Two new species of Pyramimonas (Pyramimonadophyceae, Chlorophyta) associated with the subgenus Trichocystis from coral lagoons of the Ryukyu Archipelago, Japan

The characteristics of two new benthic species of Pyramimonas isolated from coral rubble have been determined. One, P. superba sp. nov., most similar to P. lunata, has a morphological character suite and molecular phylogenetic signal supporting it as a member of the subgenus Trichocystis, despite its uniqueness in producing mucilage. The other, P. lamellipunctata sp. nov., also shows phylogenetic affiliation with the subgenus Trichocystis using partial SSU data. However, this second species aligns with muciferous punctate species using rbcL data, although the clade is problematic as it includes the genus Pterosperma. Morphologically, cells of P. lamellipunctata share many features with muciferous punctate species but also exhibit important disparities with this group, most notably a lack of mucilage, suggesting that they form a unique lineage. HIGHLIGHTS ● Two new species of Pyramimonas are indicated as members of the subgenus Trichocystis using SSU data.● rbcL data only supports this association for one of the new species and affiliates the other with muciferous species of the subgenus Punctatae.● Morphological data only partially supports the second affiliation with punctate species, thereby inferring a unique lineage.