Perilimnastes uniflora J.H.Dai, T.V.Do & Ying Liu, 2023

Dai, Jin-Hong, Van Do, Truong & Liu, Ying, 2023, Four new species of Perilimnastes (Sonerileae, Melastomataceae) from Vietnam, PhytoKeys 235, pp. 1-19 : 1

Perilimnastes uniflora J.H.Dai, T.V.Do & Ying Liu sp. nov.

Figs 7 , 8

Type.

Vietnam. Đà Nẵng: Hoa Ninh , Ba Na Hills, 1,360 m elevation, in forests on damp rocks along steam, 22 Nov 2019, Jin-hong Dai and Ying Liu 814 (holotype: PE; isotypes: A, SYS, VNMN) .

Diagnosis.

Resembles P. guillauminii and P. rupicola in having raphide crystals, 3-veined leaves with cuneate base and somewhat acuminate apex, and narrow calyx lobes, but differs from P. rupicola in its pink anthers (vs. yellow) and from both in the stems glabrous except for minute brown glands when young (vs. covered with long bristles in P. guillauminii and hyaline uniseriate hairs in P. rupicola ) and pedicel 4 mm long at fruiting stage (vs. 16 mm long in P. guillauminii and 22 mm long in P. rupicola ).

Description.

Shrublets or somewhat woody herbs, to 30 cm tall, with raphides in all parts. Stems prostrate at middle and lower parts, branched, with adventitious roots at lower nodes; branchlets quadrangular and with sparse minute brown glands when young, glabrescent; older branches obtusely 4-sided; leafy distally and leafless proximally. Leaves opposite, equal to unequal in a pair, with minute brown glands only when young, glabrescent when mature; petiole 0.5-2 cm long; leaf blade obovate to obovate-lanceolate, sometimes elliptic, 4.2-9.5 × 1.3-3.4 cm, papery, 3-veined with the lateral two veins diverged from the midvein at or above the base, green to dark green adaxially, pale green abaxially, base cuneate to narrowly cuneate, margin entire or inconspicuous minutely repand, apex acuminate to long acuminate, sometimes caudate. Inflorescences terminal, flower solitary, subtended by a pair of bracts ca. 4 mm long. Flowers 4-merous; pedicel ca. 2 mm long, 4 mm at fruiting stage, glabrous; hypanthium funnel-shaped, 5-6 mm long, glabrous except for minute glands; calyx lobes 4, linear, 6-9 mm long, with minute glands; petals pinkish-purple, 11-13 × 4-6 mm, ovate, minutely oblique, apex acute to short acuminate, glabrous on both sides; stamens 8, isomorphic, filaments pink, ca. 6 mm long, glabrous, anthers lanceolate, pink, 5-7 mm long, connective decurrent, forming two ventral lobes and a dorsal spur; ovary half as long as hypanthium (crown excluded), ovary crown wedge-like, 4-lobed; style 13-15 mm long. Capsule cup-shaped, ca. 5 × 5 mm, 4-sided; hypanthium 8-ribbed; crown enlarged enclosing an obpyramidal space; placental column unbeaked, 4-horned; placenta thready.

Phenology.

Flowers in June and produces old fruits in November.

Etymology.

The specific epithet is based on the solitary flowers of this species.

Distribution.

Perilimnastes uniflora is currently only known from Ba Na Hills, Hòa Ninh, Đà Nẵng, Vietnam (Fig. 1 ). It occurs on damp rocks along streams in forests, at 1,360 m elevation.

Figures

Figure 1. Distribution of Perilimnastes multisepala (triangle), P. setipetiola (square), and P. uniflora and P. banaensis (solid circle).

Figure 7. Holotype of Perilimnastes uniflora, Jin-hong Dai and Ying Liu 814 (PE). The inset shows raphides (as white oblong spots) on adaxial leaf surface under stereoscope. Scale bars: 5 cm, 1 mm (inset).

Figure 8. Perilimnastes uniflora A habit B a flowering individual C close-up of a branchlet D adaxial (left) and abaxial (right) leaf surfaces E a flowering branch F close-up of an inflorescence showing a solitary flower G top view of a flower H longitudinal section of a flower showing the isomorphic stamens I longitudinal section of an old capsule showing enlarged ovary crown and morphology of the placental column and placentas. Scale bars: 5 mm (D, G, H); 2 mm (I). All from Jin-hong Dai and Ying Liu 814 (A, PE, SYS).