Research
| Title： | Flexiramia flexilis gen. et sp. nov. (Chlamydomonadales, Chlorophyta), a novel epilithic green alga from a subtropical river in China |
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| First author： | Lan, Qiumei; Dai, Qingyu; Zhu, Huan; Liu, Guoxiang; Liu, Benwen |
| Journal： | EUROPEAN JOURNAL OF PHYCOLOGY |
| Years： | 2025 |
| DOI： | 10.1080/09670262.2025.2567339 |
| Abstract： | Flexiramia flexilis gen. et sp. nov. a new epilithic and rheophilic (fast-flowing water adapted) chlorophyte from subtropical Chinese rivers, is proposed based on integrative morphology, ultrastructure, and molecular phylogeny (18S rDNA, ITS2, tufA). Phylogenetic analyses robustly place this taxon within the Stephanosphaerinia clade (Chlamydomonadales), forming a sister lineage to Spongiosarcinopsis. The alga exhibits: (1) irregularly curved and branched filaments with cell walls continuous along the main axis, without any septation, (2) a parietal chloroplast containing a pyrenoid with tubular invaginations and (3) asexual reproduction via biflagellate zoospores showing unidirectional germination. Flexiramia differs from Spongiosarcinopsis and other related genera by its filamentous growth (vs. unicellular/sarcinoid), tubular pyrenoid invaginations (vs. penetrated by straight/curved thylakoids) and rheophilic adaptation (vs. terrestrial/planktonic habitats). This discovery expands the known ecological and morphological diversity of the Stephanosphaerinia clade, revealing evolutionary transitions towards filamentous growth and specialized pyrenoid ultrastructure in freshwater chlorophytes. |
