Two new species of diatoms (Bacillariophyceae) from the coast of Tenerife, the Canary Islands, Spain

In a study of epiphytic diatoms from the coasts of Tenerife, Canary Islands, two new species, Caloneis virgaestriata and Seminavis undulata, were discovered and analyzed using light and electron microscopy. Caloneis virgaestriata is characterized by its small size, areolae rows that expand to cover the virgae between striae, and distal raphe ends curved in opposite directions. This last feature is present in only one other species currently placed in the genus, C. hustedtii. Seminavis undulata exhibits a novel morphological trait not previously recorded in the genus: its external proximal raphe ends are located beneath a silica flap with a wavy margin, giving the appearance of undulating raphe ends. A comparison of S. undulata with the morphologically similar taxa S. delicatula and S. obtusiuscula suggests that the latter two may in fact be conspecific. Both new species were found growing epiphytically on the chlorophyte Cladophora prolifera (Roth) Ktzing collected from a sheltered tide pool. Detailed ultrastructural descriptions are provided, along with comparisons to morphologically similar species. The present work is the first report of new benthic diatom species described from the Canary Islands.