DNA barcoding of the German green supralittoral zone indicates the distribution and phenotypic plasticity of Blidingia species and reveals Blidingia cornuta sp. nov.

Abstract

In temperate and subarctic regions of the Northern Hemisphere, green algae of the genus Blidingia are a substantial and environment-shaping component of the upper and mid-supralittoral zones. However, taxonomic knowledge on these important green algae is still sparse. In the present study, the molecular diversity and distribution of Blidingia species in the German State of Schleswig-Holstein was examined for the first time, including Baltic Sea and Wadden Sea coasts and the off-shore island of Helgoland (Heligoland). In total, three entities were delimited by DNA barcoding, and their respective distributions were verified (in decreasing order of abundance: Blidingia marginata, Blidingia cornuta sp. nov. and Blidingia minima). Our molecular data revealed strong taxonomic discrepancies with historical species concepts, which were mainly based on morphological and ontogenetic characters. Using a combination of molecular, morphological and ontogenetic approaches, we were able to disentangle previous mis-identifications of B. minima and demonstrate that the distribution of B. minima is more restricted than expected within the examined area. Blidingia minima, the type of the genus name Blidingia, is epitypified within this study by material collected at the type locality Helgoland. In contrast with B. minima, B. marginata shows a higher phenotypic plasticity and is more widely distributed in the study area than previously assumed. The third entity, Blidingia cornuta sp. nov., is clearly delimited from other described Blidingia species, due to unique characters in its ontogenetic development and morphology as well as by its tufA and rbcL sequences.