New records and species of Verosphacela (Onslowiales, Phaeophyceae): Verosphacela ebrachia from Greece, Verosphacela henryi sp. nov. from Rapa Nui and Verosphacela asensii sp. nov. from Ascension Island

Abstract Onslowiales are minute sublittoral marine brown algae found in warm-temperate to tropical regions of the North Atlantic Ocean. Sequences of the plastid-encoded markers psa A, psb C, rbc L and the Rubisco spacer of a strain of Verosphacela from Greece, previously identified as Verosphacela silvae , were highly similar to sequences of Verosphacela ebrachia from Florida, extending the distribution of the species to the Mediterranean and suggesting re-examination of the morphologically similar V. silvae described from Italy. Two other species were grown from substratum collected in the subtidal of Rapa Nui (Easter Island, subtropical Southeast Pacific) and Ascension Island (tropical Atlantic). According to sequences of the aforementioned markers, they also belong to the Onslowiales, forming a clade with V. ebrachia . They are described here as Verosphacela henryi sp. nov. and Verosphacela asensii sp. nov., respectively. In culture, they consisted of creeping branched filaments growing by means of an apical cell, and subterminal filament cells dividing once longitudinally. V. henryi formed four- to five-celled propagules without apical cells, resembling those of V. ebrachia , whereas V. asensii remained vegetative. V. asensii extends the distribution of the Onslowiales to the central tropical Atlantic, and V. henryi is the first record of the order in the Pacific Ocean.

Kimelfe