Marine unarmored dinoflagellates in the family Kareniaceae are known to possess chloroplasts of haptophyte origin, which contain fucoxanthin and its derivatives as major carotenoids, and lack peridinin. In the present study, the first species with the peridinin-type chloroplast in this family, Gertia stigmatica gen. et sp. nov., is described on the basis of ultrastructure, photosynthetic pigment composition, and molecular phylogeny inferred from nucleus- and chloroplast-encoded genes. Cells of G. stigmatica were small and harboring a chloroplast with an eyespot and two pyrenoids. The apical structure complex was straight, similar to Karenia and Karlodinium. Under transmission electron microscopy, the chloroplast was surrounded by two membranes, and the eyespot was composed of a single layer of osmiophilic globules (eyespot type A); this was never previously reported from the Kareniaceae. High performance liquid chromatography demonstrated the chloroplast contains peridinin, and neither fucoxanthin nor 19′-acyloxyfucoxanthins was identified. A phylogeny based on nucleus-encoded rDNAs suggested a position of G. stigmatica in the Kareniaceae, but not clustered within the previously described genera, i.e., Karenia, Karlodinium and Takayama. A phylogeny of chloroplast-encoded psbA, psbC and psbD indicated the chloroplast is of peridinin-type typical of dinoflagellates, but the most related species remains unclear.

已知Kareniaceae科的海洋无甲藻鞭毛藻具有触生植物来源的叶绿体，其中含有岩藻黄质及其衍生物作为主要类胡萝卜素，并且缺乏peridinin。在本研究中，该家族的第一个具有peridinin型叶绿体的物种为Gertia stigmatica gen。等。nov。是根据细胞核和叶绿体编码基因推断出的超微结构，光合色素成分和分子系统发育描述的。G. stigmatica的细胞很小，带有一个带有眼点和两个类胡萝卜素的叶绿体。根尖结构复杂，直，类似于卡列尼亚和卡洛丁。在透射电镜下，叶绿体被两层膜包围，并且眼点由单层渗透性小球组成（眼点类型A）；Kareniaceae以前从未报道过这一点。高效液相色谱法表明叶绿体中含有peridinin，并且未鉴定出岩藻黄质和19'-酰氧基岩藻黄质。基于核编码rDNAs甲系统发育建议的位置G. stigmatica在Kareniaceae，但前面描述的属，即，内未被聚类米氏，Karlodinium和高山。叶绿体编码的psbA，psbC和psbD的系统发育 表明叶绿体是鞭毛藻典型的peridinin型，但最相关的物种仍不清楚。