Species delimitation of Planosiphon gracilis morphospecies (Scytosiphonaceae, Phaeophyceae) from Japan and the description of Pl. nakamurae sp. nov.

HOSHINO, MASAKAZU; CROCE, MARIA EMILIA; KOGAME, KAZUHIRO; HANYUDA, TAKEAKI

PHYCOLOGIA

INT PHYCOLOGICAL SOC

Año: 2020

0031-8884

Molecular phylogenetic analyses based on mitochondrial cox1 and cox3 and chloroplast rbcL gene sequences revealed that the morphospecies of the brown alga Planosiphon gracilis (Scytosiphonaceae, Ectocarpales) from Japan is a complex of three distinct lineages (lineages I?III). Specimens from these lineages had the typical morphology of Pl. gracilis (i.e. flattened, linear, hollow, and gregarious erect thalli); thus, morphological discrimination among them was difficult in many cases. We observed large genetic divergences among the three lineages (c. 10% in cox1 and cox3). Moreover, we observed a reproductive isolating barrier between lineages I and II, despite the wide overlap in their geographic distribution. Our data, therefore, suggest that these three lineages are distinct species. Since lineage I included the holotype specimen of Pl. gracilis, this lineage was attributed to Pl. gracilis. Lineage III was phylogenetically close to Pl. complanatus from Canada with a 4.1% divergence in cox1. For lineage II, a new species name, Pl. nakamurae sp. nov., was proposed. This new species was also found in Argentina.