Andrographis megamalayana Gnanasek., Karupp. & G.V.S. Murthy, 2016

Gnanasekaran, Gunadayalan, Karuppusamy, Subbiah & Murthy, Garimella Venkata Suryanarayana, 2016, Andrographis megamalayana (Andrographinae: Acanthaceae), a new species from the southern Western Ghats, India, Phytotaxa 244 (1), pp. 89-95 : 89-94

Andrographis megamalayana Gnanasek., Karupp. & G.V.S. Murthy , sp. nov. Figs. 1–4

Diagnosis: Andrographis megamalayana resembles A. neesiana Wight , but can be easily distinguished from the latter by its small herbaceous habit, smaller leaves that are narrowly elliptic at base to lanceolate or oblong towards apex, with 3–6 pairs of veins, sessile or presence of very short petiole, longer and linear calyx lobes often exceeding the ventricose portion of corolla tube, and subglobose to obovoid seeds.

Type:— INDIA. Tamil Nadu: Theni District, Megamalai Wildlife Sanctuary, Maharajamettu , 9°35’ 56” N ; 77°17’18”, at 1560 m, 07 July 2012, G. Gnanasekaran 126849 (holotype: CAL!; isotypes, MH!) .

Herb, up to 60 cm high. Stems 4-angled, swollen at nodes, glandular-pubescent throughout, rarely glabrous. Leaves sessile or shortly petiolate; leaf blades variable in shape, lower ones narrowly elliptic or ovate, upper ones lanceolate or oblong, 2–6.5 × 0.5–2.5 cm, base obtuse, subcordate or rarely cuneate, margins entire or rarely revolute, apex acute or abruptly acuminate, strigose towards margins above when young ( Fig. 1 : B); midrib conspicuous beneath ( Fig. 1 : C); lateral veins 3–6 pairs; hypostomatous ( Fig. 2 : I); petioles 0–2 mm long, puberulous to glabrous. Inflorescences racemose, axillary and terminal, branched, up to 5.5 cm long, crowded towards apex, forming a terminal subcapitate head ( Fig. 1 : A, 2: A, B); rachis 4-angled, densely glandular-pubescent; flowers closely arranged (interstices 0.2–0.8 cm long), twisted at right angles to each other, one-sided; peduncles 1–2.5 cm long, glandular-pubescent. Bracts narrowly ovate to oblong, 2–3.2 × 0.6–0.8 mm, hairy on the margins, apex acute, glandular-pubescent adaxially, antrorsely strigulose abaxially, green. Bracteoles 2, linear, 1.8–2 × 0.3–0.4 mm, hairy on the margin, acuminate at apex, glandular-pubescent outside, antrorsely strigulose inside, green. Calyx 5-lobed; lobes subequal, linear, 4.5–6.5 × 0.6– 0.8 mm, hairy on the margin, acuminate at apex, glandular-hirsute outside, antrorsely strigulose inside, almost equal or longer than the ventricose portion of corolla tube ( Fig. 1 : D). Corolla 2-lipped, 1.5–1.7 × 1.2–1.4 cm, white, purpletinged; tube prominently ventricose, 6–7.7 × 1.7–3 mm, glandular-hirsute above ( Fig. 2 : E), glabrous below; upper lip spathulate-oblong, entire at margins, minutely 2-lobed at apex (0.6–0.8 mm long), 8.5–9 × 2.8–3 mm, glabrous inside, glandular-hirsute outside, 6-veined; lower lip 3-lobed, entire at margins, acute or obtuse at apex, 7–7.5 × 5.5–6.2 mm, glabrous inside except at centre of middle lobe, glandular-hirsute outside, purple-striped; middle lobe ovate, 2.4–2.8 × 2.6–3 mm, hirsute at centre, 3-veined; lateral lobes oblong, 2.2–3 × 1.3–1.6 mm, 3-veined. Stamens 2, exserted, adnate to base of ventricose portion of corolla tube; filaments 9–10 mm long, distinctly dilated at base, retrorsely pilose throughout; anthers oblong, 1.8–2.3 × 0.6–0.8 mm, pilose at base, deep purple. Pollen grains ( Fig. 3 : A – C) 3-colporate, subprolate, 34–37 × 29–33 μm; ectoaperture, c. 30.8 × 11.6 μm, tapering gradually towards the poles; endoaperture, c. 4.4 × 5.8 μm, elliptical; exine thickness c. 2.41 μm; tectum ornamentation distinctly bireticulate. Ovary oblongoid, 1.8–2 × 0.8–1 mm, glandular-hairy; ovules 6 in each cell; style 1.4–1.6 cm long, antrorsely bristled-hairy, pinkish; stigma linear, green. Capsules ( Fig. 1 : G) linear-oblong, 18–22 × 3–4.5 mm, acute, compressed at right angles to septum with a median longitudinal groove, densely glandular inside and outside, brown. Seeds ( Fig. 3 : D– G) 10–12, subglobose to obovoid, 1.7–2.2 × 1.2–1.6 mm, narrowly oblique at base, obtuse at apex, very hard, scrobiculate, verrucose, yellowish brown.

Habitat:—Grasslands, at elevations between 1200 and 1600 m.

Distribution:—Endemic to India, occurs in Kerala (Idukki district) and Tamil Nadu (Dindigul and Theni districts). ( Fig. 4 ).

Flowering and fruiting:—June to December.

Etymology:— Andrographis megamalayana is named after the type locality, Megamalai Wildlife Sanctuary located in Theni district of Tamil Nadu, southern Western Ghats, India.

Conservation status:— Andrographis megamalayana is provisionally evaluated here as ‘ Vulnerable ’ [VU B1ab(iii)+2ab(iii)] using IUCN Red List Categories and Criteria version 3.1 ( IUCN 2012). This species is so far known only from very few localities and extant populations are under the threat factor of habitat fragmentation due to the cultivation of commercial crops. However, extensive explorations are needed in the adjacent localities to know the exact extent of occurrence of this species, for an accurate evaluation of its threat status.

Inter-relationship:— Andrographis megamalayana is morphologically similar to A. neesiana by possessing subcapitate head inflorescence but differs from many characters as listed in Table 1.

Characters A. megamalayana A. neesiana

Habit Short herb, up to 60 cm high Tall undershrub, 1–3 m high

Leaves Lanceolate-oblong, 2–6.5 cm long, obtuse or subcordate Broadly elliptic, 4–14 cm long, attenuate-decurrent at at base, upper surface strigose only towards margins; pale base; upper surface densely strigose throughout; dark green when fresh and pale yellowish when dry green when fresh and dark black when dry

Lateral veins 3–6 pairs 5–9 pairs

Petioles Sessile or up to 2 mm long Distinctly petioled, 5–15 mm long

Calyx lobes Linear, almost equal or exceeding the ventricose portion Lanceolate, smaller or nearly reaching ventricose portion of corolla tube, 4.5–6.5 mm long of corolla tube, 3–4.5 mm long

Corolla Narrow and long; white with purple tinge Comparitively broad and short; purplish

Pollen grains Comparitively small (34–37 × 29–33 μm); ectoaperture Large (37–40 × 31–36 μm), Ectoaperture c. 37.26 ×

c. 30.83 × 11.69 μm; endoaperture c. 4.42 × 5.83 μm; 12.29 μm; endoaperture c. 5.29 × 5.08 μm; mesocolpium mesocolpium c. 14.39 μm; apocolpium c. 6.22 μm; exine c. 17.08 μm; apocolpium c. 9.62 μm; exine thickness c. thickness c. 2.41 μm 2.61 μm

Seeds Subglobose, obovoid, or rarely oblongoid, 1.7–2.2 mm Oblongoid-subcylindric, 1.8–3 mm long long

Additional Specimens examined (Paratypes):— INDIA. Kerala: Idukki District, Devicolam , 5500 ft (c. 1830 m), s.dat., R. H. Beddome 379 ( BM001050060 ) ; Devicolam, 1580 m, 11 September 1968, D. B. Deb 30485 ( MH) ; Mangaladevi temple, 1300 m, 09 October 1976, K. Vivekananthan 48634 ( CAL, MH) ; Suryanelli, 20 September 1987, B. Gurudev Singh & K. R. Sasidharan 12477 ( FRC) ; Near gap road, on the way to Poopara from Munnar , 12 October 2013, S. Karuppusamy & V. Ravichandran 1203 (Madura College Herbarium, MH) ; Below the gap road, between Thanrukanal and Munnar, 12 October 2013, S. Karuppusamy & V. Ravichandran 1204 ( Madura College Herbarium , MH). Tamil Nadu: Dindigul District , Pulney hills, s.dat., R. H. Beddome 377 ( BM001050058 ) ; Theni District, Way up High Wavy Mountains , 3000–4000 ft (c. 1200 m), 06 September 1925, K. C. Jacob 17528 ( MH) ; Megamalai, 1300 m, 21 July 1988, V. Lakshmanan 88929 ( MH) ; Kardana estate (Block No. 10), 1500 m, 21 November 1988, V. Lakshmanan 88002 ; Megamalai Wildlife Sanctuary, Maharajamettu, 1560 m, 24 August 2013, G. Gnanasekaran 126900 ( MH) ; Megamalai Wildlife Sanctuary, Maharajamettu, Iravangalaru, 1500 m, 13 October 2013, S. Karuppusamy & V. Ravichandran 1231, 1232 (Madura College Herbarium, MH) ; Megamalai Wildlife Sanctuary, Chettiyar kaadu mottai, 14 October 2013, S. Karuppusamy & V. Ravichandran 1267 (Madura College Herbarium, MH) .

Figures

FIGURE 1. Andrographis megamalayana. A. Habit. B. Adaxial leaf surface. C. Abaxial leaf surface. D. Flower. E. Opened corolla showing androecium. F.Pistil. G. Capsule. H. Seed. (G. Gnanasekaran 126849, MH).

FIGURE 2. Andrographis megamalayana. A. Flowering branch. B. Fruiting branch.. C. Flower. D. Lower corolla lip with stripes–closeup. E–I. Portion of SEM photographs: E. Corolla outside. F. Filament. G. Style. H. Adaxial leaf surface. I. Abaxial leaf surface. J. Holotype (G. Gnanasekaran 126849).

FIGURE 3. Andrographis megamalayana. A & B. Pollen grains. C. Ornamentation of pollen. D–G. Light and SEM photographs of seed and surface ornamentation.

FIGURE 4. Distribution map of Andrographis megamalayana (Star–Fresh and Circle–Herbarium collections).