Sonerila erectifolia Phonep., Soulad. & Tagane, 2021

Phonepaseuth, Phongphayboun, Souladeth, Phetlasy, Souvannakhoummane, Keooudone, Vongthavone, Thyraphon & Tagane, Shuichiro, 2021, Two new species of Sonerila Roxb. (Melastomataceae) from Laos, European Journal of Taxonomy 755, pp. 136-148 : 137-141

Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov.

urn:lsid:ipni.org:names:77217798-1

Figs 1–2

Diagnosis

Sonerila erectifolia sp. nov. is similar to Sonerila violifolia in its scorpioid or subumbelliform inflorescence, but it differs in the length of stem (ca 1 cm long in S. erectifolia sp. nov. vs 10–18 cm long in S. violifolia ), the venation of the leaves (2 veins running from the base of lamina vs pinnately veined with 2–3 lateral primary veins), hairiness of leaves (sparsely covered with whitish hairs on veins abaxially vs glabrous), the length of the petiole (6–10 cm long vs 1–7 cm long), and number of flowers per inflorescence (5–12(–18) flowers vs 1–9 flowers). For further comparison see Table 1 .

Material examined

Type LAOS • Champasak Province, Dong Hua Sao National Protected Area, near Nong Luang Village, on rocks in open grassland at the summit of the Bolaven Plateau ; at 1230–1270 m a.s.l.; 17 Sep. 2020; Souladeth, Souvannakhoummane, Phonepaseuth & Vongthavone L3950 ; holotype: FOF!; isotypes: BKF, E, KAG .

Paratype LAOS • Champasak Province, Dong Hua Sao National Protected Area, near Nong Luang temple, on rocks in open grassland; 1154 m a.s.l.; 16 Sep. 2020; Souladeth, Souvannakhoummane, Phonepaseuth & Vongthavone L3823 ; E, FOF!, HNL, KAG .

Etymology

The specific epithet refers to the plant having erect leaves.

Vernacular name

ຊີດິນໃບຕັ້ງ [ʻSeedin Baitungʼ (meaning: ʻ Sonerila with erect leavesʼ)].

Description

Herbs acaulescent or with a short rhizomatous stem, 10–14(–20) cm tall including inflorescences. Rhizome cylindrical, 2–3 cm long and 5–10 mm in diam, covered with long blonde hairs, hairs 3–4 mm long. Leaves simple, forming a basal rosette, erect; lamina elliptic-oblong, ovate-elliptic, 4–6 × 2–2.5 cm, membranous, green, sparsely covered with whitish hairs on margin and tip adaxially, pale green, sparsely covered with whitish hairs on veins abaxially, apex mucronate or rounded, base cuneate or attenuate (to truncate), margin finely crenate and sparsely long ciliate, with 2 pairs of primary lateral veins arising from base of lamina; petiole 6–10 cm long, light green to reddish-brown, sparsely covered with long pale green hairs. Inflorescence terminal, scorpioid cyme or subumbelliform cymes, 5–12(–18)-flowered; peduncle 10–15 cm long, 2–2.5 mm in diam., glabrous to sparsely hairy. Bracts minute. Hypanthium cylindrical, 8–9 mm long, 2 mm in diam., reddish brown, glabrous, Calyx lobes 3 (or rarely 4), triangular, ca 1 × 2.5 mm, apex short acuminate; pedicel 6–12 mm long, 0.9–1 mm in diam., glabrous. Petals 3 (or rarely 4), elliptic-oblong, 9–11 × 5–6 mm, pinkish purple to light pink, rarely white adaxially, pearl pink abaxially tinged with dark pink along midvein. Stamens 3 (or rarely 4), anthers lanceolate, 7–8 mm long, curved, basally inflated and deeply cordate, bright yellow; filaments 6–8 mm long, glabrous, usually pale pink. Ovary 3-locular (or rarely 4), ellipsoid, style 11–13 mm long, glabrous, pale pink, sometimes pale green to white, stigma capitate, glabrous, white. Fruits and Seeds not seen.

Distribution, habitat and phenology

Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov. grows on exposed, open, moss-covered bedrock on the Bolaven Plateau, where it is found together with Boesenbergia burttii (K.Larsen & Jenjitt.) Mood & L.M.Prince ( Zingiberaceae Martinov ) and several fern species including Oleandra undulata (Willd.) Ching ( Oleandraceae Ching ex Pic.Serm. ), Nephrolepis cordifolia (L.) K.Presl ( Nephrolepidaceae Pic. Serm. ), and Leucostegia truncata (D.Don) Fraser-Jenk ( Hypodematiaceae Ching ), at 1230–1270 m a.s.l. Flowering in September.

Preliminary conservation status

Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov. is found only at the top of the Bolaven Plateau (near Nong Luang Village). The number of mature individuals is estimated to be fewer than 250, which together generate an area of occupancy of less than 10 km 2. The area is a well-known tourist attraction with associated habitat disturbance that could affect the survival of this species. Therefore, we assess the species as Critically Endangered (CR) B2ab(iii) ( IUCN 2019).

Figures

Fig. 1. Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov. A. Habit. B. Front view of flower. C. Flower bud. D. Hypanthium and style. E. Stamens. Line drawings from holotype (Souladeth et al. L3950) by K. Souvannakhoummane.

Fig. 2. Sonerila erectifolia Phonep., Soulad. & Tagane sp. nov. A. Habitat (on open moss-covered bedrock). B. Close-up of plant (left: pink flowers, common; right: white flowers, rare). C. Habit. D. Inflorescence (left: pink flowers; right: white flowers). E. Young fruits. F. Top view of young fruit. G. Cross sections of young fruit. H. Rhizome. I. Upper surface of lamina. J. Lower surface of lamina. Photos by P. Phonepaseuth on 17 September 2020.