Micrognathozoa, or ‘little jaw animals’, are one of the ~32 evolutionarily independent lineages on the animal tree of life. This phylum contains some of the smallest animals reaching a maximum size of 150µm. Populations are found in Greenland, the Pyrenees Mountains, and a Subantarctic island. Despite this disjoint distribution, there is currently only one described species, Limnognathia maerski. After almost a decade of collecting effort, the Katrine Worsaae group here at BIO, UCPH, joining teams from USA, UK, France, and Spain, was able to collect samples from all three populations. With this new material, using advanced microscopy, single-cell transcriptomic techniques, and machine learning, we interrogate the relationships among populations, test species limits, and infer their biogeographic history for the first time. Although we find no morphological differences, genetic data distinguish the Subantarctic population as a separate species, here named Limnognathia desmeti. The distribution of this old freshwater phylum, Micrognathozoa, can only be explained by overseas dispersal which raises questions about potential dormant life stages and undiscovered populations.
Our paper describing the second species of Micrognathozoa, Limnognathia desmeti, is out: doi.org/10.1098/rspb... - big thanks to all coauthors, to Willem H. De Smet for finding this species, and to the Villum Foundation a.o. for supporting this project!
