Pinnularia baetica sp. nov. (Bacillarophyceae): a new diatom species found in an alkaline mountain lagoon in the south of Europe (Granada, Spain)

A new benthic freshwater diatom species belonging to the genus Pinnularia was found in Laguna Seca of Sierra Seca in the north of the province of Granada, Spain. Pinnularia baetica sp.nov. is proposed as a new species based on observations under light (LM) and scanning electron microscopy (SEM) and its special ecology typical of a calcareous lagoon. The most similar taxa to P. baetica is P. atlasii and with more differences P. infirma and the last two were studied through material obtained in lagoons of northern Morocco. Although there are similarities in the morphological characters of the frustule, it was possible to verify through LM and SEM micrographs, evident differences between P. baetica and the other two taxa; on the one end, P. baetica has a panduriform shape more pronounced than P. infirma and bigger size. On the other hand, the absence of spines in P. baetica and the more convergent striation at the poles are the main differences with P. atlasi.