New phagotrophic euglenoid species from marine surface waters and the deep sea were isolated and described by light and scanning electron microscopy and 18S rDNA sequencing: Keelungia nitschei, Petalomonas acorensis and Ploeotia costaversata. The morphological characteristics of Keelungia nitschei agree with Keelungia pulex besides the slightly truncated anterior front of the cell of our strain. Phylogenetic analysis indicated low sequence similarity between K. nitschei and K. pulex (87.3%). Ploeotia costaversata clustered within the Ploeotia costata clade with a sequence similarity of 96.1% to P. costata strain Tam. Ultrastructural characteristics of our strain revealed helically twisted strips towards both poles of the protoplast. 18S rDNA phylogenies showed that Petalomonas acorensis is related to the clade of Petalomonas cantuscygni/Scytomonas saepesedens with the highest sequence similarity of 81.2% to P. cantuscygni. Six pellicle strips are visible, while two of them reach only the middle of the cell and four (two longitudinal, two helically twisted) join at the posterior front of the cell. Pressure experiments showed that the deep-sea strain K. nitschei was better adapted to high hydrostatic pressures (up to 500 bar) at 4 °C than the two surface water strains. All three strains increased the database (18S rDNA) of the underrepresented group of phagotrophic euglenids.

通过光学和扫描电子显微镜以及18S rDNA测序分离并描述了来自海洋表层水和深海的新吞噬营养类鳗鱼物种：Keelungia nitschei，Petalomonas acorensis和Ploeotia costaversata。除了我们菌株细胞的前部前部略微截断外，Knitlunia nitschei的形态特征与Keelungia pulex一致。系统发育分析表明，nitschei和K. pulex之间的序列相似性较低（87.3％）。丛生百日草（Ploeotia costaversata）聚集在丛生百日草（Ploeotia costata）进化枝中，与序列的相似度为96.1％P.costata菌株Tam。我们菌株的超微结构特征显示出螺旋扭曲的条带朝向原生质体的两个极点。18S rDNA的系统发育表明Petalomonas acorensis涉及的进化枝Petalomonas cantuscygni / Scytomonas saepesedens具有81.2％的最高序列相似P. cantuscygni。可以看到六个防护膜条，其中两个仅到达细胞的中央，而四个（两个纵向，两个螺旋扭曲）在细胞的后部接合。压力实验表明，深海菌株尼氏克氏菌比两个表面水应变更好地适应了4°C时的高静水压力（最高500 bar）。所有这三种菌株都增加了吞噬营养的鳗鱼的代表性数据库的数据库（18S rDNA）。