棕囊藻属(Phaeocystis)的分类与生活史(综述)

棕囊藻属Phaeocystis（定鞭藻纲Prymnesiophyceae)的分类问题目前还有争论。其种的分类标准是以初始的群体形态、地理分布、细胞特征等以及分子生物学特征，如染色体倍性，基因组大小等为依据。基于以上各种分类特征，目前比较确定的棕囊藻属藻类有四种：一种是只观察到单细胞形态的凹孔棕囊藻（P.scrobiculata)，另外三种是能够形成群体的波切棕囊藻（P.pouchetii)、球形棕囊藻（P.globosa)和南极棕囊藻（P.antarctica)。棕囊藻具有一个复杂的异形生活史，介于几种游离的单细胞（不动的细胞，具有鞭毛的动细胞，小游动孢子以及可能存在的大游动孢子）和群体之间的形态交替。但其生活史中仍有许多不确定的问题。

TAXONOMY AND LIFECYCLE OF GENUS PHAEOCYSTIS (PRYMNESIOPHYCEAE)

Studies of the genus Phaeocystis, a most widespread marine Prymnesiophyceae, are reviewed. The taxonomy of this genus remains unclear so far. Taxonomic criteria of species are based on initial colony shapes, geographic distribution, free-living cell characteristics as well as chemical products, ploidy, genome size, 18rRNA and so on. Based on all of these taxonomic characters, Phaeocystis has been divided into four definite species at present: P. scrobiculata, P. antarctica, P. globosa and P. pouchetii. The first has only free-living cells and forming no colony, while the rest are of colony-forming species with not only single cell but also colonies composed of thousands of cells embedded in one mucilaginous matrix occasionally reached several mm in diameter. Phaeocystis has a complex heteromorphic life Cycle exhibiting alternation between two different morphological forms: free-living cells and colonies. The unicellular stage involves several types: non-motile, flagellates, microzoospores and possibly macrozoospores. However, their respective functionwithin Phaeocystis life cycle and, in particular, their involvement in colony formation are not completely understood.