This species is characterized by its extensively twining habit, its sparse to usually dense, yellowed villosulous pubescence, its ovate to elliptic-ovate shortly petiolate leaves, its short cymose inflorescences, its ovate calyx lobes 2-2.5 mm long, and its rather stout white to perhaps red corollas with the tubes 3.5-5.5 mm long and the lobes 1.5-2 mm long. The leaves are characteristically truncate to rounded at the base, relatively rather broad, rugulose, and revolute along the margins. The calyx lobes are broadest at the middle, with the base narrowed, and usually spreading to reflexed. The specimens characteristically dry with a yellow or yellowish brown color. The pubescence varies from dense to sparse, and seems to be at least sometimes deciduous. The typification of this name seems not to be fully resolved. Standley (1931) and Chung (in herb.) included another specimen, Bang 1268, in the circumscription of Manettia bangii, but that specimen is here included instead in Manettia fiebrigii.

Rusby originally described the corollas of Manettia bangii as crimson or purple with tubes ca. 5.5 mm long, and the type of this sname, Bang 537, has only sparse pubsecence. Standley later described a separate species, Manettia tatei, based on a fruiting specimen with dense pubescence. However no distinctions are now evident between these apart from the corolla color reported by Rusby. Therefore these names are here considered synonyms.

Manettia bangii is similar to Manettia fiebrigii, which has lanceolate more slender leaves that are not rugulose, generally appressed or only sparsely villosulous pubescence, and narrower calyx lobes. Manettia bangii is also similar to Manettia tomentosa, with dense hispid to hirtellous pubescence and slightly longer, more slender corollas.