Pinnularia aljustrelica sp. nov. (Bacillariophyceae), a new diatom species found in acidic waters in the Aljustrel mining area (Portugal) and further observations on the taxonomy and ecology of P. acidophila Hofmann et Krammer and P. acoricola Hustedt

Abstract

A new benthic freshwater diatom species belonging to the genus Pinnularia Ehrenb. has been recorded in the Água Forte stream surrounding the Aljustrel mining area in southern Portugal. Pinnularia aljustrelica Luís, Almeida et Ector sp. nov. is described as a new species based on light and scanning electron microscopy observations and on its particular habitat in an acidic environment due to acid mine drainage, high metal concentrations (As, Cd, Cu, Fe, Mn, Pb and Zn) and high sulphate and conductivity. The taxa most similar to P. aljustrelica are P. acidophila Hofmann et Krammer, P. acoricola Hustedt and P. acoricola var. lanceolata Hustedt, so type materials of these taxa were studied for comparative purposes. Although, the ecology of the three similar taxa is also quite similar, the new species has a combination of particular morphological characteristics studied under LM and SEM that separates it from the rest. Pinnularia aljustrelica has a general shape relatively similar to P. acidophila and P. acoricola, but the valve outline is not as linear as in P. acidophila and not as oval as in P. acoricola.