Gymnostachyum kanthanense Kiew, 2014

Pei Chih, Tan Joanne, R., KIEW, L. G., SAW & A. R., UMMUL-NAZRAH, 2014, Three New Species from Gunung Kanthan, a Limestone Tower Karst in Perak, Malaysia, Phytotaxa 177 (3), pp. 146-154 : 147-148

1. Gymnostachyum kanthanense Kiew , sp. nov., Fig. 2

Type: — MALAYSIA. Perak: Kuala Kangsar District, Chemor, Gunung Kanthan , 04°46’06.9”N, 101°07’26.1”E, 179 m, 22 May 2013, Tan J. P. C ., Kiew R . & Kueh H. L. FRI 78060 (holotype KEP! (flower), isotypes K!, KEP! (fruit), SING!) .

Gymnostachyum (Acanthaceae) , characterized by a combination of its two stamens and many seeds ( Hansen 1985), is represented in Peninsular Malaysia by 13 species ( Ridley 1923) two of which, Gymnostachyum decurrens Stapf with two varieties and Gymnostachyum diversifolium C.B.Clarke , occur on limestone. Both are low creeping plants compared with the non-limestone species that are erect and rather robust. G. diversifolium is distinct in its longer leaves (7–13 × 3.5–4 cm), longer inflorescences (11–24 cm long), and larger flowers (ca. 2.5 cm). The new species is more similar to G. decurrens in its shorter inflorescence (ca. 8 cm long) and smaller flowers (1–1.5 cm long) but is distinguished from it by leaf and inflorescence characters.

Creeping herb with soft white hairs on stem, petiole and upper and lower leaf surfaces. Stems weak, becoming decumbent, apex erect flowering at ca. 4 cm tall. Leaves cauline, opposite, ca. 1 cm apart; petiole terete, to 3 cm long on lower leaves; lamina membranous, pale green above with grey-green blotches along lateral veins, white-green beneath, broadly lanceolate, 5–7 × 3.5–4.5 cm, base abruptly rounded or truncate, decurrent for 2–8 mm, margin scarcely shallowly crenate, apex acute-rounded; midrib and veins impressed above; lateral veins ca. 7 pairs. Inflorescences erect, terminal spikes, deep purple-green, minutely hairy, ca. 5–6 flowers on one side of the rachis, 3 spikes together at apex, the long spike to 4.5 cm long, the second smaller and the third scarcely developed, peduncle ca. 2 cm long; bracts minute, acute, 1–1.5 mm long; pedicels 0.5–1 mm long. Calyx 5, divided to base, lobes equal, narrowly linear, 4–5 × 0.75 mm long, purplish green, sparsely hairy outside, clasping the corolla tube. Corolla white tinged purple outside, inside white with scattered minute purple spots except for the deep purple lower lip, sparsely hairy outside with stalked glandular hairs, ca. 18 mm long, narrowly cylindric at base, 7–9 × 1.5–2 mm, expanding distally to funnel-shaped throat 6–7 × 4–5 mm, upper lip erect, 5–6 mm long, apex emarginate (shortly bilobed), flat (not cucullate), lower lip 4–4.5 mm long, strongly reflexed, deep purple with two glistening ragged white bands. Stamens 2, filaments white, 8–9 mm long, inserted at the base of the throat, anthers deep purple, exserted beyond the throat, positioned below the apex of upper lip, narrowly ellipsoid, 1.75–2 mm long, thecae 2, equal. with two minute mucronate appendages at base, densely covered in very short glandular hairs with a thick band of white hairs along the longitudinal line of dehiscence, pollen white; staminodes absent. Nectary annular, dirty cream-coloured, 0.5–1 mm high, upper margin undulate. Ovary green, cylindric, 2–2.5 × 1 mm long, glandular hairs dense to sparse, ovules many per locule; style white, 13–18 mm long, densely to sparsely hairy, stigma hooked, 0.75–1 mm long, positioned between the anthers. Fruit subsessile, narrowly cylindric, ca. 12 × 1 mm, retinacula ca. 10 per locule, calyx patent and star-like and persisting after the fruit has fallen. Seeds up to 20, laterally compressed, ca. 1.5 × 0.75 mm, surface minutely pitted.

Distribution and habitat:― Known only from the type specimen, which was growing on what the Lafarge’s Kanthan Quarry Plant, had called ‘Area C’. It is apparently a rare species as only one clump was found during the survey. On limestone tower karst, growing in light shade on limestone-derived soil just below the crest of the ridge where it formed a clump about 3 m across.

Comparison:― Similar to Gymnostachyum decurrens in its creeping habit, spicate inflorescences, and white flowers 1–1.5 cm long with a purple lip but it is different in its leaves that are scarcely decurrent (not broadly winged to the base of the petiole as in G. decurrens ), lamina that is less than twice as long as broad (not twice or more longer than wide) and in its shorter inflorescence (to 4.5 cm long not 8–17 cm long as in G. decurrens ).

Conservation status:― Critically Endangered CR B2 ab (iii, iv), D1. Currently known only from one clump from the type locality .

Figures

FIGURE 2. Gymnostachyum kanthanensis. A. Habitat on steep earth-covered slope up to the top of the cliff. B. Flowering plants. C. Front view of the flower. D. Side view of the spike and flowers. E. Split open fruit and seeds. Photo by P.T. Ong.