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bioRxiv · 10.1101/2024.03.12.584707

Characterisation of Skoliomonas gen. nov., a haloalkaliphilic anaerobe related to barthelonids (Metamonada).

Eglit, Y.·Williams, S. K.·Roger, A. J.·Simpson, A. G. B.
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Abstract

Metamonads are a large and exclusively anaerobic clade of protists. Additionally, metamonads are one of the three clades with a proposed excavate ancestral cell morphology, characterised by a conspicuous ventral groove often accompanied by a posterior flagellum with a vane. Here, we characterise four isolates of an anaerobic bacterivorous flagellate from hypersaline and alkaline soda lake environments, which represents a novel clade. Small subunit ribosomal RNA (SSU rRNA) gene phylogenies support recent phylogenomic analyses in placing this clade as the sister group to Barthelona spp., a lineage that is itself sister to or deeply branching within Fornicata (Metamonada). The cells have a distinctive morphology comprised of a hunchbacked cell body with a narrow twisting ventral groove ending in a large opening to a conspicuous cytopharynx curving up the dorsal side of the cell. The right margin of the groove is defined by a thin lip that twists slightly to the left towards the posterior. The posterior of the cell ends in a spike up to half a cell body long. The posterior flagellum bears a wide ventral-facing vane. One isolate forms cysts with a complex wall and a single plug. The narrow ventral groove and elongate cytopharynx are shared with barthelonids. We describe one isolate as Skoliomonas litria, gen. et sp. nov. Further investigation of mitochondrial-related organelles (MRO) in Skoliomonas spp. and detailed ultrastructural studies would be important to understanding the evolution of adaptation to anaerobic conditions in Metamonads--especially fornicates--as well as the evolution of the excavate groove.

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Eglit, Y., Williams, S. K., Roger, A. J., Simpson, A. G. B.. 2024-03-14. Characterisation of Skoliomonas gen. nov., a haloalkaliphilic anaerobe related to barthelonids (Metamonada).. https://doi.org/10.1101/2024.03.12.584707

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