This poorly understood but certainly distinct cassia belongs in the complex of forms related to C. barbata and C. belemii that is characterized by pale flaking epidermis of the annotinous branchlets. Of all Absoideae only C. chapadae resembles it in the strongly recurved margins of the leaflets combined with venation impressed on the upper but sharply elevated on the lower face; this however is obviously different in the dense villous vesture of the stems and the smaller, cuneate-obovate leaflets highly glossy on the upper face. Cassia belemii and C. salvatoris, both endemic to the Atlantic lowlands of Bahia, appear similar to C. rugosula in the stiff, early lignescent branchlets clad in pallid epidermis, but both have plane-margined leaflets veiny on the upper face. lf the type-locality of C. rugosula is correctly recorded, its range must coincide on the Minas-Goias boundary with that of C. acosmifolia var. oropedii which, already different in character of the epidermis, differs further in the lax racemes combined with prominulous, not engraved primary venulation of the thinner, greener leaflets.