Coronamoeba villafranca gen. nov. sp. nov. (Amoebozoa, Dermamoebida) – the first marine amoeba related to Dermamoeba and Paradermamoeba, challenges the correlation of morphology and phylogeny in Amoebozoa

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 anterior edge (a monotactic morphotype). Based on this set of characters this amoeba is most similar to the members of the genus Nolandella (Tubulinea, Euamoebida). However, molecular phylogenetic analysis based on the single marker 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 relatives. A unique glycocalyx of the studied amoeba consisting of complex separate units with pentagonal symmetry may be considered a unifying character of this species with other dermamoebids. The results obtained favor a hypothesis that the monotactic morphotype that primarily occurs in Tubulinea, but was recently confirmed in other clades of Amoebozoa (e.g. Dactylopodida and Variosea) may be the plesiomorphic mode of amoeboid cell organization in this supergroup. It may reflect basic characters of the cytoskeletal structure and functions in Amoebozoa.