Phylogenomics of free-living neobodonids reveals they are a paraphyletic group from which all other metakinetoplastids are descended

Kinetoplastea is a major taxon of microbial eukaryotes that includes the well-known trypanosomatid parasites, species of which cause sleeping sickness, Chagas' disease and leishmaniases in humans, as well as various animal and plant diseases. Free-living kinetoplastids are greatly understudied compared to their parasitic relatives, but are ecologically important microbivores, and collectively comprise the great majority of kinetoplastid diversity. For two decades kinetoplastids have been divided into prokinetoplastids and metakinetoplastids, with the latter further split into four orders, the most diverse of which is Neobodonida. However, the position of the root of the metakinetoplastids and whether neobodonids are a clade has remained unclear due to a lack of multi-gene data from free-living kinetoplastids, particularly neobodonids. Here, we present transcriptomic data for seven newly or recently cultivated free-living neobodonid kinetoplastids. Phylogenomic analyses of a de novo generated data set of 469 inferred orthologs and 45 taxa robustly resolve the kinetoplastid tree, including the position of the root of metakinetoplastids. This divides metakinetoplastids such that Trypanosomatida, Eubodonida, Parabodonida, Allobodonidae (formerly neobodonid clade "1E") and neobodonid clade "1D" fall on one side, while neobodonid clades "1B" (Rhynchomonadidae) and "1C" fall on the other. Neobodonids are thus inferred to be a paraphyletic group from which all other metakinetoplastids descend. This analysis is the most thorough examination of metakinetoplastid phylogeny thus far, and forms a new basis for tracing the evolutionary history of the entire kinetoplastid group.