Type: — BRAZIL. Amazonas: boca do rio Içana, local chamado Boa Vista (antigo Grilo), 12 Nov 1987, Kawasaki 112 (Holotype, WAG!, isotypes, MO!, NY!).

Laxoplumeria longipetiolata is easily recognized by its leaves with petioles 50–62 mm long, corolla tube 2.9–3.1 mm and nectaries slightly shorter than the ovary.

Trees ca. 10 m, stems glabrous, sap unknown. Leaves alternate, petioles 50–62 mm; leaf blade 17–21 × 7.5–9 cm, obovate, apex obtuse to rounded, base acute, glabrous, with 15–17 pairs of secondary veins. Inflorescences 14–16 cm long, glabrous, peduncles 85–105 mm, pedicels 2.8–3.2 mm, bracts 0.2–0.7 mm; calyx lobes 1.3–1.5 mm, ovate, the apex obtuse, glabrous; corolla white, glabrous, tube 2.9–3.1 × 1.1–1.3 mm, lobes 6–7.5 × 0.8–1.5(–2) mm, narrowly elliptic to narrowly ovate-elliptic; stamens inserted in the distal part of the corolla tube, near the mouth, anthers 1–1.2 mm; ovary ca. 1 mm, nectaries slightly shorter than the ovary. Follicles unknown.

Distribution and habitat: — Endemic to the Amazonas state, Brazil, growing in caatingas below 100 m. Flowering in November.

Observations:— Laxoplumeria longipetiolata is easily recognized by its leaves with petioles 50–62 mm long.