A new species of Bragasellus (Isopoda, Asellidae) from NW Spain, with a key to the known species of the genus.

During a survey on the benthic invertebrates of the upper reaches of river Eo (Galicia, NW Spain), a dense population of epigean asellid isopods were detected in the source of the river. After examination, these specimens resulted to belong to a new species of the genus Bragasellus Henry Magniez, 1968. The new species comes to fill a geographical gap between the two alleged ancestral areas of the genus and is characterized by its appendix masculina (male pleopod II endopod), which bears a short but distinct cylindrical cannula and lacks basal process. Other characteristic traits are uniform black pigmentation in live specimens, pereopod I dactylus shorter than the palm of the propodus, smooth (instead of plumose) texture of the marginal setae on male pleopod I exopod, and pleopod III exopod with a straight internal side. In this job, description of the new taxon is provided, as well as a key to all the known species belonging to the genus.