Calanthe aruank P.Royen, Alp. Fl. New Guinea 2 (1979) 143, fig. 59
Type: Schodde 1891 a (holo CANB)
Terrestrial, 32-55 cm high. Rhizome short, erect. Stem none. Roots stout, fleshy, scattered pilose. Leaves almost rosulate, blade patent, herbaceous, glabrous, broadly elliptic, 6.5-10 by 1.83.2 cm, acuminate, base petiole-like, 5-8-nerved with some less strongly developed nerves in between, nerves slightly prominent above, prominent below, margin wavy. Inflorescence 12-18-flowered, 30-53 cm long. Peduncle rather densely spreading-retrorse pilose, angular, 23-30 cm long, along its entire length with 6-8 tubular-infundibuliform, 0.5-1.5 cm long scales, the higher ones with gradually smaller tubular parts, all obliquely truncate and acute at tip, apical ones leaf-like. Rachis with the same pubescence as peduncle, slightly flexuose, 7-23 cm long. Floral bracts obovate-elliptic, 0.5-1.2 by 0.2-0.5 cm, acute, nerved. Pedicels scattered white pilose, very slender, 0.4-0.6 cm long. Ovary scattered pilose, falcate-clavate, 0.3-0.4 cm long, 6-grooved. Sepals and petals spreading backwards. Median sepal glabrous, broadly oblong-elliptic, 0.6-0.85 by 0.254 cm, retuse, 3- or 4-nerved. Petals [?lateral sepals?] glabrous, slightly obliquely oblong-elliptic, 0.65-0.76 by 0.2-0.25 cm, truncate-retuse, 1-nerved. Lip glabrous, 3-lobed, lateral lobes obliquely oblong-elliptic, 0.3-0.4 by 0.2-0.25 cm, obtuse, median lobe 2-lobed, 0.25-0.3 by 0.35-0.4 cm, each lobe oblong, 0.24-0.28 by 0.15 cm, obtuse, base on inside with 3 longitudinal crests, central one extending along entire free part of lip, the 2 lateral ones about halfway the median callus to the column, all calli irregularly bullate, glabrous; spur cylindrical, 0.9-1 cm long, clavate swollen at tip. Column short and broad, 0.45-0.55 by 0.3-0.35 by 0.3-0.35 cm, deeply retuse at tip. Anther cucullate, 0.15 by 0.1 by 0.1 cm, truncate at tip, retuse at base. Pollinia 8, pyriform, 0.06 cm long. Capsule not seen. (After Van Royen, 1979).