Amomum sabuanum V.P.Thomas, Nissar & U.Gupta, 2014

Thomas, V. P., Nissar, Muhammed & Gupta, U., 2014, Amomum sabuanum (Zingiberaceae): A new species from Sikkim, India, Phytotaxa 159 (2), pp. 122-126 : 122-125

Amomum sabuanum V.P.Thomas, Nissar & U.Gupta , sp.nov. ( Fig. 1 & 2 )

Similar to Amomum kingii but differs in having cuneate lamina bases, white pink-tinged flowers, 3–4 flowers per bract, short peduncles (0–1 cm long), 3-horned calices, smooth walled capsules with concave apices.

Type:— INDIA. Sikkim: East Sikkim District, Pangthang , ICRI field station, 7 May 2007, V . P . Thomas & V . A . Muhammed Nissar 95506 (holotype CAL!, isotype CALI!) .

Rhizome non-stoloniferous, stout, robust, 4–5 cm thick, length/breadth ratio ca. 3, creamy white inside. Leafy shoots 120–200 cm, robust; clump forming; sheath 3–4 cm wide at base, dark pink to maroon towards base and green tinged with pink towards apex, lined with prominent parallel veins, margin ciliate, pubescent externally, glabrous internally. Leaves 5–7 per shoot; lamina oblanceolate, 40–73 × 9.5–18.5 cm, dark green above, glaucous beneath, base cuneate, margin ciliate, slightly wavy, apex acuminate to 1.5 cm long, glabrous except towards the margins on both surfaces, a line of hairs near margin; midrib pinkish, glabrous; veins appressed above; petiole 3–6 cm long, pink tinged with green, densely pubescent internally, glabrous externally. Ligule entire, apex rounded, 0.4–0.9 cm long, coriaceous, maroon, margin ciliate, pubescent externally, glabrous within. Inflorescence 6.5–10.5 cm long, many flowered, arises from the rhizome just below the aerial shoot; peduncle short up to 1 cm long. Outer bract broadly ovate, 2.0–3.5 × 2–3 cm, sterile, 10–12 per inflorescence, chartaceous, brown, prominently veined, margin ciliate, golden hairy externally, glabrous internally; inner bract, oblong, 3.0–3.2 × 1.3–1.8 cm, each bract subtends 3–4 flowers and 1–2 rudimentary flowers, membranous, white, margin ciliate, apex rounded, densely pubescent externally, glabrous within. Bracteole non-tubular, lanceolate to triangular, 1–4 × 0.5–1.3 cm, white, size varies in a cincinnus, smaller towards centre, often represented by rudimentary structures, margin ciliate, apex acute, densely pubescent externally, glabrous internally. Flower 5.8–7.0 cm long, white tinged with pale pink. Calyx 3-cleft, 3-horned, 4.0–4.6 × 0.4–0.9 cm, white, split nearly equal, cleft ca. 1 cm deep, teeth 1.0– 1.3 cm long, nearly equal, apex acute, slightly curved, puberulous, pubescent externally, glabrous internally. Corolla tube 2.4– 2.7 cm long, 0.6–0.7 cm wide at mouth, white tinged with pale pink, pubescent externally, villous towards mouth within and glabrous towards base; dorsal corolla lobe oblong, 3.0–3.2 × 1.3–1.4 cm, white tinged with pale pink, margin ciliate, apex hooded, subcuspidate, pubescent externally, densely towards base and sparsely towards apex, glabrous within; lateral corolla lobes oblong, 2.6–2.8 × 1.1–1.3 cm, white tinged with pink, margin ciliate, one side slightly folded, densely pubescent towards base and sparsely towards apex externally. Labellum obovate, obscurely 3-lobed, 3.0–3.1 × 2.2–2.6 cm, white tinged with pink, dark pink stripes form design at centre, margin crumbled, crenulate, slightly cleft at apex, ends overlapping, pubescent towards mouth internally. Lateral staminodes lanceolate, flattened, 0.7–0.9 × 0.2–0.3 cm, white tinged with pink, glabrous. Stamen 2.2–2.5 cm long; filament 1.1–1.1 × 0.5–0.6 cm, creamy-white, pubescent externally, glabrous within; connective glandular hairy; crest fan-shaped, obscurely 3-lobed, ca. 1.0 × 0.5 cm, white tinged with pink; anther thecae oblong, 1.2–1.3 cm long, creamy-white, base rounded, apex nearly diverging outside, glabrous; dehiscing throughout their length. Epigynous glands 2, ca. 0.6 cm long, pale yellow, apex slightly lobed, glabrous. Ovary globose, 0.5–0.7 × ca. 0.7 cm, densely pubescent externally; locules 3; ovules many on axile placentae; style ca. 4.4 cm long, glabrous; stigma cup-shaped, ca. 0.1 cm across, spotted with red, mouth ciliate, opening terminal. Infructescence 10–12 cm long, many capsules in a spike. Capsule globose, smooth walled with an apical depression, 2.0–2.5 × 2.5–3.0 cm, maroon tinged with green, pubescent externally, calyx persistent. Seeds many, angular, 0.3–0.4 × 0.3–0.4 cm, brown, aromatic, arillate; aril white. Flowering and fruiting from May to August.

Etymology:—This species is named in honour of Dr. M. Sabu, Professor at the Department of Botany, University of Calicut for his contribution to the taxonomy of Indian Zingiberaceae .

Ecology:—Found only in the mountains of Sikkim Himalaya above 1000 m.

Additional specimens examined:— INDIA. Sikkim: East Sikkim District, Pangthang, ICRI field station, 22 August 2006, V. P . Thomas 105505; 11 March 2005, E . Sanoj 92754; 23 August 2004, M . Sabu & A. K . Pradeep 92730 ( CALI!) . Sikkim Himalaya, Rungbu , May 1903, Dr. Prain’s collector s.n. ( CAL!) .

Figures

FIGURE 1. Amomum sabuanum A. a part of leafy shoot; B. ligule; C. inflorescence; D. bract; E. bracteole; F. flower; G. calyx; H. corolla lobes; I. stamen; J. labellum; K. ovary with epigynous glands and style; L. stigma; M. crosss-section of ovary; N. fruit; O. seed. Illustration by V.P. Thomas.

FIGURE 2. Amomum sabuanum A. habit; B. ligule; C. Rhizome; D. & E. inflorescences; F. bract; G. bracteole; H. flowers; I. single flower; J. calyx; K. corolla lobes; L. stamen; M. labellum; N. epigynous glands and style; O. stigma; P. fruits. Photos by V.P. Thomas.