3) Macropsychanthus wiakabumba Fonseca-Cortés, R.Clark & L.P.Queiroz, sp. nov. Type: Papua New Guinea, District Morobe, Subdistrict Lae, about 2 km south of Timini village, along Lae-Bulolo road, 6°50’S 146°50’E, 9 May 1977, J. Wiakabu & T. Umba 70394 (holotype: NSW-863173!; isotypes: A-2261614!, BISH, BM, BO, BRI-AQ355171!, CANB-00549252!, E!, K-0009800354!, L-1953109!, M, PNH, QRS, SING, US-02343836!). Fig. 6. Combinatione foliolis rugosis 8–11 paribus venarum donatis, floribus 1.4–1.7 cm longis vexillo 10–14 × 6–8 mm, alis 12–14 × 4–6 mm et carina 12–15 × 3–6 mm, atque decem staminibus fertilibus, inter species generis unica. Lianas. Stems terete, brown, hollow when young; hirsute and fulvous on the stems, young branches, stipules, stipels, petiole, petiolules, rachis and inflorescence. Stipules 10–20 × 2–4 mm, medifixed, upper and lower lobes of similar length. Petiole 7–13 cm long, sulcate; rachis 20–30 mm long, sulcate; stipels 5–7 mm long, linear; petiolules 7–10 mm, terete; leaflets chartaceous, elliptic to ovate, base rounded, truncate, cordate or slightly attenuate, apex 5–10 mm long, mucronate or rounded; secondary veins 9–11 pairs, dorsal and lower surface strigose fulvous; lateral leaflets 10–14 × 8–10 cm; distal leaflet 12–15 × 8–10 cm. Pseudoraceme 55–85 cm, erect, axillary or terminal; peduncle of inflorescence 30–45 cm long; brachyblasts 3–7 mm, incurved, stalked, 5–15 mm apart; first-order bract (at the brachyblast attachment) 7–12 × 2–3 mm, lanceolate, erect or reflexed; second-order bract (at the pedicel attachment) 1–2 × 1–2 mm, ovate, sericeous, fulvous; bracteoles 1–2 × 1–2 mm, rounded, sericeous, fulvous; pedicel 4–6 mm long. Flowers 1.4–1.7 cm long; calyx 5–7 × 5–7 mm, campanulate, without a hump behind the dorsal sepal, strigose, fulvous on the outside and velutinous fulvous on the inside; dorsal lobe 3–4 × 4–6 mm, rounded, emarginate; lateral lobes 3–5 × 3–5 mm, triangular, falcate; lower lobe 3–4 × 2–4 mm, lanceolate; petals glabrous, purple; standard petal 10–14 × 6–8 mm, elliptic, with two callosities at the base, with two basal auricles, apex emarginate, claw 3–4 × 1–2 mm; wing petals 12–14 × 4–6 mm, lower lobe rounded, apex rounded, claw 4–5 × to 1 mm, with a dorsal spur at the base of the claw; keel petals 12–15 × 3–6 mm, apex with one rounded beak, claw 4–6 × to 1 mm, with a dorsal spur at the beginning of the claw; stamens up to 15 mm long; all fertile, ovary 5–8 mm long, 3-ovulate, covered with canescent sericeous indumentum, style up to 5 mm long, linear, stigma capitate. Legume and s eeds unknown. Etymology. The specific epithet honors J. Wiakabu and T. Umba for their contributions to advancing knowledge of the flora of Papua New Guinea. Distribution and habitat. Macropsychanthus wiakabumba is known only from a single locality in Papua New Guinea (Fig. 3F). Preliminary conservation assessment. This species is only known from the type, collected in 1935 from eastern Papua New Guinea. Based on this single collection, the Extent of Occurrence (EOO) and Area of Occupancy (AOO) are both estimated as 4 km 2, below the thresholds for Critically Endangered under criteria B1 and B2. The single known collection was made in disturbed lowland forest, and much of the area surrounding the type locality within the elevation range of this species is a mosaic of land cleared for shifting agriculture and secondary forest. However, this species may be able to persist in secondary forest as observed for other species in the genus. While its apparently highly restricted distribution makes this species vulnerable to stochastic effects, it is difficult to determine if it is experiencing a continuing decline given the lack of data on its population status. If found to be experiencing a continuing decline, this species could qualify as Critically Endangered under criterion B. If, however, it is not found to be threatened at its single known locality, this species would qualify for Least Concern. It is also possible that this species is much more widespread than is currently known, and it may occur at other localities in Papua and New Guinea, or even on nearby islands. As the uncertainty spans the full range of categories, we propose its classification as Data Deficient (DD) following the IUCN (2024) criteria. Comments. Macropsychanthus wiakabumba exhibits a distinctive morphology not observed in any other species of Macropsychanthus, particularly in its rugose leaflets with 8–11 pairs of secondary veins, very small flowers (1.4–1.7 cm long), standard petal 10–14 × 6–8 mm, wing petals 12–14 × 4–6 mm, keel petals 12–15 × 3–6 mm and ten fertile stamens. In vegetative morphology, it resembles M. ferrugineus and M. hexander due to the presence of a hirsute indumentum and a similar number of secondary veins in the leaflets. However, M. hexander is distinguished by its larger flowers (2–2.5 cm long), standard petal 17–20 × 13–17 mm, wing petals 17–20 × 7–12 mm, keel petals 14–18 × 7–12 mm, and six fertile stamens and four staminodes. In contrast, M. ferrugineus has flowers measuring 2.5–3 cm long, standard petal 25–30 × 18–22 mm wing petals 25–30 × 10–12 mm, keel petals 25–30 × 10–12 mm, and ten fertile stamens.

Published as part of Fonseca-Cortés, Andrés, Clark, Ruth P., Snak, Cristiane & Queiroz, Luciano Paganucci De, 2025, A Taxonomic Revision of Macropsychanthus (Leguminosae-Papilionoideae) Reveals New Species and New Circumscriptions in Southeast Asia and Oceania, pp. 93-120 in Phytotaxa 720 (2) on pages 100-103, DOI: 10.11646/phytotaxa.720.2.1, http://zenodo.org/record/18415323