Department of Biosciences, University of Salzburg, 5020, Salzburg, Austria.
J Eukaryot Microbiol. 2019 Sep;66(5):802-820. doi: 10.1111/jeu.12728. Epub 2019 Apr 15.
Tintinnid ciliates have traditionally been described and classified exclusively based on their lorica features. Although information on the cell characters is urgently needed for a natural classification, more molecular than cytological data has been accumulated over recent years. Apparently, the tintinnids developed in the marine environment and entered freshwater several times independently. Typical freshwater tintinnids belong to the genera Tintinnidium and Membranicola. The species are comparatively well-known regarding their morphology and characterised by two unusual de novo originating ciliary rows, the ventral organelles. In contrast, the cell features in the marine/brackish Tintinnidium species, specifically their somatic ciliary patterns, are insufficiently known or not known at all. Therefore, the morphology of a common marine/brackish representative, Tintinnidium mucicola, is redescribed based on live observation and protargol-stained material. Furthermore, biogeographical and autecological data of the species are compiled from literature and own records. The phylogenetic relationships of T. mucicola are inferred and the diversity of the family Tintinnidiidae is assessed from 18S rDNA sequences. The study shows that T. mucicola is not only molecularly distinct, but also characterised by many plesiomorphic features, for instance, it does not possess a verifiable homologue to the ventral organelles. Hence, a new genus, Antetintinnidium nov. gen., is established for T. mucicola. The new insights into the diversity of Tintinnidiidae shed light on the early evolution of tintinnids and might provide clues on their adaptions to freshwater.
纤毛虫一直以来都是根据它们的鞘壳特征来进行描述和分类的。尽管对于自然分类来说，细胞特征的信息是急需的，但近年来积累的更多的是分子数据而不是细胞学数据。显然，纤毛虫是在海洋环境中发展起来的，并多次独立进入淡水环境。典型的淡水纤毛虫属于纤毛属（Tintinnidium）和膜质体属（Membranicola）。这些物种在形态学方面相对比较知名，其特征是具有两个不寻常的从头起源的纤毛列，即腹器。相比之下，海洋/半咸水纤毛虫种的细胞特征，特别是其体细胞纤毛模式，知之甚少或根本不为人知。因此，基于活体观察和蛋白银染色材料，对一种常见的海洋/半咸水代表种——黏液纤毛虫（Tintinnidium mucicola）的形态进行了重新描述。此外，还从文献和自身记录中收集了该物种的生物地理和自生态数据。推断了 T. mucicola 的系统发育关系，并从 18S rDNA 序列评估了纤毛科的多样性。研究表明，T. mucicola 不仅在分子上是独特的，而且还具有许多原始特征，例如，它没有可验证的腹器同源物。因此，为 T. mucicola 建立了一个新属，Antetintinnidium nov. gen.。对纤毛科多样性的新认识揭示了纤毛虫的早期进化，并可能为它们适应淡水提供线索。
