[Copepodid stage of Dichelesthium oblongum (Abildgaard, 1974), a parasitic copepod of the sturgeons].

The morphology of a copepodid found on Huso huso near the delta of the Volga is described and illustrated. The copepodid bears general resemblance to those of Caligidae but differs from them in absence of the frontal filament and in possession of a primitive first maxilla. It is concluded that the copepodid belongs to Dichelesthium oblongum and that Dichelesthiidae might be more closely related to Caligidae than has hitherto been suspected.