MORPHOLOGICAL AND MOLECULAR PHYLOGENETIC STUDIES ON NEW RECORD SPECIES OF EUGLENA IN CHINA

Euglena, a common group found in freshwater, belongs to the phylum Euglenophyta. Although E. viridis was observed by Leeuwenhoek as early as 1674, the genus was officially established by Ehrenberg in 1830. To date, 167 species of Euglena have been reported worldwide. Skvortzov conducted extensive surveys on Euglenoids (including Euglena) in China (especially in Northeast China) in the 1920s and 1930s. However, the most comprehensive study of Euglena species in China was documented in the book “Flora algarum sinicarum aquae dulcis Tomu Ⅵ Euglenophyta”, published in 1999, reporting a total of 62 Euglena species (with 12 species removed in foreign studies). Since then, studies on the classification of green Euglenoids in China have decreased, often mentioned within investigation of phytoplankton communities. In this study, 16 strains of Euglena species were collected and cultured from Shanghai, Heilongjiang and Gansu provinces. Morphological characteristics of all strains were meticulously observed using optical microscopy. Each strain was isolated, purified and cultured at the same time. Algal DNA was extracted, and four molecular sequences of each strain were amplified. Phylogenetic trees were constructed by using Bayesian method and maximum likelihood method. Employing both morphological and molecular biological methods, we identified nine species: E. agilis, E. gymnodinoides, E. jirovecii, E. mainxii, E. retronata, E. splendens, E. stellata, E. pseudostellata, E. Gymnodinoides, and E. undulata. The morphological characteristics of all species were described in detail, and the phylogenetic position of each species was defined. All of these species were discovered in China for the first time. Despite the abundance of fresh water resources in China, there has been a scarcity of taxonomic studies on Euglena species. This study provides morphological and molecular biological data on nine newly recorded species in China, yet there remain more species awaiting discovery. The exploration and discovery of Euglena species will provide support for the study of the Euglena monophyly and the biodiversity composition of green Euglenoids in China.