Echthrus reluctator is a variable species, both in size and colour. It is not impossible that a revision will show that there are more than one species. In Taxapad I find a few Echthrus (longicornis, breviformis, cryptiformis) with uncertain status from Germany, Poland and Hungary.
From what I have seen in literature Echtrus reluctator is known from VE, Tjøme, Vasser, HOY, Bergen, HOI, Kvinnherad and Ullensvang (first found in 1941). No records in Artskart.