Abstract:

Aim: The genus Desmodesmus is one of the most common green microalgae in freshwater ecosystems and serves as an important indicator of water quality monitoring and ecological assessment. Meanwhile, species of this genus are easily cultured and synthesize a variety of high-value metabolites, endowing them with broad application potential in bioenergy, food, feed, pharmaceuticals, and environmental remediation. However, the phylogenetic relationships among infrageneric groups remain poorly elucidated, and the taxonomic system of this genus in China is in urgent need of systematic revision. 

Methods: This study collected Desmodesmus samples from diverse regions across China, and integrated morphological observations with molecular marker amplification to reconstruct the phylogeny of the genus. At the same time, combining historical records and the latest advances in taxonomic research, a comprehensive revision of the species diversity of the genus Desmodesmus in China was conducted. 

Results: (1) Currently, 41 species and 4 varieties of the genus Desmodesmus recorded in China have been revised based on molecular data. Additionally, 26 species and 8 varieties and forms, although morphologically consistent with the characteristics of Desmodesmus, have not yet undergone revision and remain taxonomically classified within Scenedesmus. (2) The ITS1 and tufA markers were newly applied to reconstruct the phylogeny of the genus, identifying nine stable evolutionary clades for the first time and revealing the core morphotype of each clade. 

Conclusion: This study systematically clarified the species diversity and phylogenetic relationships of Desmodesmus in China, providing a fundamental taxonomic reference for aquatic biodiversity monitoring and ecosystem health assessment. It also established a taxonomic foundation for the resource development and industrial utilization of this genus.

Key words: Desmodesmus, phylogeny, molecular systematics, freshwater algae