The parasitic dinoflagellate Syltodinium listii was investigated from the open waters of the English Channel, southern North Sea and the NW Mediterranean Sea. Syltodinium listii has been unreported since its original description in the North Sea. Cells of S. listii were able to infect copepod eggs of different species, and even nauplii, and after each infection formed up to 32 cells embedded in a mucous envelope. Infection of the same host by more than one dinoflagellate was frequent; although overall, the progeny were reduced in number. Molecular phylogeny based on the small subunit ribosomal RNA (SSU rRNA) gene revealed that S. listii clusters with a group of environmental sequences from the cold North Atlantic region as a sister group of Gymnodinium aureolum. The large subunit ribosomal RNA (LSU rRNA) gene sequences of S. listii from the English Channel and cf. Gyrodinium undulans from the Mediterranean Sea were identical. Thus, we propose Syltodinium undulans comb. nov. for Gyrodinium undulans. The first internal transcribed spacer (ITS) and complete SSU rRNA gene sequences of Dissodinium pseudolunula are provided. The parasitic species of Chytriodinium, Dissodinium and Syltodinium cluster together within the family Chytriodiniaceae, including the free-living species Gymnodinium aureolum, G. corollarium and G. plasticum.

从英吉利海峡，北海南部和地中海西北部的开阔水域对寄生鞭毛藻Syltodinium listii进行了调查。Syltodinium listii自从它在北海的原始描述以来未曾报告过。链球菌的细胞能够感染不同物种的co足类卵，甚至无节幼体，并且在每次感染后最多形成嵌入粘膜包膜的32个细胞。同一宿主经常被超过一种鞭毛鞭毛虫感染；尽管总的来说，后代的数量有所减少。基于小亚基核糖体RNA（SSU rRNA）基因的分子系统发育揭示了链球菌由冷北大西洋地区的一群环境序列组成的金of属姐妹群。来自英吉利海峡的比氏链球菌的大亚基核糖体RNA（LSU rRNA）基因序列，参见 来自地中海的Gyrodinium undulans完全相同。因此，我们提出了Syltodinium undulans梳。十一月 为Undulans的Gyrodinium。提供了第一个内部转录间隔区（ITS）和假双歧的完整的SSU rRNA基因序列。梭菌属，二嘧啶类和Syltodinium的寄生种。家庭Chytriodiniaceae内聚集在一起，包括自由生活的物种裸甲藻aureolum，G. corollarium和G. plasticum。