Denticula iranica sp. nov. (Bacillariophyta), a new diatom species from Jolfa travertine depositing hot spring, northwestern Iran

Abstract

During limnological studies in the northwestern Iran, an unknown taxon belong to genus Denticula was found in Jolfa travertine depositing hot spring. The taxon has similarities with D. eximia, D. valida, D. subtilis, D. elegans, D. thermalis and D. thermaloides as shown by LM and SEM observations but based on detailed light (LM) and scanning electron microscopy (SEM) the species showed sufficient morphological differences to separate it as a new species. The new taxon Denticula iranica sp. nov. with valve length 7.0–38.5, valve width 3.0–6.5 and striae density is 32–34. Valves linear-lanceolate with acutely rounded ends. The keel is marginal along the edge of valve face. The raphe is eccentric and supported by fibulae that extend transapically from the center of the valve. Fibulae extend internally at irregular angles from the raphe to about halfway across the valve face. Striae are rarely visible under LM. Costae are typically parallel to one another, measuring in 8–9 in 10 µm. The new taxon has only been found on travertine-depositing hot spring where it occurs in alkaline lakes (pH = 9.8) with high specific conductance values (EC = 17.44 mScm− 1).