frustules, characterized by bilobate raphe-bearing keel elevated from the valve body, morphologically variable junction lines and numerous girdle bands. Previous new species descriptions based only on morphological approach neglected the full diversity of diatom genus Entomoneis, which today becomes well-known from both benthos and plankton of world's freshwater and marine ecosystems. Since the recent description of new species combining both molecular and morphological characters – Entomoneis tenera Mejdandžić & Bosak, continued research on hidden diversity of Entomoneis species in the Adriatic Sea has been conducted. Samples in this study originate from BIOTA (Bio-tracing Adriatic Water Masses) cruise conducted in March 2016 in the south-eastern Adriatic Sea and middle Adriatic sampling campaigns (Telašćica Nature Park and Kornati National Park) conducted during June and October 2015. 14 monoclonal strains were established from plankton net samples and fractioned samples taken from range of different depths (30m, 100m, 250m) by manual pipette isolation and were further maintained in f/2 medium at stable conditions: temperature 18°C-19°C, light intensity of 30 μmol photons m–2 s–1 with photoperiod of 16h of light and 8h of dark. Combined molecular phylogeny based on three gene sequences (small subunit (SSU) rDNA, rbcL and psbC genes) of Adriatic Sea strains identified as Entomoneis sp. revealed the presence of several distinct lineages, likely corresponding to different species. Morphological separation of these lineages in light microscope proved to be extremely difficult, although some of the lineages were separated by cell sizes and preferences to frustule torsions. In electron microscope (SEM and TEM) we observed some discernable characters, such as presence of interfibulae in two lineages, differently shaped valvocopulae or density of perforations within striae od the valve or wing. Here, we present preliminary results on these small planktonic Entomoneis lineages, discussing their phylogenetic position and morphological characters in the context of the other species from the genus, confirming the monophyly of the genus within canal-raphe bearing diatoms.

Entomoneis ; planktonic diatoms ; cultured strains ; phylogeny ; morphology

nije evidentirano