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"is it not Exoprosopa (Cladodisca) rivularis? Was the species migrated from Exoprosopa to Heteralonia? "

it is the same thing, looking at it a bit harder i see fauna europa uses Exoprosopa rivularis (Meigen). in Evenhuis and Greathead 1999 it is under "subgenerically unplaced species of Heteralonia". i think Fauna Europa superceeds Evenhuis and Greathead so best to follow that nomenclature, at least in this case.