Henckelia umbellata Kanthraj & K.N.Nair, 2020

Henckelia umbellata Kanthraj & K.N.Nair View in CoL , sp. nov. Fig. 1 View Fig

The new species can be easily distinguished from its congeners by its flowers borne in umbels. H. umbellata superficially resembles H. longisepala (H.W.Li) D.J.Middleton & Mich.Möller mainly in the large paired involucral bracts enclosing the flowers. But it differs from H. longisepala in having 4–6-flowered umbellate inflorescences (vs. 3-9-flowered umbel-like cymes); fused, narrowly triangular, acuminate sepals (vs. free, spatulate-linear, obtuse sepals) and anther connective without any appendage (vs. connective with one appendage abaxially).

Type: INDIA, Arunachal Pradesh, Kra Daadi district, near Yangte village , 27̊ 44' 7.23" N, 93̊ 38' 8.18" E, 1295 m, 12.09.2018, A. S . Kanthraj 319888 (holo LWG!; iso CAL!) .

Perennial caulescent herbs. Stems erect to sometimes decumbent, 30–150 cm long, scarcely branched, rooting from the woody base, internodes 6.5–11 cm long, cylindrical, green to dark purplishbrown, indumentum white with reddish-brown tips. Leaves opposite, usually in unequal pairs with a large and a slightly smaller leaf; petioles 3–11 cm long, 1–3 mm broad, green-brownish, sparsely hairy with red-brown hairs; lamina ovate to ellipticoblong, 8–18 × 4–8 cm, apex acuminate, margins crenate-serrate, densely brown pubescent, base oblique, upper surface with many white pilose hairs, lower surface with white and reddish-brown pilose hairs and many white sessile glands; lateral veins 8–12 pairs, more prominent and clothed with red-brown hairs on lower surface. Inflorescence axillary, umbellate, 4–6-flowered; peduncles 3–6 cm long, stout, terete, green to dark purple, densely hairy; bracts 2, free, enclosing the flower buds, broadly ovate, 2.8–3.5 × 2.4–2.6 cm, apex acuminate, shallowly crenate towards apex, green with prominent purplish veins, with brown hairs outside, glabrous inside, caducous; pedicels enclosed within the bracts, 1.2–2.2 cm long, stout, greenish–white, glabrous. Calyx 5-lobed, fused almost up to middle, 3.5–3.7 cm long, purplish-white; tube 1.7–2.0 cm; lobes narrowly triangular, 1.7–1.8 cm long, acuminate, white pilose hairy outside, glabrous inside. Corolla infundibuliform, 5–7 cm long, tube slightly curved downward, bluish purple, abruptly tapering towards the whitish base, sparsely hairy out, bilabiate, 5-lobed, lower lobes 3, 0.8–1.2 × 1.0– 1.4 cm, upper lobes 2, 1.0–1.5 × 1.5–1.8 cm; lobes entire, rounded, bluish purple, throat with yellow, purple markings and dark purple-brown stripes, inner surface with many glandular trichomes. Stamens 2; filaments inserted c. 2.5 cm above the base of the corolla, 1.0– 1.2 cm long, geniculate, white, sometimes with yellow marking at geniculation, clothed with a tuft of glandular hairs near the connective and below the geniculation; anthers coherent face to face, 2.5–4 × 1.5–2.2 mm, creamy with a purple blotch, glabrous. Staminodes 2, on either side of the stamen, inserted c. 2 cm from base of the corolla, c. 1 cm long, whitish, sparsely hairy, antherodes incurved, greenish, glabrous. Disc tubular, c. 7 mm high, shallowly 5- lobed, greenish; ovary 20–23 × 1.5–2 mm, green, glabrous; style 1.2–1.5 cm long, whitish, glandular pubescent; stigma upper lip absent or very obscure, lower lip deeply bilobed, 3–3.5 mm long, 4.5–7 mm wide, papillose, purplish-white. Capsules 10– 16.5 cm long, linear, green, orthocarpic, without persistent disc and calyx. Seeds broadly ellipsoid, 0.4–0.47 × 0.18–0.23 mm, dark brown, pitted.

Flowering & fruiting: Flowering from August to October and fruiting from September to November.

Habitat: On muddy slopes and shady places along moist tropical forest margins at elevation of 770 to 1700 m. The species occurs sporadically in small patchy populations with a few to many plants.

Distribution: So far known only from Arunachal Pradesh, India ( Fig. 2 View Fig ).

Etymology: The specific epithet denotes the characteristic umbellate inflorescence of this species.

Specimens examined: INDIA, Arunachal Pradesh, Kra Daadi district, near Choba village , N 27 ̊45'30.6", E 93 ̊36’36.72", 1003 m, 12.09.2018, A. S . Kanthraj 319892; near Yangte village , N 27 ̊44'2.63", E 93 ̊38'15.04", 1288 m, 19.09.2019, A. S . Kanthraj 321076; Palin-Nyapin, near Yangte village , N 27 ̊44'8.08", E 93 ̊38'7.37", 1286 m, 12.09.2018, A. S . Kanthraj 319890 ( LWG); Kurung Kumey district, 15 km before Koloriang town , N 27 ̊52'39.05", E 93 ̊26'59.67", 772 m, 19.09.2019, A. S . Kanthraj 321087; Koloriang, N 27 ̊54'12.13", E 93 ̊22'29.27", 843 m, 20.09.2019, A. S . Kanthraj 321088; Yarte, N 27 ̊54'12.13", E 93 ̊22'29.27", 793 m, 19.09.2019, A. S . Kanthraj 321085 ( LWG); Lower Subansiri district, near Deed , N 27 ̊33'30.63", E 93 ̊41'8.16", 1579 m, 18.09.2019, A. S . Kanthraj 321074; New Palin to Deed , N 27 ̊38'53.88", E 93 ̊37'36.48", 1310 m, 13.09.2018, A. S . Kanthraj 319893; Ziro, N 27 ̊32'28.91", E 93 ̊47'35.99", 1695 m, 21.09.2019, A. S . Kanthraj 321089 ( LWG) .

Conservation status: The species has so far been found at seven localities in three districts in Arunachal Pradesh. Preliminary surveys revealed that the species occurs in small fragmented populations, each with four to fifteen mature individuals. The expansion of the National Highway 713, which connects Joram and Koloriang via Palin in Arunachal Pradesh, is a potential threat to the natural habitat and populations of this species. Further surveys and studies in other likely areas of its occurrence are needed to assess the conservation status of the new species. Based on the present data, it is provisionally assessed here as “Data Deficient ( DD)” under the IUCN Red List Categories and Criteria (version 3.1) ( IUCN 2001, 2012, 2019).

Notes: Henckelia umbellata belongs to the group of NE Indian and Himalayan species of Henckelia with caulescent habit, internodes with leaves in whorls of 2 or 3, and orthocarpic capsules. H. longisepala with which H. umbellata shares morphological similarities has an isolated geographic distribution in China and Laos ( Li, 1983; Wang, 1984; Wang et al., 1988; Weber et al., 2011) and in Vietnam (Bui et al., this issue). Although H. umbellata shows resemblances with H. longispepala and H. urticifolia , its true phylogenetic affinities with other congeners need to be examined further (see Table 1).