Single specimens of Alona weltneri is only recorded from two different delta localities situated in the central parts of South Norway.
Alona weltneri has a carapace with longitudinal lines, which is rounded at the posterior ventral corner. The oscellus is situated nearer to the eyes than to the apex of the rostrum. The postabdomen is tapering slightly towards the end which forms a right angle with the base of claws. The denticles fastened to the dorsal edge of postabdomen are relatively small and widely separated.
Female: Length 0.4–0.5 mm
Ecology and distribution
A. weltneri is a littoral species which is only recorded from two different delta localities situated in the central parts of South Norway, respectively the delta of The River Etna-Dokka (134 m a.s.l.) and The River Lågen (123 m a.s.l.). Only one specimen has been found in each of the two deltas. The two records are from vegetated areas, protected from the main stream. pH was about neutral (7.0) in both deltas, while conductivity was respectively 6.8 mS/m (The River Dokka) and 7.1 mS/m (The River Lågen).