Diatom Species that Characterize Saline Ponds (Southern Spain) with the Description of a New Navicula Species

The southern Iberian Peninsula has a high number of saline ponds where electric conductivity (EC) is an important factor that directly affects the distribution and abundance of aquatic organisms. Environmental factors (such as pH, EC, and temperature) were measured, and diatom assemblages were sampled in 15 shallow saline ponds in southern Spain over a range of EC (1.4 mS to 51.6 mS cm−1). Three groups of ponds were defined based on EC (oligosaline 1.4 to 5.3 mScm−1, mesosaline 10.9 to 17.3 mScm−1, and eusaline 32.3 to 51.6 mScm−1), and sediment diatom assemblages were studied. PERMANOVA analysis revealed significant differences in diatom community composition between the three groups of ponds. Non-metric multi-dimensional scaling analysis (n-MDS) showed distinct clusters of diatom assemblages in oligosaline and mesosaline ponds. The dominant diatom species in the eusaline ponds were Tryblionella pararostrata (Lange-Bertalot) Clavero & Hernández-Mariné, Halamphora cf. pertusa J.G. Stepanek & Kociolek, Halamphora sp.1, and Cocconeis euglypta Ehrenberg; the mesosaline ponds were dominated by Navicula veneta Kützing, Nitzschia elegantula Grunow in Van Heurck, and Planothidium delicatulum (Kützing) Round & Bukhtiyarova; and the oligosaline ponds were dominated by Navicula veneta, Pseudostaurosira brevistriata (Grunow) D.M. Williams & Round, and Nitzschia inconspicua Grunow. A new diatom species was described from three eusaline ponds (32-51.6 mS cm−1). A detailed description of N. maiorpargemina sp. nov. is presented in this study based on light and scanning electron microscopy after comparison with morphologically and ecologically related taxa.