Laboratory of Cellular and Molecular Protistology, Zoological Institute, Russian Academy of Sciences, 199034, Saint-Petersburg, Russia.
Department of Invertebrate Zoology, Faculty of Biology, Saint-Petersburg State University, 199034, Saint-Petersburg, Russia.
Sci Rep. 2022 Jul 22;12(1):12541. doi: 10.1038/s41598-022-16721-2.
Coronamoeba villafranca gen. nov. sp. nov. is a small amoeba isolated from the surface planktonic biotope in the Bay of Villefranche (Mediterranean Sea). It has a confusing set of morphological and molecular characters. Its locomotive form is subcylindrical and monopodial with monoaxial cytoplasmic flow and occasional hyaline bulging at the anterior edge (a monotactic morphotype). Based on this set of characters, this amoeba is most similar to members of the genus Nolandella (Tubulinea, Euamoebida). However, molecular phylogenetic analysis based on only the small subunit ribosomal RNA (SSU rRNA) gene and on two concatenated markers (SSU rRNA gene and actin) robustly places this species in the Discosea, specifically, in a clade with Dermamoeba and Paradermamoeba (Dermamoebida) as the closest described relatives, and several SSU rRNA clones from environmental DNA. A unique glycocalyx of the studied amoeba consisting of complex separate units with pentameric symmetry may be considered a unifying character of this species with other dermamoebids. The monotactic morphotype demonstrated by these amoebae primarily occurs in Tubulinea but was recently confirmed in other clades of Amoebozoa (e.g. Dactylopodida and Variosea). This morphotype may be the plesiomorphic mode of cell organization in Amoebozoa that might have evolved in the last amoebozoan common ancestor (LACA) and conserved in several lineages of this group. It may reflect basic characteristics of the cytoskeletal structure and functions in Amoebozoa.
冠盘形目科新目新种是从土伦湾（地中海）浮游生物表面生境中分离出的一种小型变形虫。它具有一组令人困惑的形态和分子特征。其运动形式为亚圆柱形和单足，具有单轴细胞质流，偶尔在前缘出现透明肿胀（单极形态型）。基于这组特征，这种变形虫与 Nolandella 属（Tubulinea，Euamoebida）的成员最为相似。然而，仅基于小亚基核糖体 RNA（SSU rRNA）基因和两个串联标记（SSU rRNA 基因和肌动蛋白）的分子系统发育分析，将该物种牢固地置于 Discosea 中，特别是与 Dermamoeba 和 Paradermamoeba（Dermamoebida）亲缘关系最近的一个分支中，以及来自环境 DNA 的几个 SSU rRNA 克隆。研究中的变形虫独特的糖萼由复杂的独立单元组成，具有五聚体对称性，可被视为该物种与其他 Dermamoebida 的统一特征。这些变形虫表现出的单极形态型主要发生在 Tubulinea 中，但最近在变形虫的其他分支（例如 Dactylopodida 和 Variosea）中得到了证实。这种形态型可能是变形虫细胞组织的原始模式，可能在最后一个变形虫共同祖先（LACA）中进化而来，并在该组的几个谱系中保守。它可能反映了变形虫细胞骨架结构和功能的基本特征。
