|Importance||of no interest||Ref.|
|Abundance||occasional (usually not seen)||Ref.||Gerstmeier, R. and T. Romig, 1998|
Known from the uppermost Rhine drainage and western tributaries of Danube drainage (Ref. 59043). Common in the Neckar in 1850 (Ref. 10013), but see discussion of identification on pages 60-62. Border to Switzerland (Ref. 556). Considered critically endangered in 1984 (Ref. 27368) and 1992 (Ref. 33852).