Research Article |
Corresponding author: Phetlasy Souladeth ( p.souladeth@nuol.edu.la ) Academic editor: Alan Paton
© 2017 Phetlasy Souladeth, Shuichiro Tagane, Meng Zhang, Norikazu Okabe, Tetsukazu Yahara.
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:
Souladeth P, Tagane S, Zhang M, Okabe N, Yahara T (2017) Flora of Nam Kading National Protected Area I: a new species of yellow-flowered Strobilanthes (Acanthaceae), S. namkadingensis. PhytoKeys 81: 11-17. https://doi.org/10.3897/phytokeys.81.13203
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A new species of Acanthaceae, Strobilanthes namkadingensis Soulad. & Tagane from Nam Kading National Protected Area, Bolikhamxay Province, central Laos, is described and illustrated. It is characterized by long spicate inflorescences consisting of 6-32 flowers, yellow corolla, the absence of long white hairs on the bracts and 4–6 seeds per capsule. Three DNA barcode regions of the partial genes for the large sub-unit ribulose-1,5-bisphosphate carboxylase oxygenase (rbcL) and maturase K (matK) and internal transcribed spacers (ITS) are also provided.
DNA barcoding, Indochina, Laos, Sericocalyx , taxonomy
Strobilanthes Blume, consisting of ca. 400 species is one of the largest genera in the family Acanthaceae (
Here, we describe a new species of Strobilanthes from Nam Kading National Protected Area, Bolikhamxay Province, central Laos. The national park covers an area of 169 ha, with an elevation gradient from 138 m in the lowland to 1,514 m at the summit of Phou Pa Paek and is bisected by the Nam Kading River. The climate is most strongly influenced by the south-west monsoon from April to October that brings 90 percent of the annual precipitation. Temperature in the lowland of Bolikhamxay Province varies between 20°C and 30°C, but in the high altitude areas of Nam Kading Protected Area it may drop to as low as 5°C during dry season from December to February (
During a botanical survey in Nam Kading National Protected Area in December 2016, a wild, yellow-flowered species of Strobilanthes was collected in the semi-shaded understory of semi-evergreen forest. To determine its identity, we made a morphological comparison to closely related species based on dried specimens at herbarium (BKF, FOF, FU, RUPP and SAR), digital images of specimens on the webpages of JSTOR Global Plants [https://plants.jstor.org/ (accessed 22 Feb. 2017)], K [http://apps.kew.org/herbcat/navigator.do (accessed 22 Feb. 2017)] and P [https://science.mnhn.fr/institution/mnhn/collection/p/item/search (accessed 22 Feb. 2017)], and the relevant literature of surrounding countries including Cambodia, China, Japan, Laos, Thailand and Vietnam (e.g.
The purpose of this paper is to describe and illustrate this as a new species, Strobilanthes namkadingensis Soulad. & Tagane accompanying with DNA barcodes of the three DNA barcode regions, the partial genes for the large subunit ribulose-1,5-bisphosphate carboxylase oxygenase (rbcL) and maturase K (matK) (CBOL Plant Working Group 2009) and the internal transcribed spacer region of the nuclear ribosomal DNA (ITS). DNA sequencing for rbcL and matK followed to the published protocols (Kress et al. 2009, Dunning and Savolainen 2010) and for ITS according to
Strobilanthes namkadingensis is distinguished from all the previously known species of Laos and its surrounding countries including China, Cambodia, Thailand and Vietnam clearly by a combination of 6–32 flowered spikes up to 10.5 cm long, yellow corolla, the absence of long white hairs on the bracts and 4–6-seeded capsule. In the region, S. namkadingensis is similar to Strobilanthes squalens S.Moore of Vietnam and Sericocalyx thailandicus Bremek. of Thailand in having yellow corolla and long-beaked floral bracts, but distinguished by its long spikes (vs. less than 3 cm long), broader floral bracts (obovate-elliptic to broadly elliptic vs. lanceolate to ovate-lanceolate), smaller corolla (1.9–2.1 cm long vs. less than 1.7 cm long), and the absence of long white hairs on the bracts.
Strobilanthes namkadingensis Soulad. & Tagane. A flowering branch B abaxial leaf surface C inflorescence D flower E side view of corolla F floral bracts G corolla opened out H fruit with calyx J longitudinal section of capsule showing seeds (from Tagane et al. L426, FU). All scale bars: 5 mm.
LAOS. Bolikhamxay Province, Nam Kading National Protected Area, in semi-evergreen forest, beside a dried rocky stream, 18°12'17.9"N, 104°33'34.5"E, alt. 146 m, 26 Dec. 2016, with flowers and fruits, Tagane S., Yahara T., Zhang M., Okabe N., Souladeth P., Sengthong A., Chayer S. L426 (holotype-HNL!, isotypes-FOF!, FU!, K, KYO!, P).
Anisophyllous shrub, 1.5 m tall. Stem terete, densely covered with white hairs, pale yellow green when dried. Leaves slightly unequal in each pair, petiolate; blade broadly elliptic, ovate-elliptic, (0.7–)5.5–11 × (0.2–)2.2–4.5 cm, apex acuminate, base cuneate, briefly decurrent onto petiole, margin shallowly crenate, chartaceous, pale yellow green adaxially, light pale yellow green abaxially, sparsely strigose and scabrous on both sides, densely covered with cystoliths adaxially; midrib prominent on both surfaces, secondary veins 6–8 pairs, prominent on both surfaces, tertiary veins scalariform-reticulate, faintly visible to invisible; petiole 0.5–1.3 cm long, scabrid adaxially, glabrous abaxially, margin ciliate. Inflorescences spicate, terminal and axillary, (2–)3–10.5 cm long, 6–32-flowered; outer (inflorescence) bract narrowly elliptic-ovate, 1.4–2.1 × 0.4–0.5 cm, apex acute to acuminate, sessile, shortly puberulent adaxially, sparsely with short stiff hairs at margins and on midveins on both surfaces; floral bracts obovate-elliptic to broadly elliptic, ca. 1.7 × 0.7 cm long, apex caudate, acumen up to 0.8 cm long, persistent, pale yellow green, sparsely pilose with glandular hairs adaxially, shortly puberulent, with grand-tipped hairs abaxially, margin ciliate with large-celled white hairs; bracteole 2, linear, 5–7 mm long, glandular hairy. Calyx lobes 5, linear, ca. 5–9 mm long, apex acute, slightly accrescent in fruit, upper three and lower two calyx lobes are fused ca. 2 mm from the base, covered with cystoliths adaxially, glandular hairy abaxially. Corolla yellow, funnel-shaped, 1.9–2.1 cm long, 0.8 cm in diam., membranaceous, hairy with short erect hairs outside, pilose with long white hairs inside of tube, corolla lobes 5, elliptic to suborbicular, ca. 3.8 × 3.1–3.8 mm, apex rounded. Stamens 4, didynamous; the shorter pairs of filaments ca. 1.5 mm long, with a few white hairs; the longer ones 5–6.5 mm long, pilose with long white hairs except upper 2/5, base of filaments adnate to corolla tube; anthers ca. 2–2.2 mm long, dorsifixed, attached lower 1/3 part of anther (monadelphous). Style 1.2 cm long, sparsely pilose, stigma ca. 2 mm long, glabrous. Capsule narrowly ellipsoidal, 8.4–10 mm long, ca. 2.8 mm in diam., glandular hairy, 4–6-seeded. Seeds spirally arranged on free-central placenta, suborbicular, 2 mm height, 1.8 mm width, 0.2 mm thick, strongly flattened, light yellow brown, glabrous.
Laos, Bolikhamxay Province (so far known only from Nam Kading National Protected Area).
Strobilanthes namkadingensis is found in semi-shaded understory of semi-evergreen forest beside a dried stream; at alt. 146 m. The flowering and fruiting specimen was collected in December.
Tagane et al. L426: LC257983 (rbcL), LC257984 (matK) and LC257953 (ITS).
This specific epithet namkadingensis refers to the type locality.
Data Deficient (DD) (
The authors are grateful to the managers and staff of Nam Kading National Protected Area for supporting our botanical inventory in the protected area. We thank curators of the herbaria BKF, FOF, FU, RUPP and SAR for their specimens accessible, and Mariko Akama (Kyushu University) and Keiko Mase for their help in DNA sequencing. The editors of the journal and two anonymous reviewers are also sincerely thanked for their useful and constructive comments. This study was supported by the Environment Research and Technology Development Fund (4-1601) of the Ministry of the Environment, Japan, JSPS KAKENHI (15H02640).