| Skoliomonas | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Clade: | Metamonada |
| Clade: | BaSk |
| Genus: | Skoliomonas Eglit & Simpson, 2024[2] |
| Species: | S. litria |
| Binomial name | |
| Skoliomonas litria Eglit & Simpson, 2024[1] | |
| Type strain | |
| TZLM1-RC | |
Skoliomonas is agenus ofanaerobicprotists closely related tobarthelonids, a small group ofbasaleukaryotes within thephylumMetamonada. It is amonotypic genus containing the sole speciesSkoliomonas litria. Members of this genus are informally namedskoliomonads. They are found inhabiting hypersaline alkaline lakes in Tanzania and North America.
The nameSkoliomonas derives from Greek σκολιός (skolios) 'bent', 'crooked', which refers to the hunched appearance of the cell and the twisted venral groove, andμονάς (monas) 'unit', a common suffix used for unicellular protists.[2] Thespecific epithetlitria comes from Ancient Greek ́τρον (litron), an alternative form ofνίτρον (nitron), meaningsodium carbonate; the term was used byHerodotus to describe embalming salts used for mummification inAncient Egypt, harvested from carbonate-rich soda lakes of theNatron Valley. The authors of the species chose the African-specific version of the Ancient Greek word to reflect the African type locality and the possible relevance of these alkaline lakes to local human culture and history.[1]
Skoliomonads areflagellates,unicellularprotists (a type ofeukaryote) that useflagella for movement. Their cells are rounded at their anterior end and pointy at their posterior, with a flattened ventral side and a dorsal hump. The ventral side contains a major groove, which is characteristic of other basal eukaryotes such asexcavates. The cells are asymmetrical: the left side of the cell contains the majority of thecytoplasm, including thenucleus and various largevacuoles for digestion, often containingbacteria which constitute theirprey. The right side is occupied almost entirely by the right edge of the groove.[3] The type isolate, TZLM3-RCL, has been observed forming complexcysts with two walls and a conspicuous plugged pore, something unique among metamonads.[4]
Each cell has two flagella of different lengths, inserted sub-apically and facing the ventral side of the cell. A conspicuous "lip" structure extends from the flagellar insertion along the right side of the ventral groove to the base of the posterior pointy end. The anterior flagellum is around the same length as the cell, and it is pointed forward. The posterior flagellum is twice as long, and features a conspicuously broad flagellar vane around 1 μm wide along the length of the groove, directed away from the cell body.[3]
The ventral groove curves gently to the right as it extends down the cell, and its posterior end has a large opening that gives way to a largecytopharynx underneath its right edge.[5] The cytopharynx, supported by a robust intracellular structure, extends along the dorsal side toward the cell's anterior apex.[6] This is unique to skoliomonads andbarthelonids, since the cytopharynx of most knownmetamonads (Carpediemonas-like organisms) is short, discrete and points toward the left side of the cells. Skoliomonads are similar to most other metamonads in their big flagellar vane, which barthelonids lack.[4]
Skoliomonads areanaerobe microorganisms that feed onbacteria. In particular,Skoliomonas litria is a haloalkaliphilic anaerobe, as it inhabits a hypersaline and alkalinesoda lake.[1]
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| Cladogram of skoliomonads based on a SSU rRNA phylogeny published in 2024.[7] |
ThegenusSkoliomonas was described byprotistologists Yana Eglit and Alastair G.B. Simpson, from strains of metamonad flagellates isolated from alkaline hypersaline sediments found at varioussoda lakes:Lake Manyara inTanzania,Goodenough Lake inBritish Columbia, Canada, andSoap Lake inWashington state, USA.[8] The isolates werecultivated, observed underlight microscopy andtransmission electron microscopy, andgenetically sequenced in order to discover their phylogenetic position.[9] Following the results, the authors published in 2024 the description of this genus, along with itstype and onlyspeciesSkoliomonas litria.[1]
Inphylogenetic analyses using theSSU rRNA gene, aclade composed ofSkoliomonas isolates, informally named "skoliomonads", is the sister group tobarthelonids,[10] which are in turn closely related toFornicata within thephylumMetamonada.[11][12]
