海南岛海洋绿藻新记录种未氏仙掌藻(Halimeda velasquezii)的形态学与分子系统学分析

Morphological and molecular study on marine green alga,Halimeda velasquezii,first recorded in Hainan Island

2019年4月在海南岛冯家湾潮间带的野外调查过程中采集到一种仙掌藻,利用传统形态分类学与分子系统分类学结合的方法,将该种鉴定为未氏仙掌藻Halimeda velasquezii W.R.Taylor。该种的形态特征为藻体呈绿色钙化,直立生长,固着器单一较小,由横卵形或肾形节片连接形成,节片表面观形态为近圆形,内部为管状髓丝,节点处髓丝多发生侧面成对融合,皮层下髓丝末端无囊状膨大。1,5-二磷酸核酮羧化酶/氧化酶大亚基基因(ribulose-1,5-bisphosphate carboxylase/oxygenaselargesubunit,rbc L)的序列分析结果显示,在系统发育树上,本研究样本与印度洋-太平洋地区产的未氏仙掌藻处于同一分支,且自展支持值为100,碱基基因差异为9bp(0.69%)。该种在海南岛海域首次被发现,为新记录种。本研究同时首次提取并分析了中国种群的rbc L基因序列,丰富了该种的中国种群的生态学知识,扩展了其地理分布范围,对了解海南岛海域海藻资源的生物多样性及其分布特征具有重要意义。

Samples of Halimeda were collected from the intertidal zone of Fengjia Bay in Hainan Island during the field survey in April 2019.Detailed morphological structure observation and molecular systematics analysis were conducted.The results showed that the sample was identified as Halimeda velasquezii W.R.Taylor.We found the following combination of the characters:the thalli is green,calcified,erect from a single small stupose holdfast;segments are transversely oval to reniform linking together;utricles form in surface view is round or a little compressed;filaments inside are long tubular;medullary filaments fuse for a short distance in pairs in common;subcortical filaments loosely branch,and are not utriculiform.The rbc L gene analysis showed that the sample was clustered on the same branch as that from the Indian Ocean-Pacific Ocean region,whose bootstrap value and sequence divergence were 100 and 9 bp(0.69%),respectively.The species was the first recorded in Hainan Island.The results should enrich our knowledge of Chinese species’morphology and extend their geographical distribution.They should be of great significance to understand the biodiversity and distribution characteristics of algal resources in the waters of Hainan Island.