New species <i>Chara oryzae</i> and a new section <i>Corillionia</i> of <i>Chara</i> (Charales, Charophyceae) from European Mediterranean rice fields

European paddy fields harbour a morphologically and genetically unusual charophyte that is distant from any other European species. The new species, <i>Chara oryzae</i> from Mediterranean rice fields, was described using an integrated approach, including scanning electron microscopy and molecular phylogenetics. The combination of monoecy, a triplostichous stem cortex with solitary spine cells, haplostephanous stipulodes, abbreviated branchlet segments with their mostly incomplete diplostichous cortication, and long undifferentiated part of a branchlet distinguish <i>C. oryzae</i> from other <i>Chara</i> species described to date. A unique set of phenotypic characteristics and lack of affinity to <i>Chara</i> sections and subsections prompted us to accommodate the species in a new section <i>Corillionia</i> of the subgenus <i>Chara. C. oryzae</i> could be recognized as a species non-native to Europe because it is known only in rice fields, which have been maintained for centuries in the region studied. HIGHLIGHTS • European paddy fields harbour a charophyte with unusual morphology and genotype distant from any European species.• A new species, <i>Chara oryzae</i>, is described using an integrated approach.• A new section, <i>Corillionia</i>, of the subgenus <i>Chara</i> is proposed.