Kudryavtsev Alexander, Völcker Eckhard, Clauß Steffen, Pawlowski Jan
Department of Invertebrate Zoology, Faculty of Biology, Saint-Petersburg State University, Universitetskaya nab., 7/9 199034 Saint-Petersburg, Russia.
Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Universitetskaya nab., 1 199034 Saint-Petersburg, Russia.
Int J Syst Evol Microbiol. 2019 Jun;71(3). doi: 10.1099/ijsem.0.004737. Epub 2021 Mar 12.
The order Himatismenida (Amoebozoa, Discosea) comprises naked amoebae with an organic coat that is located on the dorsal surface of the cell. The phylogenetic relationships among deeply branching genera of the Himatismenida are unclear, as data on the species diversity of the himatismenid genera is largely restricted to the derived genus . Here, we describe two new amoeba species that branch at the base of the order Himatismenida, evidenced by SSU rRNA gene and multigene analyses. Among them, a freshwater species gen. nov., sp. nov. has a dorsal cell coat consisting of flat, oval scales. This species forms a clade at the base of the Himatismenida, and the previously described , its closest relative, is transferred into the new genus as comb. nov. Although the two species are barely distinguishable by their sequence data, they are clearly distinct in morphology. Using this data, we can report the first evidence of a dorsal cell coat consisting of scales outside of the genus . The other species has a marine origin and branches deeply, close to the root of the phylogenetic tree of Himatismenida. Based on the morphology of this amoeba, it should be described as sp. nov., a new species of the genus . Analyses of the phylogenetic relationships and the ultrastructure of the deeply branching himatismenids, together with several of the newly obtained gene sequences of and suggest that some elements of the dorsal cell coat of may be ancestral for Himatismenida and have been partly retained in various more derived species of this clade, in particular, . Although actin and gene data do not resolve the higher-level relationships in Himatismenida, they correspond to the grouping of species within most genera.
希马蒂斯目（变形虫门，盘状亚门）包括裸变形虫，其细胞背表面有一层有机包膜。希马蒂斯目深度分支属之间的系统发育关系尚不清楚，因为关于希马蒂斯目属物种多样性的数据在很大程度上仅限于衍生属。在这里，我们描述了两个新的变形虫物种，它们在希马蒂斯目基部形成分支，这由小亚基核糖体RNA（SSU rRNA）基因和多基因分析所证实。其中，一个淡水物种新属新种有一层由扁平椭圆形鳞片组成的细胞背包膜。该物种在希马蒂斯目基部形成一个分支，其最亲近的亲属，即先前描述的物种，被转移到新属，成为新组合。尽管这两个物种通过序列数据几乎无法区分，但它们在形态上明显不同。利用这些数据，我们可以报告在该属之外首次发现由鳞片组成的细胞背包膜的证据。另一个物种起源于海洋，分支很深，接近希马蒂斯目系统发育树的根部。根据这种变形虫的形态，它应被描述为新属的一个新物种新种。对深度分支的希马蒂斯目物种的系统发育关系和超微结构分析，以及新获得的几个物种和的基因序列表明，该物种背包膜的一些成分可能是希马蒂斯目的祖先成分，并在该分支的各种更多衍生物种中部分保留，特别是。尽管肌动蛋白和基因数据无法解决希马蒂斯目中的高级关系，但它们与大多数属内物种的分组相对应。
