Due to the high variability of Pseudofusus rostratus, it is not surprising that Monterosato has included rusticulus in the latter. « Another important form, particular of these regions, is no more than 15 millimetres long, carinate, with strong nodules so protruding that they seem thorny, with a uniform tawny colour. It will be possible to distinguish it with the name of rusticula. » – T. A. di Monterosato: “Notizie intorno ad alcune conchiglie delle coste d’Africa”, Bullettino della Società Malacologica Italiana vol. V, Pisa 1879, p.227.