In the interests of taxonomic stability I here suggest that Asilus incisuralis Macquart, 1838 should be considered a synonym of Synolcus acrobaptus (Wiedemann, 1828) until proved otherwise.
Wiedemann (1828)--Described Asilus acrobaptus from 'Bom Kap' (i.e.
Macquart (1838)--Described Asilus incisuralis with the brief comment 'L'un et l'autre sont du Cap.
Macquart (1846)--Described Asilus dubius from 'Port Natal, et de la Cafrerie'.
Oldroyd (1980) included Asilus incisuralis Macquart, 1838 in the Afrotropical Catalogue without explanation, and so it remains necessary to check the type(s) of this species in order to verify the assignment.
Type species: Asilus glaucius Rossi, 1790, by subsequent designation (Engel 1930: 363).
Two are definitely represented by type specimens in the BMNH (Asilus firmatus--now a Dysclytus, and Trupanea venerabilis--now a Promachus/Bactria).