Whytockia arunachalensis Taram, D.Borah & Tag, 2022

M., Taram, D., Borah, H., Tag, M., MÖller & Weber, A., 2022, Whytockia (Gesneriaceae), a new generic record for India, based on a new species, W. arunachalensis, from Arunachal Pradesh, India, Rheedea 32 (1), pp. 18-29 : 22-28

Whytockia arunachalensis Taram, D.Borah & Tag , sp. nov. Figs. 1–4

Whytockia arunachalensis can be distinguished from all other species in the genus (particularly the whiteflowered W. sasakii and W. tsiangiana ) by its relatively large habit and large leaves (the largest in the genus; up to 18 × 10 cm vs. W. sasakii 10.5 × 4.5 cm; W. tsiangiana 13 × 4.5 cm), by the dense and c. 1 mm long stem indumentum (vs. W. sasakii glabrescent; W. tsiangiana puberulent), the dense c. 1 mm, thin, and erect leaf indumentum (vs. sparsely puberulent in both species), and calyx with uniform 1.5 mm long indumentum (vs. asymmetric calyx indumentum in both species). From W. sasakii and W. tsiangiana , the new species can be further distinguished by the puberulent outer side of the corolla (vs. glabrous in both species), the presence of two rows of pinkish glandular hairs on the corolla tube floor in Whytockia arunachalensis (vs. two rows of yellow glandular hairs in both species), glandular unicellular hairs around the tube opening (vs. limited to lateral patches in both species).

Type: INDIA, Arunachal Pradesh, East Siang district, Rottung , N 28°07’56.1'’, E 95°07’46.5'’, around 200 m, 08.07.2021, Taram 9699 (holo CAL!; iso ASSAM!).

Perennial caulescent herbs. Stems 20–60 cm tall, 0.5–1 cm in across, shortly hairy (c. 1mm long), hairs white-hyaline, erect, usually not branched, base decumbent, rooting at lower nodes, dirty green to dark purple in fresh material, internodes 4–15 cm long. Leaves opposite, anisophyllous, in each pair very unequal in size, sessile, adaxially yellowishgreen, abaxially pale green; dense white hyaline indumentum of c. 1 mm long uniform uniseriate, erect, eglandular hairs on both surfaces; larger leaves ovate, 8–18 × 5–10 cm, asymmetrical, base oblique to cordate, apex acute to acuminate, margins entire or sub-entire, lateral veins sub-opposite, 11–13 pairs; smaller leaves ovate 1.5–3 × 1–1.5 cm, base cuneate, apex acute, margin sub-entire to serrate, lateral veins sub-opposite, 2–3 pairs. Inflorescences 1(–2) with pair-flowered cincinni, axillary, emerging from the axils of the larger leaves, uppermost one often pseudo-terminal, ebracteolate, lax, shortly hairy, 6–10 cm long, each with 3–12 flowers, flowers in pairs; peduncles 1.5–4 cm long, pedicels 0.6–1 cm long, both covered in short (c. 1 mm) erect glandular hairs. Calyx segments free to base, 5 (rarely 6), imbricate, lanceolate, 0.3–0.6 × 0.1–0.2 cm, outer surface with long, perpendicularly spreading eglandular hairs, glabrous inside. Corolla plain white, zygomorphic, short tubular infundibuliform, 1.8–2.3 cm long, face 1.2–1.4 cm wide, tube 0.8–1.5 cm long, mouth c. 0.4 cm high, c. 0.25 cm wide, slightly curved downwards, puberulent outside, glandular unicellular hairs (0.3–0.7 mm long) around the tube opening and towards the base, inner side of tube with two rows of pink, clavate to capitate hairs on the floor and two rows of smaller white glandular hairs to the left and right along the tube floor from corolla base to mouth; limb 2-lipped; adaxial lip 2- lobed, lobes c. 0.2 × 0.2 cm, round, abaxial lip 3- lobed, lobes 0.2–0.6 × 0.2–0.4 cm, ovate to orbicular. Stamens 4, up to 0.4 cm, adnate to corolla tube near base, included, didynamous; filaments of abaxial (anterior) stamens 0.2–0.3 cm long, those of adaxial (posterior) stamens 0.1–0.2 cm long, all 0.5 mm thick, strongly twisted near middle, glabrescent; anthers 0.1 × 0.1 cm, dorsifixed, confluent at apex, coherent in pairs, long papillose on the back. Staminode 1, linear, c. 0.1 cm long, glabrous. Disc annular, c. 0.5 mm high, orange. Pistils 0.6–0.9 cm long; ovary globose, c. 0.2 × 0.2 cm, glabrous, 2-loculed with a complete transversal septum; placentae 2, axile, 2-cleft, each of the 4 ovule-bearing arms projecting inwards; style 0.4– 0.6 cm long, sharply set off from ovary, bent downwards near tip, glabrescent; stigma bilobed, lobes placed laterally, 0.1– 0.1 cm long. Ripe fruits, dehiscence and seeds not known. Immature seeds brown, unappendaged.

Flowering & fruiting: Flowering from July to August, fruiting from August to September.

Habitat: The plants grow in moist shady places near stream sides in association with Rhynchotechum parviflorum Blume and Henckelia urticifolia (Buch.- Ham. ex D.Don) A.Dietr. ( Gesneriaceae ), Impatiens siangensis Gogoi ( Balsaminaceae ), Phrynium pubinerve Blume ( Marantaceae ), Hydrocotyle javanica Thunb. ( Araliaceae ), Musa sp. ( Musaceae ), Elatostema sp. ( Urticaceae ), and Strobilanthes sp. ( Acanthaceae ).

Distribution: Thus far, only two populations have been observed, one in Rottung and another in Boleng, in the East Siang and Siang districts of Arunachal Pradesh and roughly 40 km apart as the crow flies.

Etymology: The specific epithet refers to the state of Arunachal Pradesh, where this species was discovered.

Additional specimens examined: INDIA, Arunachal Pradesh, Siang district, Boleng , around 500 m, 15.07.2021, Taram 9721 ( ASSAM) .

Conservation status: Two localities of the new species are known so far, in Boleng and Rottung, situated c. 40 km apart. One population (with more than 100 mature plants) is located near the roadside, which is under potential threat from road widening, which is ongoing in several districts of Arunachal Pradesh. The other population (with more than 250 mature plants) was found near a stream, with no immediate threats. However, none of the populations is in a protected area. Given the generally inaccessible terrain around and between the localities, it is difficult to ascertain whether more suitable habitats exist nearby in which more populations of the new species may be discovered. Therefore, we assess the conservation status for W. arunachalensis provisionally as Data Deficient ( DD) ( IUCN, 2022).

Figures

FiG. 1. Whytockia arunachalensis Taram, D.Borah & Tag: A. Habit and habitat; b. Flowering plant; c. Inflorescence; d. Two axillary inflorescences; e. Leaf indumentum–adaxial; f. Leaf indumentum–abaxial; G. Stem,peduncle and pedicel indumentum; h. Single flowering axillary inflorescence; i. Flowering inflorescence (photos by M. Taram).

FiG. 2. Whytockia arunachalensis Taram, D.Borah & Tag: a. Flower–side view, showing indumentum on the corolla outside; b. Flower–top view; c. Flower–front view,showing pink glandular hairs on the corolla floor and glandular hairs around the corolla opening; d. Cut open corolla–top view, showing pink glandular hairs on the corolla floor; e. Cut open corolla–side view, showing stamens with twisted filaments; f. Cut open corolla–front view, showing two rows of pink glandular hairs on the corolla floor and stamens with twisted filaments;G. Cut open corolla–back view,showing two rows of smaller glandular hairs on the corolla floor to the left and right of the rows of pink glandular hairs and stamens with twisted filaments; h. Pistil; i. Calyx and pistil with orange disc; j. Ovary–transverse cross-section, showing two locules and bifid intrusive placentae (photos by M.Taram).

FiG. 3. Congeners of Whytockia arunachalensis Taram, D.Borah& Tag:W. sasakii(Hayata) B.L.Burtt: A. Habit; b. Vegetative shoot; c. Leaf with chalk excretions; d. Stem section with node; e. Inflorescence. W. tsiangiana (Hand.-Mazz.) A.Weber: f. Plant in natural habitat; G. Vegetative shoot; h. Inflorescence (photos by M. Möller).

FiG. 4. Congeners of Whytockia arunachalensis Taram, D.Borah & Tag:W. sasakii (Hayata) B.L.Burtt: A. Flowers–oblique front view, showing glabrous outside of corolla and two lines of long yellow glandular hairs on the corolla floor; b. Flower– front view, showing two lines of long yellow glandular hairs on the corolla floor (blue arrows), and additional long glandular hairs in lateral positions (red arrows); c. Clavate hairs on flower tube floor; d. Calyx and pistil of young flower–some sepals removed to show ovary,style and stigma;e. Calyx and pistil of mature flower–some sepals removed to show ovary,style and stigma;f. Calyx indumentum (Wen-Pen Leu 1592 [E]; W.tsiangiana (Hand.-Mazz.) A.Weber: G. Flower-oblique lateral view; h. Corolla- oblique front view,showing two lines of very long yellow glandular hairs on the corolla floor ending in a prominently long cluster of hairs (blue arrows), and additional very long yellow glandular hairs in lateral positions (red arrows); i. Calyx indumentum (Möller M. & Wei Y.G. MMO 06-811 [E]; (photos by M. Möller).