Its epithet cassa is derived from the Latin cassus, meaning "devoid", due to this species' lack of medullar reactive substances.

The species' axillary sinus is oval, it counts with rounded apices, and a black-lined margin with no cilia.

Its medulla is white, while its underside possesses a rugose, veined and papillate margin.

Its rhizines are dimorphic, measuring between 0.1 to 0.4 millimetres (0.0039 to 0.0157 in) long, being coloured black and with a frequent distribution.

[1] This species was first found in the Parque Natural do Caraça, in Minas Gerais, at an altitude of 1,330 metres (4,360 ft) on a tree in a light forest.