Two freshwater tardigrade populations belonging to the genus Dactylobiotus were investigated using phase contrast microscopy, scanning electron microscopy, and molecular markers commonly employed in tardigrade phylogenetic studies (18S rRNA, 28S rRNA, ITS2, and COI). The population from Taiwan, discovered through social media, represents a new species, described here as Dactylobiotus taiwanensis sp. nov. This species is most similar to Dactylobiotus parthenogeneticus but differs in the presence of singular rings of pores surrounding the egg processes and specific morphometric traits. The second population, from Greenland, was provisionally identified as D. cf. octavi, and its morphological discrepancies are discussed in detail. A revision of the type material for Dactylobiotus caldarellai and Dactylobiotus lombardoi raises questions about their validity due to insufficient data. Finally, a phylogenetic analysis incorporating taxa from the family Murrayidae, along with the newly sequenced populations, is presented. An updated dichotomous key for the genus Dactylobiotus is also provided.
Meiofauna, Taxonomy, Freshwater, Egg ornamentation, New species
