Amomum nimkeyense M.Sabu, Hareesh, Tatum & A.K.Das, 2018

Sabu, Mamiyil, Hareesh, Vadakkoot Sankaran, Mibang, Tatum & Das, Arup Kumar, 2018, Amomum nimkeyense (Zingiberaceae), a new species from Arunachal Pradesh, northeastern India, Phytotaxa 340 (2), pp. 197-200 : 197-198

Amomum nimkeyense M.Sabu, Hareesh, Tatum & A.K.Das sp. nov. ( Figure 1 )

Amomum nimkeyense is similar to A. subulatum , but differs from the latter by having ovate to linear-obovate leaf lamina with equal base, the abaxial surface densely pubescent, a 8−9 mm long pubescent ligule, inflorescence bracts reddish towards the base and golden brown at the middle, and bracteoles pale yellowish brown with a median red band, a white-pink tinged calyx, pubescent corolla tube, obovate labellum lacking lateral staminodes, a glabrous ovary and a capsule with small wings towards the apex.

Type:— INDIA. Arunachal Pradesh: Lohit District, Tidding, On the way to Hayuliang from Tezu, 16 May 2017, M. Sabu & V. S. Hareesh 149378 (holotype CALI!, isotype CAL!).

Rhizome non-stoloniferous, 5 − 6 × 5 − 7 cm thick, ovate, ivory-coloured at centre and pale pink towards margin, length/ breadth ratio c. 1, covered with chartaceous, pubescent scales. Leafy shoots 150 − 200 cm tall, clump-forming; sheath, reddish brown, margin membranous and glabrous, pubescent externally. Leaves 5 − 7 per shoot; lamina ovate to linear-obovate, 31 − 60 × 16 − 27 cm, base acute to cuneate, apex acute to acuminate, margin slightly wavy, lamina dark green, glabrous above, pale beneath, densely pubescent below; veins raised; midrib densely pubescent below; petiole 2 − 9 cm long, pale green, pubescent; veins prominent above. Ligule bi-lobed, 8 − 9 mm long, thick, apex rounded, densely pubescent externally. Inflorescence 9 − 10 cm long, 2-flowered, arise from rhizome just below aerial stem; peduncle 4 − 5 cm long. Outer bract ovate, 1 − 2.5 × 1 − 2 cm, reddish towards base and golden brown at middle, membranous, margin and outer surface pubescent, glabrous within, apex acute, with a c. 2 mm long cusp; inner bract, ovate, 3.8 × 2 cm, reddish towards base and golden brown at middle, membranous, margin and outer surface pubescent, inner surface glabrous, apex with a 4 mm long cusp. Bracteole non-tubular, 3 − 3.5 × 1.3 − 1.5 cm, oblong with a c. 2 mm long apical cusp, pale yellowish brown with a median red band, pubescent externally, glabrous internally. Flower 5.5 − 6 cm long, yellow, borne singly from each bract. Calyx 3-lobed with subulate horns, 3.4 − 3.5 × 1.5 − 1.7 cm, membranous, horn up to 7 mm long, white tinged with pink, pubescent externally, glabrous within. Corolla tube 2.8 − 3 cm long, 5 − 6 mm wide at mouth, white tinged with pink, pubescent externally; dorsal corolla lobe oblong, 3.3 − 3.5 × 0.9 − 1.1 cm, cream, margin pubescent, hooded at apex, apical cusp 6 − 7 mm long, glabrous; lateral corolla lobes lanceolate, 3 − 3.3 × 0.6 − 0.7 cm, margin pubescent, apex rounded, pubescent. Labellum obovate, entire, 2.8 − 3 × 2.2 − 2.4 cm, cream with a median deep yellow band towards tip and pinkish towards base, margin crenulate, entire, pubescent towards base internally. Lateral staminodes absent. Stamen 2.3 − 2.5 cm long; filament 0.8 − 0.9 × c. 0.35 cm, white, glabrous within; connective glabrous; crest entire, cream-coloured, 1 − 1.1 × 0.4 − 0.5 cm, yellow, glabrous; anther thecae oblong, 1.1 − 1.2 cm long, creamy-white, base acute, apex nearly rounded, diverging outside, apex and base glabrous; dehiscing longitudinally. Epigynous glands 2, 4 − 5 cm long, creamy-white, apex obtuse, glabrous. Ovary globose, 0.5 − 0.6 × 0.6 − 0.7 cm, glabrous externally; locules 3; ovules many on axile placenta; style c. 5.4 cm long, glabrous; stigma subglobose, c. 0.1 cm across, white, mouth ciliate, opening terminal. Capsule ovate, slightly winged at apex,1.8 − 2 × 1.4 − 1.5 cm, glabrous.

Phenology:— May to September.

Etymology:— The specific epithet nimkeyense denotes originating from Nimke, a sacred place of the spirits of Miju Mishmi tribe of Lohit District.

Habitat and Ecology:— Amomum nimkeyense , is known only from Tidding, Lohit valley, on the way to Hayuliang from Tezu, Lohit District of Arunachal Pradesh. The plants are growing in the moist sloping areas in association with Impatiens citrina Hook.f. (1905: 17) , I. siculifer Hook.f. (1908: 246) , Maianthemum sp. , Pollia sp., and Elatostema sp.

Conservation status:— As the occurrence of this new taxon is found in highly restricted in 1–2 km 2 area, the species is likely to fall within a category of threat. Probable threat to its existence in this locality due to natural calamities and other developmental activities which may lead to loss of its natural habitat. Thus, based on the present knowledge and available data, conservation status is assessed as Data Deficient (DD).

Figures

FIGURE 1. Amomum nimkeyense. A. habit. B. lamina. C. ligule. D–F.basal part of plant showing inflorescences. F. inset T.S. of rhizome. G. inner bract. H. bracteole. I. single flower. J. calyx. K. corolla lobes. L. labellum. M. stamen. N. ovary with epigynous glands and basal portion of style. O. C.S. of ovary. P.stigma. Q. fruit. Photos by M. Sabu and V.S. Hareesh.