Pirum gemmata

Pirum gemmata

Pirum gemmata is a unicellular eukaryote that was isolated from the gut contents of a marine invertebrate, specifically the detritivorous peanut worm Phascolosoma agassizii (Marshall &Berbee 2011). P. gemmata is a member of the Ichthyosporea clade, within the Teretosporea, which is the earliest branching holozoan lineage (Glocking et al. 2013) (Torruella et al. 2015).

P. gemmata’s cultures grow with the development of a mature syncytial stage that undergoes sporogenesis and eventually releases endospores through one or more openings in the parent cell wall. Mature cells are multinucleated, with a cell wall, and can measure up to 200 μm (Marshall &Berbee 2011). Endospores are amoeboid and some have pseudopod-like cell extensions.

P. gemmata can easily be cultured axenically in marine broth medium. Given its phylogenetic position as a close unicellular relative of animals, P. gemmata could potentially provide important insights into the origin of multicellular animals.


-Glockling SL, Marshall WL, Gleason FH. (2013). Phylogenetic interpretations and ecological potentials of the Mesomycetozoea (Ichthyosporea). Fungal Ecology, vol.6, 4, 2013,pp 237-247.

-Marshall, Wyth L., David J.; Berbee, Mary L. (2011) “Facing Unknowns: Living Cultures (Pirum gemmata gen. nov., sp. nov., and Abeoforma whisleri, gen. nov., sp. nov.) from Invertebrate Digestive Tracts Represent an Undescribed Clade within the Unicellular Opisthokont Lineage Ichthyosporea (Mesomycetozoea)”.  Protist, Vol. 162.

-Torruella, G., de Mendoza, A., Grau-Bové, X., Antó, M., Chaplin, M. A., del Campo, J., Eme, L., Pérez-Cordón, G., Whipps, C., Nichols, K. M., Paley, R., Roger, A. J., Sitjà-Bobadilla, A., Donachie, S., and Ruiz-Trillo, I. (2015). Phylogenomics reveals convergent evolution of lifestyles in close relatives of animals and fungi. Current Biology 25(18):2404-10.