Begonia kekarmonyingensis Taram, D.Borah & M.Hughes, 2021

Taram, Momang, Borah, Dipankar & Hughes, Mark, 2021, Begonia kekarmonyingensis (Begoniaceae), a new species from Arunachal Pradesh, Northeast India, Phytotaxa 494 (3), pp. 268-272 : 270-271

Begonia kekarmonyingensis Taram, D.Borah & M.Hughes sp. nov., § Platycentrum ( Figs. 1 & 3 )

Diagnosis:—The new species is similar to Begonia cathcartii in having pseudo-opposite leaves subtending the inflorescence, and having tepals which are pilose abaxially. It differs in having denser hairs on the upper leaf surface which are much shorter, giving the leaf a rough appearance (not glossy); tepals which although pilose abaxially have shorter and more sparse hairs, and sparser and shorter hairs on the petioles and peduncles; it is also a smaller plant i.e. less than 30 cm (vs. up to 60 cm tall) and has shorter internodes i.e. less than 3 cm long on the erect stem (vs. up to 23 cm). It differs from B. menglianensis in having cauline leaves on the inflorescence (vs. absent), white ovaries with sparse red pilose hairs (vs. red or green ovaries which are glabrous), sparser and shorter white (vs. denser and longer red) pilose indumentum on the petioles and veins on the lower leaf surface, and leaves with an acuminate (vs. rounded to acute) apex.

Type:— INDIA, Arunachal Pradesh, Siang district, Babuk , Kekar Monying , 15 February 2020, M . Taram & D.Borah 2094 (Holotype: ASSAM, Isotype : ARUN) .

Plant monoecious, perennial, rhizomatous, 15–30 cm tall. Stem erect when flowering, branched, 4–10 cm long, 5– 8 mm thick, internodes 0.3–3 cm long, longest on flowering stems. Stipule deciduous, slightly membranous, triangular 8–12 × 4–6 mm, sparsely pubescent, later glabrescent, greenish-white, margin entire, apex cuspidate, cusp ca. 3–4 mm long. Leaves 6–12 per plant. Petiole red, terete, 4–14 cm long, 3–5 mm thick, white pilose, ca. 0.2 mm long. Blade green, broadly ovate, 15–17 × 4–11 cm, strongly asymmetric, puberulous on both surfaces (adaxial surface hairs white, abaxial surface hairs pink, denser on veins); venation palmate, 6–7 veined; cordate at base, lobes overlapping slightly, margin irregularly serrulate, apex acuminate. Inflorescence axillary, 7–15.5 cm long, 1 or 2 branched, subtended by two pseudo-opposite cauline leaves, peduncles red, white pilose, 2–4 mm in diameter. Bracts ovate, navicular, 6–10 × 4–7 mm, sparsely hairy at the base adaxially, margin entire. Flowers 3–6 per inflorescence (a branch comprising 2 staminate flowers with a pistillate flower); protandrous. Staminate flower: pedicel red, 5–10 mm long, pilose with deep pink hairs, tepals 4, outer 2 larger, white, slightly red at the base, broadly ovate, 11–15 × 11–15 mm, outside covered with red hispid hairs towards the base; inner 2 smaller, white, ovate, 11–13 × 9–10 mm, glabrous; androecium 4–6 mm long, 4–10 mm in diameter; stamens 80–120, filaments 2–3 mm long; anthers yellow, obovate, 0.9–1.1 mm long, apex rounded. Pistillate flower: pedicel red, 2–5 mm long; corolla 15–19 mm in diameter; tepals (4–)5, white, outer 2 ovate, 10–15 × 6–13 mm, covered with red hispid hairs at the base, inner 2–3 similar to the outer tepals in shape and size, glabrous; styles 2, free, 3–8 mm long, with a convoluted stigmatic band, yellow. Ovary 4–5 × 3–4 mm excluding the wings, pinkish white, hispid, three-winged, longest wing 5–8 mm wide, lateral wings 1–2 mm wide; locules 2, placenta 2 per locule.

Etymology:—Named after Kekar Monying, a place of historical significance and a tourist attraction, from where the type of new species is collected.

Phenology:—Flowering and fruiting from February-April.

Distribution and habitat:— Begonia kekarmonyingensis is so far considered endemic to the type locality of Kekar Monying in Arunachal Pradesh (Siang belt). It grows near streams, waterfalls and in rock crevices of the moist shaded areas by the roadside.

Conservation status and ecology:—The species was found in one location with ca. 100 individuals.The area was on private land, not designated as a protected area. It grows in association with Henckelia mishmiensis (Debb. ex Biswas) D.J.Middleton & Mich.Möller (Gesneriaceae) , Boeica fulva C.B.Clarke (Gesneriaceae) , Elatostema sp. (Urticaceae) , Rhynchotechum parviflorum Blume (Gesneriaceae) , R. vestitum Wall. ex C.B.Clarke (Gesneriaceae) , Asplenium sp. (Aspleniaceae) , Tacca integrifolia Ker Gawl. (Taccaceae) , Mycetia sp. (Rubiaceae) and Wallichia oblongifolia Griff. (Arecaceae) . Given the single location and lack of protection for the area, we assessed B. kekarmonyingensis to belong to the Vulnerable IUCN category under criteria VU D1 & D2 (IUCN Standards and Petitions Subcommittee, 2017).

Figures

FIGURE 1. Begonia kekarmonyingensis Taram, D.Borah & M.Hughes. A, Habit; B, Stipule; C,D Leaves; E, buds and bracts; F,G. Male flower (front and side view); H,I. Female flower (front and side view); J,K. Androecium; L. Gynoecia. A–L from M.Taram & D.Borah 2094

FIGURE 3. Map showing the distribution of Begonia kekarmonyingensis, B. cathcartii and B. menglianensis.