Plants 14–28 cm tall. Leaves 2–3, basal, rosulate, petiolate; petiole up to 3.5 cm long; blade up to five cm long and 2.3 cm wide, ovate, oblong-lanceolate to oblong-ovate, acute, glabrous. Peduncle delicate, erect, glabrous, glandular, with three cauline sheaths, terminated by a loosely few-flowered raceme usually up to three cm long. Flowers small, white, sepals sparsely glandular. Floral bracts six mm long, lanceolate, glabrous. Pedicellate ovary up to 11 mm long, densely glandular. Dorsal sepal six mm long, three mm wide, ovate- deltoid, widest near the middle, subobtuse, with 5, sparsely anastomozing veins. Petals unguiculate; claw free part 1–1.2 mm long, narrow; lamina 4.6 mm long, 2.3 mm wide, obliquely oblong-ovate, obtuse at both ends, with three branching veins, margins glabrous. Lateral sepals six mm long, 3.8 mm wide, obliquely ovate, subobtuse, somewhat falcate, free to the base, 5-veined. Lip unguiculate, claw free part 1.5 mm long, broadly ovate above narrow base, margins upcurved, foming a kind of channel; lamina 2.5 mm long, five mm wide, transversely elliptic in general outline, auriculate or cordate at the base, subcordate at the apex, concave, glabrous, 3-lobed apically; lateral lobes obliquely elliptic-ovate; middle lobe 0.5 mm long, ca 0.3 mm wide, linear, obtuse, appearing at the bottom of shallow sinus. Gynostemium 2.6 mm long in total, shortly stalked (Fig. 10).
Ecology: Terrestrial in the fields and forests. Flowering in October

This species has been originally compared with Ecuadorian-Peruvian congener— P. parvilabris (Lindl.) Rchb.f. (Szlachetko & Kolanowska, 2013). Both species differ in floral segments. Although, similar in general outline, the lip makes them easily separable. The lip of P. castanedae is prominently auriculated basally, and devoided of any calli, the claw margins are upcurved forming a kind of channel directed to the base of the lip. In P. parvilabris lip claw is semiterete, lamina possesses cuneate base, and a pair of keel-like, fleshy calli at base. Additionally, petal’s claw of this species is shorter than lower lobe, whereas in P. parvilabris petal’s claw is as long as or longer than lower lobe. Lateral sepals of P. castanedae are obliquely ovate versus obliquely elliptic-ovate in P. parvilabris. Ponthieva castanedae can be distinguished from other representatives of P. rostrata group by having relatively wide claw with upcurved margins. Claw lateral lobes are oblong elliptic and the base of lamina is cordate.