This species is characterized by its elliptic leaves with rather short stout petioles, its short thickened elliptic to ligulate stipules that are covered with a dense group of glands, its pedunculate cymose inflorescences with rather small shortly pedicellate flowers, and its medium-sized white ellipsoid fruits. The stipules are distinctive in form but quickly deciduous and also the flowers are apparently borne with a flush of new leaves that later become quite a bit larger, so that fruiting specimens of this species are difficult to identify. The name Rudgea hispidula was considered by Zappi (2006) to be a synonym of Rudgea cornifolia, but the type specimen has the distinctive enlarged, densely glandular, caducous stipules of Rudgea spinigemmia Zappi, which she considered a separate species from Rudgea cornifolia and which is here considered a synonym of Rudgea hispidula. The only difference evident between the types of these two names, both of which are in bud, is the glabrous inflorescence of Rudgea spinigemmia vs. the pilosulous or hispidulous inflorescence of Rudgea hispidula; additional collections now document the distribution of this species as apparently continuous between the type localities of these two names, and the hispidulous inflorescences as rare and perhaps localized in northeastern Peru, or perhaps the pubescence of those is deciduous.

Rudgea hispidula is similar to Rudgea crassipetiolata and Rudgea clerodendroides, and these were distinguished when they were described basically by their calyx limbs: deeply divided into very narrow acuminate lobes in Rudgea crassipetiolata, and 4-5 mm long and irregularly lobed in Rudgea clerodendroides. Some plants from central Peru are robust and appear in general aspect to represent Rudgea crassipetiolata and their specimens have been identified as this species, but these plants have calyx limbs 1-1.5 mm long that are undulate to shortly divided with broadly triangular lobes, and these plants are here included in Rudgea hispidula.

Rudgea hispidula and Rudgea crassipetiolata have been confused with Ixora rudgeoides, which is sympatric.