Diacyclops cohabitatus Monchenko 1980 known only from the groundwater of the Carpathian mountains in Ukraine is redescribed
from specimens collected in the Danube alluvial plain, the Lobau, at Vienna. In this area two stygobiont species belonging
to the D. languidoides - group co-occur as well. D. cohabitatus can be differentiated from these latter Diacyclops species
on the basis of several morphological traits of antennae, P4 and caudal rami. Its relationship with other members of the D. languidoides
- group (e.g. D. languidoides goticus) is discussed.