Zingiber arunachalensis A.Joe, T.Jayakrishnan, Hareesh & M.Sabu, 2017

Joe, Alfred, Jayakrishnan, Thachat, Hareesh, Vadakkoot Sankaran & Sabu, Mamiyil, 2017, Zingiber arunachalensis (Zingiberaceae): a new species from northeastern India, Phytotaxa 309 (1), pp. 95-98 : 95-97

Zingiber arunachalensis A.Joe, T.Jayakrishnan, Hareesh & M.Sabu , sp. nov. ( Figure 1 )

Zingiber arunachalensis is similar to Z. bipinianum but differs in having non-stoloniferous rhizomes, purple lateral staminodes with creamy spots and deep purple anther crests. It also resembles Z. mizoramensis but is distinct from it in having purplish-red, narrowly ovate spikes with 6.5–8.0 cm long peduncles, narrowly ovate bracts with acuminate apices, creamy yellow corolla lobes and free, ovate lateral staminodes with acute apices. A comparison is given in Table 1.

Type:— INDIA. Arunachal Pradesh: West Kameng District, Durga Mandir, on the way to Bomdilla from Balukpong, 774 m, 30 June 2015, A. Joe & V. S. Hareesh 121844 (holotype CALI!, isotype CAL!).

Perennial, non-stoloniferous, clump forming, rhizomatous herbs. Rhizomes fleshy, little branched. Roots thick, externally light to dark brown, internally cream with an inner white circle; root tubers fusiform. Leafy shoots 70–145 cm, with 3–7 leaves when flowering; pseudostems green, glabrous towards the base and sparsely hairy towards the petiole; basal sheaths pale purple, glabrous. Ligules 5–6 mm, bilobed, apex truncate, light green, pubescent. Leaves subsessile, pulvinate, the blades ovate-lanceolate, 26.0–32.5 × 13.4–14.0 cm, adaxially green, glabrous, abaxially light green, slightly tomentose, base cuneate, apex acuminate, mid-rib abaxially pubescent, light green. Inflorescences 1–5 per plant, radical, 11–17 cm long; peduncle 4.5–8.0 cm, green, glabrous, spicate, the spikes narrowly ovate. Sterile bracts ovate, 4.5–6.0 × 3.5–4.5 cm, purplish red, apex acuminate, glabrous internally and pubescent externally. Fertile bracts narrowly ovate, 4–15 in number, each enclosing a single flower, 4.5–7.0 × 1.5–2.0 cm, purplish or purplish with green base or light green with purplish tinge, apex acuminate. Bracteoles linear-lanceolate, 4.0–4.5 × 0.8–1.0 cm, cream with a purple tinge at the apex, sparsely pubescent externally, glabrous internally, apex acute. Flowers 7.8–9.4 cm long. Calyx tubular 2.0–2.5 × 0.8–1.0 cm, unilaterally split, creamy white, externally pubescent, internally glabrous, apex trifid. Corolla tube cream, apex creamy yellow, 4.5–5.3 × c. 0.3 cm, glabrous; dorsal corolla lobe ovate-lanceolate, 3.5–3.8 × 0.9–1.3 cm, creamy with translucent veins, concave, glabrous acuminate at apex; lateral corolla lobes lanceolate, 2.0–2.7 × 0.3–0.4 cm, cream with slight yellow or orange tinge and with translucent veins, glabrous on both sides, acute or acuminate at apex, incurved soon after opening of flower; labellum ovate, 2.0–2.5 × 1.2–1.4 cm, deep violet-purple or purple with creamy yellow base and some cream dots towards the centre and lines at periphery, margin recurved. lateral staminodes ovate or narrowly ovate, 7–14 × 3–4 mm, free from labellum, apex purple with some cream dots, base cream or cream with yellow tinge, apex acute, curved inwards and attached to labellum at later stages. Stamen 2.4–2.8 cm long, filament reduced to c. 1 cm long, connective tissue glabrous, cream, anther thecae 1.0–1.2 × 0.3–0.4 cm, cream, anther crest (beak) 1.0– 1.2 cm long, deep violet-purple, wrapped around stigma, glabrous. Style filiform, white, glabrous; stigma cup-like, white, ostiole ciliate. Ovary cylindrical, creamy white, 0.7–0.9 × 0.3 cm, trilocular with axile placentation, densely pubescent; epigynous glands same or much longer than the ovary, cream, 0.8–1.6 cm long, apex pointed. Fruits unknown.

Phenology:— Flowering from June to October.

Etymology:— The specific epithet refers to Arunachal Pradesh, the Indian state where this species occurs.

Habitat and Ecology:— Zingiber arunachalensis is known only from the vicinities of Durga Mandir, on the way to Bomdilla from Balukpong, West Kameng district of Arunachal Pradesh. The plants are growing in the under storey of evergreen forests at an elevation ranges from 700– 800 m. in association with Musa arunachalensis A.Joe et al. ( Sreejith et al., 2013: 50) , M. markkuana ( Sabu et al. 2013a: 50) Hareesha et al. (2017: 283) , etc.

Conservation status:— This species is found only in a restricted area of 1–2 km 2. Further studies are needed to assess the threats and population trends to assess the conservation status. We therefore suggest this species to be listed as data deficient (DD).

Additional specimens examined (paratype):— INDIA. Arunachal Pradesh: West Kameng District, Chariduar- Tawang Road, on the way to Bomdilla from Balukpong, 600 m, 14 July 2016, T. Jayakrishnan & Nikhil Krishna 150201 (CALI!).

Figures

FIGURE 1. Zingiber arunachalensis. A. habit. B. rhizome. C. portion showing leaf bases and ligules. D. basal part of plant showing inflorescences. E–F. flower showing the variations in labellum color pattern. G. single flower. H–I. bract showing variations in color pattern. J. portion of flower showing curved floral parts at later stage of flowering. K. calyx. L. corolla lobes. M. labellum with lateral staminodes. N. ovary with epigynous glands and basal portion of style. O. stamen with style and stigma. Photos by Alfred Joe and T. Jayakrishnan.