中国裸藻属新记录种的形态学和分子系统学研究

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

文章报道了采自中国上海市、黑龙江省和甘肃省的16株裸藻属物种,使用光学显微镜对其形态学特征进行了详细的观察,同时对所有藻株进行分离、纯化和培养,提取DNA后扩增各藻株的4个分子序列,并使用贝叶斯法和最大似然法构建系统发育树,结合形态学方法和分子生物学手段鉴定为9个中国裸藻属新记录种,分别为敏捷裸藻Euglena agilis、裸脊裸藻E.gymnodinoides、耶氏裸藻E.jirovecii、曼克斯裸藻E.mainxii、后缩裸藻E.retronata、光明裸藻E.splendens、星形裸藻E.stellata、拟星形裸藻E.pseudostellata和波形裸藻E.undulata,对所有物种的形态学特征进行了详细的描述,同时明确了各物种的系统发育位置。这些物种均是首次在中国发现,中国裸藻属新记录种的发现将对裸藻属单系性研究及中国绿色裸藻类生物多样性组成研究提供数据支撑。

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.