Epilithic diatoms of springs and spring–fed streams in Majorca Island (Spain) with the description of a new diatom species Cymbopleura margalefii sp. nov.

Abstract

The Island of Majorca (Spain) is characterized by a Mediterranean climate and a karstic geology that favors the formation of numerous springs and spring-fed streams on the island's Northwester zone. Water and epilithic diatom samples were collected from two springs and four spring-fed streams, located at altitudes ranging from 0 to 756 m a.s.l., in different seasons between 2005 and 2008. Water chemistry in these systems is characterized by high concentrations of dissolved calcium and pH values ranging from 6.6 to 8.4. A total of 111 diatom taxa belonging to 40 genera were found and the most abundant taxa were illustrated with LM and SEM. The diatom communities of the studied sites were dominated by species such as Achnanthidium minutissimum, A. pyrenaicum, Amphora pediculus, Cymbella vulgata, Diploneis separanda, Encyonopsis minuta, Gomphonema lateripunctatum and Navicula cryptotenella, reflecting the calcareous geological nature of Majorca Island. In the framework of the study 22 diatom taxa, which are new for Balearic Islands were recorded, such as Achnanthidium straubianum, Amphora indistincta, Cymbella lange-bertalotii, Encyonopsis subminuta, Karayevia kolbei, Navicula aff. margalithii, N. reichardtiana and N. subalpina. In addition, a new freshwater diatom species belonging to the genus Cymbopleura, C. margalefii was found in the Torrente of Deià. Cymbopleura margalefii is described as a new species based on LM and SEM observations, and compared with similar taxa. A checklist of the 309 diatom taxa recorded so far from the Balearic Islands is also presented.