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

The characteristics of two new benthic species of <i>Pyramimonas</i> isolated from coral rubble have been determined. One, <i>P. superba</i> sp. nov., most similar to <i>P. lunata</i>, has a morphological character suite and molecular phylogenetic signal supporting it as a member of the subgenus <i>Trichocystis</i>, despite its uniqueness in producing mucilage. The other, <i>P. lamellipunctata</i> sp. nov., also shows phylogenetic affiliation with the subgenus <i>Trichocystis</i> using partial SSU data. However, this second species aligns with muciferous punctate species using <i>rbc</i>L data, although the clade is problematic as it includes the genus <i>Pterosperma</i>. Morphologically, cells of <i>P. lamellipunctata</i> 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 <i>Pyramimonas</i> are indicated as members of the subgenus <i>Trichocystis</i> using SSU data.● <i>rbc</i>L 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.