Research Article |
Corresponding author: Abdul Rahman Rafidah ( rafidahar@frim.gov.my ) Academic editor: Bo Li
© 2024 Abdul Rahman Rafidah, Abdul Rahman Ummul Nazrah, Poh Teck Ong.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Rafidah AR, Ummul Nazrah AR, Ong PT (2024) Gymnostachyum calcicola (Acanthaceae), a new species from limestone karst of Peninsular Malaysia. PhytoKeys 242: 273-280. https://doi.org/10.3897/phytokeys.242.122869
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A new species, Gymnostachyum calcicola Rafidah, sp. nov. (Acanthaceae) is described from limestone karst in Peninsular Malaysia. Characters distinguishing it from related species, colour photographs, botanical illustration and provisional conservation status are provided.
Andrographideae, endemic, flora, Kelantan, taxonomy
Gymnostachyum Nees (Acanthaceae) is a genus consisting of about 30–50 species distributed mainly in tropical Asia (
The discovery of this distinctive new species is part of the comprehensive survey of the Peninsular Malaysia limestone flora in 2017. The species was found on the limestone hills in Federal Land and Development Authority (FELDA) Chiku and Perasu in Kelantan, and is endemic in Kelantan. The species inhabits partially shaded areas, and roots in cracks with thin soil layer on rocks at the base to the summit of karst limestone. After carefully examining the herbarium specimens and living material and reviewing the relevant literature, here we concluded that the newly discovered plants represented an undescribed species. Herewith, the new species is described and illustrated in detail.
Measurements and morphological character assessments of the new species were undertaken and described using specimens collected from their natural habitat and living materials grown in the
Forest Research Institute Malaysia (
Unique among Peninsular Malaysian species of Gymnostachyum by having a racemose inflorescences occasionally lower axils with pairs of flowers and dichasium inflorescence with opposite branches. Gymnostachyum calcicola shows affinity with Gymnostachyum decurrens var. decurrens and var. robinsonii by its crowded rosette leaves at the base, however it is different in the inflorescences type.
Rosette herbs. Leaves opposite; petiole pale green, to 7 cm long, not winged; lamina membranous to subcoriaceous, dark green above, sometimes with grey blotches, white-green beneath, narrowly oblong to elliptic, ca. 11 × 4–5 cm, base abruptly truncate, decurrent for 2 cm, margin entire, slightly wavy, apex unequal, slightly acute to blunt; midrib and veins slightly sunken above, glabrous beneath; lateral veins ca. 9–10 pairs. Inflorescences green, erect, terminal, racemose occasionally lower axils with pairs of flowers, dichasium with opposite branches, rachis up to 30 cm long or more, minutely hairy, branches ca. 14 cm long with up to 5 flowers; bracts green, ca. 1 mm long; pedicels very short, ca. 0.5 mm long; bracteoles minute, 0.5 mm long. Flowers suberect. Calyx divided near the base, lobes 5, equal, narrowly linear, 2–3 × 0.5–1 mm long, green, hairy outside, clasping the corolla tube. Corolla white outside, inside white with scattered minute purple spots except for the deep purple lower lip, deep purple at the median lobe, minutely glandular hairy outside, ca. 12–14 mm long, narrowly cylindric at base, tube 10 × 1 mm, expanding distally to funnel-shaped throat, upper lip erect, ca. 3 mm long, apex slightly bilobed, flat, lower lip unequal, the middle lobe much shorter. Stamens 2, filaments white, 6–7 mm long, inserted at the base of the throat, glabrous, anthers purple-white, inserted, positioned below the apex of upper lip, narrowly oblong, ca. 2 mm long, thecae 2, equal, both with minute mucronate appendages at base, densely covered with short stalked glandular hairs with dense white hairs along longitudinal line of dehiscence; staminodes absent. Nectary annular, cream-coloured, ca. 1 mm high, upper margin entire. Ovary green, cylindric, 1–1.5 mm long, densely covered in short glandular hairs, ovules many per locule; style white, up to 8 mm long, sparsely hairy, stigma hooked, less than 1 mm long, positioned between the anthers. Capsule narrowly cylindric, 10–12 × 1–2 mm, retinacula 6–7 per locule, calyx persisting after the fruit has fallen. Seeds up to 12 (probably more), obliquely ovoid, strongly compressed, ca. 1 mm longitudinal, surface minutely pitted, hairy.
Endemic to Kelantan, Peninsular Malaysia; known only from limestone hills. Species grows in small populations, always observed in shaded areas, rooting in cracks on thin soil on limestone rocks, almost to the summit of the hill.
Gymnostachyum calcicola Rafidah A flowering plant B portion of inflorescence with flowers C flower D flower with opened corolla E bract, calyx and carpel with corolla and stamens removed F indumentum of anther along longitudinal line of dehiscence G anthers (dorsal and ventral views) H seeds I fruit J-K attachment of seeds (all drawn by Mohd Aidil Nordin).
The specific epithet refers to the limestone habitat of this species.
Endangered B2 ab(i,ii,iii). Most Chiku limestone hills were visited, but only two to three hills were home to this new species. A part of Chiku limestone hills is scheduled for quarries. The survival of the species remains uncertain. The species also has been recorded in Perasu limestone hills, about 40 km away from Chiku hills. Parts of FELDA Perasu limestone have been quarried, and surrounding areas are currently disturbed by the road constructions. All hills lie outside the network of Protected Areas.
Peninsular Malaysia, Kelantan: FELDA Chiku, 11 October 2017, Aliaa-Athirah et al. 90712 (KEP), 10 October 2017, Wan Syafiq et al. FRI 90123 (KEP); FELDA Perasu, 24 April 2019, Rafidah FRI 93064 (KEP).
Characters / Species | G. calcicola | G. decurrens var. decurrens | G. decurrens var. robinsonii | G. diversifolium | G. ceylanicum* | G. kanthanense | G. pallens |
---|---|---|---|---|---|---|---|
Petiole | not winged | broadly-winged | winged | winged | winged | not winged | winged |
Lamina | |||||||
Base | abruptly truncate | broad | abruptly truncate | broad | unknown | abruptly rounded or truncate | abruptly truncate |
decurrent for 2 cm | undulate margin, decurrent | decurrent | decurrent | undulate margin, decurrent | decurrent for 2–8 mm | shortly decurrent | |
Indumentum surface (both) | Glabrous | pubescent | scabrid | pubescent | pubescent | pubescent | densely punctate |
Inflorescence | |||||||
Type | racemose | spikes | racemes | spikes | spikes | spikes | spike |
dichasium inflorescence with opposite branches | several | branched | 1 to 3 | several | 3 | slightly branched | |
Flower | occasionally lower axils with pairs of flowers | single | single | single | single opposite or in long spikes in short cymes | on one side of the rachis | single |
Calyx | |||||||
Colour | green | purple | green | pale green | dark green | purplish green | green |
Corolla | |||||||
colour | white | white | unknown | pale blue | pinkish / pale purple | white tinged purple | white |
length (mm) | 12–14 | 12–15 | 10 | 25 | 12 | 18 | 12 |
lower lip (median) | deep purple | violet | unknown | purplish (all) | yellow | deep purple | white |
indumentum | minutely glandular hairy | glandular pubescent | glandular pubescent | glandular and e-glandular hairs | unknown | stalked glandular hairs | unknown |
Capsule | |||||||
length (mm) | 10–12 | 18 | 12 | unknown | unknown | 12 | > 12 |
We would like to thank the staff of the Flora Biodiversity Programme,
The authors have declared that no competing interests exist.
No ethical statement was reported.
This research is financially supported by National Conservation Trust Fund (NCTF) Grant, under the Project “Towards conservation strategy/policy for limestone hills in Peninsular Malaysia: Understanding and documenting plant biodiversity with focus on Kelantan and Perlis limestone hills (Phase 2)” and under the Twelfth Malaysia Plan 2021-2025.
All authors have contributed equally.
Abdul Rahman Rafidah https://orcid.org/0000-0003-1055-4894
Abdul Rahman Ummul Nazrah https://orcid.org/0009-0002-7284-2592
All of the data that support the findings of this study are available in the main text.