Phytomonas

Phytomonas is a genus of trypanosomatids that infect plant species. Initially described using existing genera in the family Trypanosomatidae, such as Trypanosoma or Leishmania, the nomenclature of Phytomonas was proposed in 1909 in light of their distinct hosts and morphology. When the term was originally coined, no strict criterion was followed, and the term was adopted by the scientific community to describe flagellate protozoa in plants as a matter of convenience. Members of the taxon are globally distributed and have been discovered in members of over 24 plant families. Of these 24, the two main families that are infected by Phytomonas are Euphorbiaceae and Asclepiadiacae. These protists have been found in hosts between 50° latitude North and South, and thus they can be found on all continents save for Antarctica.

Phytomonas is believed to have arisen from a single monoxenous lineage of insect parasitizing trypanosomatids some 400 million years ago. After this divergence, a heteroxenous lifestyle was developed, and most Phytomonas species are transferred between plant hosts by insect vectors in the Heteroptera suborder as a form of dixenous parasitism. Species with considerable economic impact include Phytomonas leptovasorum and Phytomonas staheli, the causative agents of phloem necrosis in coffee and wilt of coconut and oil palms, respectively.