One or more longitudinal rows of smaller to larger setae in the median part of the scutum, the rows being either regular or irregular (with setae more or less scattered).
Does someone has a scan of Nartshuk E.P. 2003. Key to families of Diptera (Insecta) of the fauna of Russian and adjacent countries. Proceedings of the Zoological Institute Vol. 294: 1-252 for me?