A New Species from the Canary Islands Increases the Diversity of the Red Algal Genus Pterocladiella in the Northeastern Atlantic.

Abstract

Environmental and human factors are inducing a drastic decline in many marine algae in regions with a high floristic richness as in the Canary Islands. Simultaneously, undescribed algal species continue to be discovered, suggesting a probable loss in diversity, before being properly identified and catalogued. Turf-forming Gelidiales occur in marine littoral communities from tropical to warm temperate regions and are challenging to identify correctly because of their small size and simple morphology. In the present study, we combined morphological and molecular phylogenetics methods to study a turf-forming species of the genus Pterocladiella from the Canary Islands (NE Atlantic). Both cox1 and rbcL gene analyses revealed a novel species described here, Pterocladiella canariensis sp. nov. The new species has no single unique morphological feature, but it is different by a distinctive combination of attributes, namely, minute size less than 18 mm in height, ribbon-like erect axes, small polygonal cortical cells, cystocarp circular in outline with placental tissue attached to the floor, spermatangial sori with sterile margins with spermatangia simultaneously formed on both sides of the blade, and tetrasporangia arranged in V-shaped rows. Phylogenies inferred from cox1 and concatenated genes (cox1 + rbcL) suggest a link to only two Pterocladiella species endemic to South Africa and Madagascar; nevertheless, the rbcL gene establishes P. canariensis as the earliest divergent lineage of the genus