Peristylus alpinipaludosus (P.Royen) Schuit. & de Vogel, in Ormerod, Checklist of Papuasian Orchids (2017) 367.
- Platanthera alpinipaludosa P.Royen, Alp. Fl. New Guinea 2 (1979) 117, fig. 53
- Type: ANU (Hope) 10837 (holo CANB; iso L)
Basionym: Platanthera alpinipaludosa
Erect, 5-22 cm high. Roots fleshy, villose. Stem at base with 1 or 2 sheaths, these 1.2-3 cm long, obliquely truncate, midrib prominent on outside, glabrous. Limb of leaves spreading-patent, subcoriaceous, glabrous, ovate or lanceolate, 1.8-3.2 by 0.71.2 cm, acute, 1-nerved, nerve grooved above, prominent below, margin thin, scattered scarious-papillate; sheaths 1.5-2 cm long, nerved, glabrous. Bracts glabrous, ovate, boat-shaped, 1.8-3 cm long, caudate-acuminate, nerved, reducing towards flowers to 8 by 2 mm. Peduncle glabrous, 1-4.5 cm long, rachis glabrous, 1.5-4 cm long. Pedicels none. Ovary glabrous, twisted, oblong-clavate, falcate, 10-12 by 1.5-2 mm, 6-grooved. Median sepal glabrous, broadly ovate or suborbicular, 4-4.5 by 3-4.5 mm, retuse, 1-nerved, nerve stoutly prominent on outside, margin papillate along apical part, irregularly scarious along rest of margin. Lateral sepals glabrous, obliquely ovate, 3.5-4 by 2.5-3.5 mm, obtuse, lower margin inrolled and slightly saccate, 1-nerved, nerve stoutly prominent on outside, margin irregularly scarious. Lateral petals glabrous, obliquely triangular-ovate, 3-3.5 by 3-3.5 mm, apiculate, 3-nerved with 2 nerves between the main, stoutly prominent nerve and lower margin. Lip glabrous, ligulate, slightly curved upwards, fleshy, 3-3.5 by 2-2.5 mm, obtuse, with one weakly developed lobe at either side of base, limb broadly ridged above, broadly and shallowly grooved below, at mouth of spur with a slightly 2-lobed, transverse callus, 3-nerved at base, 9-nerved in higher part; spur pendulous, clavate, 8-10 mm long, widened, flattened and 2-lobed at tip. Column rugulose, hardly developed, auricles incurved. Anther erect, the 2 cells rather apart and divergent. Rostellum hood-shaped, truncate. Capsule ellipsoid, 3-sided, 10-15 by 3-5 mm, 6-ribbed. (After van Royen 1979)
Note: Examination of the poor isotype material at L as well as van Royen's illustration shows that this species does not belong in the genus Platanthera in which van Royen described it. It is clearly a species of Peristylus in the affinity of Peristylus ciliolatus and Peristylus pachyneurus.