Phylogenetic placement of the protosteloid amoeba Microglomus paxillus identifies another case of sporocarpic fruiting in Discosea (Amoebozoa)

Abstract

Protosteloid amoebae are a paraphyletic assemblage of amoeboid protists found exclusively in the eukaryotic assemblage Amoebozoa. These amoebae can facultatively form a dispersal structure known as a fruiting body, or more specifically, a sporocarp, from a single amoeboid cell. Sporocarps consist of one to a few spores atop a noncellular stalk. Protosteloid amoebae are known in two out of three well‐established major assemblages of Amoebozoa. Amoebae with a protosteloid life cycle are known in the major Amoebozoa lineages Discosea and Evosea but not in Tubulinea. To date, only one genus, which is monotypic, lacks sequence data and, therefore, remains phylogenetically homeless. To further clarify the evolutionary milieu of sporocarpic fruiting we used single‐cell transcriptomics to obtain data from individual sporocarps of isolates of the protosteloid amoeba Microglomus paxillus. Our phylogenomic analyses using 229 protein coding markers suggest that M. paxillus is a member of the Discosea lineage of Amoebozoa most closely related to Mycamoeba gemmipara. Due to the hypervariable nature of the SSU rRNA sequence we were unable to further resolve the phylogenetic position of M. paxillus in taxon rich datasets using only this marker. Regardless, our results widen the known distribution of sporocarpy in Discosea and stimulate the debate between a single or multiple origins of sporocarpic fruiting in Amoebozoa.

Living in the cracks: Two novel genera of Variosea (Amoebozoa) discovered on an urban sidewalk

“…Additionally, the topology of the tree, including the deep branches, matches previous phylogenomic analyses of Amoebozoa (Kang et al., 2017) to the exclusion of the Tevosa clade from Kang et al., 2017 previously demonstrated in Tice et al. (2023) and Tekle et al. (2022).…”

“…As in the SSU rRNA gene phylogenies, the phylogenomic analyses illustrate that our new isolates are paraphyletic of one another, with Union 16-1-3 and MSU2-1 grouping together. Additionally, the topology of the tree, including the deep branches, matches previous phylogenomic analyses of Amoebozoa (Kang et al, 2017) to the exclusion of the Tevosa clade from Kang et al, 2017 previously demonstrated in Tice et al (2023) and Tekle et al (2022). Rather in our analyses and these latter studies Evosea groups with Discosea.…”

Comparative analysis of mitochondrion-related organelles in anaerobic amoebozoans

“…In one [33], Rhizomastixidae forms a sister lineage to Pelomyxidae, but maximum-likelihood analysis of the same dataset preferred the alternative, in which Pelomyxidae and Mastigamoebidae are sisters. The latter was recovered in other studies [64, 65] and in our SSU rDNA phylogeny (Fig. S1), and will serve as the framework for our evolutionary inferences.…”

“…The sampling captures different lifestyles and comprises representatives of all major Archamoebae lineages (Figs 1a and S1, available in the online version of this article). The placement of the Rhizomastixidae clade is conflicting in phylogenomic analyses [33,64,65]. In one [33], Rhizomastixidae forms a sister lineage to Pelomyxidae, but maximum-likelihood analysis of the same dataset preferred the alternative, in which Pelomyxidae and Mastigamoebidae are sisters.…”