[1][3] Armadilliidum ruffoi belongs to the "Marginiferae" section of the genus, which is characterized by side edges of the forehead that bend upwards into distinct lobes.

Additionally, the species is thought to be closely related to the probably sympatric A. germanicum or even conspecific with it, consisting its southernmost variety.

The frontal shield surpasses the anterior edge of the head, has a slightly convex upper margin, and lateral angles that are almost right.

The head itself has a distinct longitudinal groove in the middle, immediately behind the frontal shield, that is delimited in each side by two low ridges.

[1] Concerning the sexual characters of the male, the seventh pereiopod has a ventrally straight ischium, decorated with a hair field at its apical part.