. Paulliniawurdackii differs from P.ingifolia Juss. by the lanate or lanate-tomentose stems and inflorescence axes (vs. tomentose or tomentulose), the oblong-lanceolate, ovate or deltate bracts 9–15 mm long that enclose the cincinni (vs. deltate, 1–2.5 mm long, not enclosing the cincinni), the ovate-lanceolate bracteoles 4–5 mm long (vs. deltate, ca. 1 mm long) and the sessile, depressed-globose capsules (vs. long stipitate, globose or trigonous-globose).

ECUADOR. Orellana; Yasuní Forest Reserve, 1 km W of PUCE Scientific Station, moist forest along road, 0°41.956'S, 76°28.075'W, 250–300 m elev., 5 Jul 1995 (fl♀), Acevedo-Rodríguez & J.A. Cedeño 7654 (holotype US!, isotype QCA).

Liana 20–25 m long. Stem terete, ferruginous lanate or lanate-tomentose, becoming glabrous and lenticellate with age, producing abundant milky sap; cross section simple, up to 10 cm diam. Stipules early deciduous, leaving a scar 7–10 mm wide. Leaves imparipinnate with 1 basal pair of trifoliolate pinnae and 2 or 3 pairs of simple lateral leaflets (thus with 11 or 13 ultimate leaflets); petiole and rachis winged; petiole 10.5–23.5 cm long, wings 0.4–0.8 cm wide; rachis 7–14 cm long, wings 0.4–0.7 cm wide, puberulent; lower pair of trifoliolate pinnae with winged petiolules 1.4–1.8 cm long; leaflets 13.5–16 × 3.8–4.5 cm, coriaceous, oblong, oblong-elliptic or less often oblanceolate, discolorous, abaxially papillate; cuneate at base on distal leaflet, acute, obtuse, attenuate or sometimes asymmetrical on lateral leaflets, obtusely acuminate to caudate at apex with margins remotely serrate on distal third to half of the blade, teeth with a sub-marginal gland-like callosity; venation craspedodromous, abaxially prominent with scattered setose trichomes, without domatia, tertiary venation reticulate-percurrent between secondary veins. Thyrses terminal, paniculate, 24.5–27 cm long; axes robust, ferruginous lanate or lanate-tomentose; branches 8–16 cm long, with axillary bulbous buds; cataphylls oblong, concave, 13–37 × 8–17 mm, ferruginous sericeous-lanate, deciduous, leaving a scar 5–12 mm wide; bracts 9–15 mm long, oblong-lanceolate, ovate or deltate, flavo sericeous, enclosing the cincinni, which are clothed by overlapping bracteoles, similar in shape, texture and indument to the bracts, but smaller (4–5 mm long), both bracts and bracteoles early deciduous; cincinni 5- to 7-flowered, sessile or sub-sessile; pedicels 2–3 mm long, articulate at middle. Calyx light green when fresh, albo-tomentose when dry, sepals 4, concave, coriaceous, outer sepals ovate, 4–5.5 mm long, inner sepals oblong-ovate, 4.5–7 mm long, the anterior sepal emarginate; petals white to cream, oblong, 4.5–7 mm long, papillate, appendages hood-shaped, 4–5 mm long, crest of posterior appendages emarginate; nectary 4-lobed, the posterior lobes ca. 1.5 mm long, oblong, emarginate at apex, anterior lobes oblong, smaller than the posterior; filaments lanate, 4.5–7 mm long, connate at the very base; gynoecium 3–3.5 mm long; ovary trilobed-ovoid, flavo sericeous-tomentose. Capsule depressed-globose, unwinged, 2–2.3 × 1.8–2 cm, 3-costate, woody, ferruginous sericeous-tomentose, sessile, apiculate at apex; mesocarp 2.5–3 mm thick; endocarp sericeous-tomentose. Seeds oblong-obovate, trigonous in transverse section, entirely sarcotestal, ca. 1.5 cm long.

Western Amazonia, in moist forests between 250–375 m elevation.

Flowering from October to April and known to fruit in July.

The specific epithet honours the late Dr. John J. Wurdack from the Smithsonian Institution, Curator of Melastomataceae and assiduous collector of South American plants, who made one of the first collections of this species.

Known from an EOO of ca. 150,000 km² in western Amazonia on Ecuadorian and Peruvian territories. The new species is known only from 5 collections from this vast area, which seems to indicate that the new species is extremely rare. However, because the species occurs in a National Park in Ecuador and in vastly forested areas of Peru with no immediate threats to the ecosystem, the new species is here treated as least concern (LC) within IUCN guidelines.

ECUADOR. Orellana. Aguarico, Reserva Etnica Huaorani, maxus road and pipeline construction Project, km 100–102, moist primary forest on red soils & undulating hills, 0°56'S, 76°13'W, 250 m elev., 18 Jul 1994 (fr), Pitman 602 (MO, QCNE, US); Sucumbíos, 9.3 km E of Lumbaqui, ca. 0°06'N, 77°16'W, 375 m elev., 29 Apr 1984 (fl), Croat 58698 (MO, NY, QCA, US). PERU. Amazonas. Pongo de Manseriche, on high land, without date (fl), Tessmann 3889 (NY); Provincia Bagua, forested ridge on right bank of Río Santiago, 3–4 km above mouth, 300–350 m elev., 29 Oct 1962 (fl ♂, ♀, fr), J.J. Wurdack 2476 (US).

Paulliniawurdackii is vegetatively similar to P.ingifolia. as both species are robust lianas with imparipinnate leaves with trifoliolate lower pinnae and winged rachides and petioles; oblong, elliptic or oblanceolate leaflets with caudate apices; large deciduous stipules; and unwinged, woody fruits. Paulliniawurdackii however, is easily recognised by its lanate or lanate-tomentose stems and inflorescence axes, the large bracts and overlapping bracteoles that enclose the cincinni and the sessile fruits. While P.ingifolia has a wide distribution that ranges from Costa Rica south to Bolivia, P.wurdackii is restricted to the NW region of the Amazon basin.