Hedychium ziroense V.Gowda & Ashokan, 2019

Ashokan, Ajith & Gowda, Vinita, 2019, Hedychium ziroense (Zingiberaceae), a new species of ginger lily from Northeast India, PhytoKeys 117, pp. 73-84 : 73

Hedychium ziroense V.Gowda & Ashokan sp. nov. Fig. 2

Diagnosis.

Based on inflorescence shape and floral characters such as flower colour, relative length of filament to the labellum, relative length of corolla lobes to lateral staminodes and labellum, Hedychium ziroense V.Gowda & Ashokan, sp. nov. is morphologically similar to H. griersonianum R.M.Sm., H. ellipticum Buch.-Ham. ex Sm., H. gomezianum Wall. and H. yunnanense Gagnep., but it can be easily distinguished from the aforementioned species by lamina length (up to 60 cm long in H. ziroense vs. 40 cm or less in H. griersonianum , H. ellipticum , H. gomezianum and H. yunnanense ), bract length (4 cm or more in H. ziroense and less than 4 cm in H. griersonianum , H. ellipticum , H. gomezianum and H. yunnanense ), number of flowers per cincinnus (2-3 flowered in H. ziroense vs. 1-flowered in H. griersonianum , H. ellipticum , H. gomezianum and H. yunnanense ), relative lengths of bract and calyx (bract always longer than calyx in H. ziroense vs. bract length equal or less compared to calyx in H. griersonianum , H. ellipticum , H. gomezianum and H. yunnanense ) and anther colour (orange in H. ziroense vs. crimson in H. griersonianum , orange-red in H. ellipticum , red in both H. gomezianum and H. yunnanense ), (Figs 2 , 3 and 4 ; Table 1 ).

Type.

INDIA. Arunachal Pradesh, Lower Subansiri District, about 5 km before Ziro town along the Itanagar-Ziro road. Terrestrial herbs on the edge of sub-tropical broad-leaved evergreen forest, 27°32'13.19"N, 93°47'35.70"E, 1717 m a.s.l., A. Ashokan, VG2017-AR1989, 08 September 2017 (flowering). Holotype: BHPL!; isotypes: ARUN!, BHPL!, CAL!. Fig. 2 .

Description.

Terrestrial, rhizomatous herb up to 1.6 m tall; rhizome branching parallel to leaf distichy, pale brown externally, creamy white internally; leafy shoot slanting with an erect inflorescence; basal sheath pinkish-red. Leaves subsessile; sheath purplish-red; ligule 1.8-2.3 cm wide, ovate, glabrous, purplish-red; lamina 35-60 × 13-17 cm, elliptic-lanceolate, glabrous, dark green (adaxial) and pale green (abaxial); acumen 1.5-3.0 cm long, ends in a small caducous appendage; base rounded, red protrusion at the junction of ligule and leaf base. Inflorescence 16 × 8 cm, dense-spike, erect, cylindrical; rachis pubescent, remains more hidden due to overcrowding of bracts and flowers; bracts 4.0-4.5 × 1.0-1.2 cm, elliptic, glabrous, green, tinged with red, folded, involute, 2-3 flowered; bracteoles 1.0-1.5 cm long, tubular, pubescent, greenish-red. Flowers 11.5-12.5 cm long, ascending, white (when fresh), turn creamy white the next day, many flowers open simultaneously, mildly fragrant in the daytime and strongly fragrant at night; calyx 2.8-3.2 cm long, tubular, translucent, 3-toothed, slightly hairy at tip; floral tube 4.7-5.0 cm long, glabrous, curved, greenish-yellow; corolla lobes linear, curled, orientated downwards, glabrous, light green; dorsal lobe 4.2-4.5 cm long, linear, curled, glabrous, beaked at tip, embracing the filament and anther in the bud stage, light green; lateral lobes 4.0-4.3 cm long, linear, curled (single curl), non-beaked at tip, glabrous, light green; lateral staminodes 3.5-4.0 cm long, widest part 0.5 cm, narrowly oblanceolate, one edge linear, obtuse, unguiculate, upper halves reflexed backwards, positioned acute (<70°) with respect to labellum, white, light yellow towards base; labellum 3.5-4.0 × 1.0-1.5 cm, elliptic, glabrous, white with light yellow blotch, deeply bilobed, canaliculate, gradually clawed; lobes acute, upper halves reflexed backwards; sinus 1.5-2 cm deep; claw 1.0-1.3 × 0.2-0.3 cm; filament 5.5-6.0 cm long, slightly arching, deeply grooved on one side, pale orange, bright orange towards tip; anther 0.9-1.2 cm long, linear, basifixed, orange; thecae 2, split longitudinally; connective 0.1-0.2 cm long, bright orange; stigma 0.1 cm wide, cup-shaped, hairy at tip, exserted from the anther by at least 0.1 cm, green; style 11.5-12 cm long, filiform, white, greenish towards tip; epigynous nectaries 0.2-0.25 cm long, glabrous, yellow; ovary 0.3-0.4 × 0.2-0.4 cm, barrel-shaped, pubescent, creamy orange externally; placentation axile; ovules spherical, creamy white. Fruit not seen.

Distribution and habitat.

This species is known only from collection along road banks on the Itanagar-Ziro road, Lower Subansiri District, Arunachal Pradesh at an elevation of more than 1700 m.

Phenology and ecology.

Flowering from August to September. Flowers mildly fragrant during the day and prominently fragrant at night indicating that this species may be pollinated by nocturnal pollinators.

Sub-tropical broad-leaved evergreen forest; canopy partially shaded; soil black, clay loam; Average temperature: 25 ± 2 °C; Humidity:> 98%; Average rainfall: ~3000 mm.

Other Hedychium in the vicinity: H. coccineum Buch.-Ham. ex Sm., H. speciosum var. gardnerianum (Ker Gawl.) Sanoj and M.Sabu, H. stenopetalum Lodd. and H. wardii C.E.C.Fisch. Except for some H. speciosum var. gardnerianum , all other Hedychium were fruiting at the time of collection.

Etymology and vernacular name.

The specific epithet, " ziroense ", is derived from the type locality ‘Ziro’, the closest town to where the species was found. The town of Ziro is the headquarters of Lower Subansiri District, Arunachal Pradesh. Ziro is also the name of the native tribal inhabitants of the valley much before the arrival and subsequent colonisation of Apatani tribe (Ngunu Ziro pers. com.). In Apatani language, members of Hedychium are known by the common name “papi” ( Bouchery 2016).

Conservation status and IUCN preliminary assessment.

At the time of collection, the area comprising this population was under threat due to the ongoing resurfacing and widening of the Ziro-Hapoli-Yazali-Kimin road. As this species is known only from the type locality, we categorise it as data deficient (DD) following the IUCN guidelines ( IUCN Standards and Petitions Subcommittee 2017).

Figures

Figure 2. Hedychium ziroense V. Gowda & Ashokan, sp. nov. A Habitat B Habit C Inflorescence D Flower E Floral dissection a Bract b Bracteole c Unopened bud d Calyx e Dorsal corolla lobe f Lateral corolla lobe x 2 g Labellum h Lateral staminode x 2 i Floral tube j Filament k Anther l Stigma m Style n Epigynous nectary x 2 o Ovary. Photographed by Ajith Ashokan.

Figure 3. Comparison of Hedychium ziroense and H. griersonianum. A, B Shoot and inflorescence of H. ziroense sp. nov. C H. griersonianum D Holotype of H. griersonianum R. M. Sm. Photo Credits: A, B Ajith Ashokan C Andrew Grierson. © Royal Botanic Garden Edinburgh 2018; D http: // data. rbge. org. uk / herb / E 00265100 © Royal Botanic Garden Edinburgh 2018.

Figure 4. A Hedychium griersonianum B Inflorescence of H. yunnanense (flower in the inset) C Inflorescence of H. ellipticum D Inflorescence of H. gomezianum E Flower of H. ziroense F Flower of H. ellipticum G Flower of H. gomezianum. Photo Credits: A Andrew Grierson. © Royal Botanic Garden Edinburgh 2018; B Leslie Brothers. © United States National Herbarium (US); C, E. Ajith Ashokan; D, F, G Preeti Saryan.