Recent studies suggested that the diversity of microbial eukaryotes in hypersaline environments is widely underestimated. Placidids are a group of heterotrophic stramenopile flagellates that are frequently found in these environments, but up to now only very few species were isolated and fully described, mostly from marine or brackish water sites. In this study, we extend the known diversity of Placididea by three new genera (Allegra, Haloplacidia, and Placilonga) compromising nine new species, isolated from athalassic, mostly hypersaline environments (Allegra dunaii, Allegra atacamiensis, Allegra hypersalina, Haloplacidia cosmopolita, Suigetsumonas keniensis) and marine waters (Placilonga atlantica, Placidia azorensis, Placidia abyssalis, Wobblia pacifica) including a description of their morphology and molecular phylogeny. In total, 36 strains were comparatively analysed. Studies from athalassic waters revealed an especially high number of different genotypes. A multigene analysis based on a ten genes dataset revealed a clear separation into marine, athalassic and brackish water clades. Several representatives were found to cope with hypersaline conditions from 20 to 250 PSU, even up to 284 PSU, suggesting that they may form a halotolerant group.

最近的研究表明，人们普遍低估了高盐环境中微生物真核生物的多样性。Placidids 是一组在这些环境中经常发现的异养原生藻鞭毛虫，但到目前为止，只有很少的物种被分离出来并得到充分描述，主要来自海洋或咸水地点。在这项研究中，我们通过三个新属（Allegra、Haloplacidia和Placilonga）扩展了 Placididea 的已知多样性，这些新属包括九个新物种，这些新物种是从主要高盐环境（Allegra dunaii、Allegra atacamiensis、Allegra hypersalina、Haloplacidia cosmopoligasta) 和海水 ( Placilonga atlantica , Placidia azorensis , Placidia abyssalis, Wobblia pacifica ) 包括对它们的形态和分子系统发育的描述。总共对36个菌株进行了比较分析。对浅海水域的研究揭示了特别多的不同基因型。基于十个基因数据集的多基因分析揭示了海洋、海洋和咸水进化枝的明显分离。发现几个代表可以应对 20 到 250 PSU，甚至高达 284 PSU 的高盐度条件，这表明它们可能形成一个耐盐组。