Piercing the veil: A novel amoebozoan (Janelia veilia n. gen. n. sp.) reveals deep clades within Discosea through phylogenomics

Abstract

Three major groups of primarily amoeboid taxa are present across Amoebozoa: Discosea, Evosea, and Tubulinea. While each of these groups were thought to have morphologically unique traits and members, the morphologic boundaries between each group have recently blurred. For example, it is demonstrated that several taxa in each group display monopodial limax amoebae, a characteristic most often associated with Tubulinea. Here we describe a novel discosean amoeba isolated from a freshwater pond, Janelia veilia n. gen. n. sp. Its cells have variable morphologies, but often display monopodial limax amoebae, with a unique trailing structure that appears to be derived from cellular material. In some cases, cells have conical pseudopodia or pointed pseudopodia. Using phylogenomics, we find that this taxon branches as sister to the recently described discosean Mycamoeba gemmipara and the sporocarpic protosteloid amoeba Microglomus paxillus, forming an order-level group we term Mycamoebida. Mycamoebida is fully supported as sister to Dermamoebida, together forming a subclass we term Dermelia. SSU rRNA phylogenies show that Janelia veilia n. gen. n. sp. is molecularly unique from any known organism, but branches with high support in a clade containing Mycamoeba gemmipara and several environmental sequences suggesting a larger diverse clade within Discosea.