Henckelia siangensis Taram, D.Borah & Tag, 2020

Taram, Momang, Borah, Dipankar, Taku, Ojar & Tag, Hui, 2020, Henckelia siangensis (Gesneriaceae): a remarkable new species from Northeast India, PhytoKeys 160, pp. 1-6 : 1

Henckelia siangensis Taram, D.Borah & Tag sp. nov.

Type.

India. Arunachal Pradesh: East Siang District, Pasighat, 28°13'54"N, 95°13'19"E; 375 m asl., 26 April 2019, Ojar Taku and Momang Taram 05001 (holotype: ASSAM; isotype: ARUN). (Fig. 1 )

Diagnosis.

The species is remarkably different from all other species of Henckelia by its 5-winged calyx and elliptic-ovate calyx segments. It is superficially similar to H. calva (C.B.Clarke) D.J.Middleton & Mich. Möller in glabrous stem and petiole as well as lanceolate bracts, but can be easily distinguished by ovate to lanceolate lamina with denticulate to serrulate margins (vs. elliptic to oblong- elliptic with entire to sub-entire and ciliate margin), peduncle 0.4-0.8 cm, glabrous (vs. 2-3 cm long, glabrescent), bracts persistent (vs. deciduous), calyx segments elliptic to ovate, raised at margins forming wings (vs. narrowly triangular to lanceolate), corolla glandular pubescent inside (vs. glabrous) and glandular hairy style (vs. puberulent).

Erect perennial herb, caulescent, 15-40 cm high, stems branched; mature stem terete, ca. 0.5 cm across, glabrous, young stem reddish brown, cylindrical. Leaves decussate; petiole terete, glabrous, slightly ridged at base, 1-6 × 0.1 cm, fleshy; lamina ovate to lanceolate, 7-10 × 2.5-4.5 cm, oblique-obtuse base, acute to shortly acuminate at apex, margin denticulate-serrulate, sparsely hirsute on both surfaces, hairs hyaline, dark green above, pale green below; secondary veins 6-10 pairs, sub-opposite, obscure above, raised beneath. Inflorescence axillary, 1 flowered cymes; peduncle 0.4-0.8 cm long, glabrous; pedicel glabrous 1.8-2.3 long, ca. 0.1cm thick; bracteoles 2, glabrous, green, opposite to sub opposite, ovate to lanceolate, 4-7 × 2-4 mm, apex acute, margin entire to sub entire. Calyx green, campanulate, 5 winged, raised at the fusion of the lobes, splitting with maturity, later turning 5 lobed up to below middle of the tube, glabrous, veins obscure, tube 0.6-0.7 cm long; calyx segments 2.0-2.3 × 0.6-1.1 cm, elliptic-ovate, margin entire, apex acute. Corolla 4.5-5 × 1.4-1.8 cm, bright yellow with three dark yellow and maroon stripes per lobe near throat, more prominent on lower lip, glabrescent outside, glandular pubescent inside (dense within tube), distinctly 2 lipped, lips divergent; upper lip 2-lobed, equal, broadly ovate, 0.4-0.6 cm × 0.5-0.7 cm, apex round, margin entire; lower lip 3-lobed, lobes sub-equal, broadly ovate, 0.7-1 × 0.5-0.6 cm, apex round, margin entire; tube 2.8-3.5 × 1.3-1.7 cm. Stamens 2, inserted 2-2.3 cm above corolla base, anthers and top of filaments maroon, glandular pubescent; anthers 0.2-0.3 × 0.1-0.2 cm, cohering face to face; filaments 0.8-1.5 × 0.1 cm, geniculate near base, knee dark pink-maroon. Staminodes 3, lateral staminodes 2, divergent (sometimes coiled), 0.4-0.7 cm long, hirsute, maroon, central staminode white, antherodes white-green, 0.2-0.3 cm long. Pistil 2.8-3.6 cm long; style glandular hairy, 1.5- 1.9 cm long; stigma chiritoid, lower lip 2 lobed, lobe apex acute to obtuse; disc yellow, undulate-annular, ca. 0.1 cm high. Ovary green, glabrous to glabrescent, 1.6-2 × 0.15 cm. Capsules not seen.

Phenology.

Flowering: April and fruiting: September.

Etymology.

The species is named after the type locality, the Siang valley.

Vernacular name

(assigned here). Libe lirak Appun (in Adi language)

Distribution.

So far only known from East Siang district of Arunachal Pradesh, India.

Habitat and ecology.

It grows in moist shady places in rock crevices in association with Henckelia mishmiensis (Debb. ex Biswas) D.J.Middleton & Mich. Möller, Aeschynanthus superbus C.B.Clarke, Begonia josephii A.DC., B. burkillii Dunn., Elatostema sessile J.R.Forst. & G.Forst., Pilea umbrosa Blume, Nephrolepis cordifolia (L.) C.Presl., Selaginella sp. etc.

Figures

Figure 1. Henckelia siangensis. A flowering stem B flower front view C flower side view (arrow indicates the bracteoles) D winged calyx (arrow indicates the wings) E dissected calyx segments F dissected corolla G stamens and staminodes H pistil (Photographs by Momang Taram).