[Botany • 2017] Strobilanthes namkadingensis • A New Species of Yellow-flowered Strobilanthes (Acanthaceae) from central Laos [Flora of Nam Kading National Protected Area I]

Strobilanthes namkadingensis Soulad. & Tagane 

 DOI: 10.3897/phytokeys.81.13203 

Abstract

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.

Keywords: DNA barcoding, Indochina, Laos, Sericocalyx, taxonomy

Figure 2. 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.  DOI: 10.3897/phytokeys.81.13203

Strobilanthes namkadingensis Soulad. & Tagane, sp. nov.

Diagnosis: 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.

Distribution: Laos, Bolikhamxay Province (so far known only from Nam Kading National Protected Area).

Habitat and ecology: 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.

Etymology: This specific epithet namkadingensis refers to the type locality.

 Phetlasy Souladeth, Shuichiro Tagane, Meng Zhang, Norikazu Okabe and Tetsukazu Yahara. 2017. Flora of Nam Kading National Protected Area I: A New Species of Yellow-flowered Strobilanthes (Acanthaceae), S. namkadingensis.
 PhytoKeys. 81; 11-17.  DOI: 10.3897/phytokeys.81.13203