Tigridiopalma exalata S.Jin Zeng, Y.C.Xu & D.F.Cui, 2021

Zeng, Si-Jin, Xu, Ye-Chun, Wang, Gang-Tao, Jia, Peng & Cui, Da-Fang, 2021, Tigridiopalma exalata, a new and endangered species of Melastomataceae from China, PhytoKeys 176, pp. 33-42 : 33

Tigridiopalma exalata S.Jin Zeng, Y.C.Xu & D.F.Cui sp. nov. Figs 3 , 4

Type.

China. Guangdong: Huizhou, Longmen , on damp slopes of ravines in broad-leaved forests, 115 m, 13 October 2019, S.Jin Zeng 982 (holotype: IBSC!; isotypes: CANT!, KUN!, PE!) .

Diagnosis.

The new species Tigridiopalma exalata resembles T. magnifica in having a short stem, huge basal leaves, scorpioid cymes, and 5-merous flowers, but differs in its ribbed and densely pale yellow puberulent petioles, connectives of longer stamens with a distinct dorsal short spur at their base, and wingless capsules.

Description.

Perennial herbs, succulent, with raphides in both vegetative and reproductive parts. Stems stoloniferous, 3-5 cm long, internodes indistinct. Leaves in a basal or sub-basal rosette, decussate; petiole somewhat square in cross-section, 6-21 cm long, abaxially ribbed, densely pale yellow puberulent; leaf blade cordate, 16-30(-58) × 16-34(-54) cm, slightly fleshy, base cordate, apex subrounded, margin ciliate and irregular abruptly denticulate, adaxial surface green, glabrous, abaxial surface usually purple, densely pale yellow puberulent on veins; secondary veins 3-4 on each side of the midvein, conspicuous; tertiary veins numerous, parallel, and connecting with secondary veins. Inflorescences terminal, scorpioid cymes, 12-50 flowers; peduncle nearly rounded in cross-section,13-27 cm long, densely pale yellow puberulent; bracts linear, ca. 0.1 cm, puberulent, caducous. Pedicel nearly rounded in cross-section, 1.2-2.0 cm long, puberulent. Hypanthium funnelform to cup-shaped, 5-sided, wingless, ca. 0.6 × 0.6 cm, puberulent, apex truncate. Calyx lobes triangular-semiorbicular, less than 0.1 cm, puberulent, apex apiculate. Petals purple, broadly obovate, ca. 1.0-1.5 × 0.7-1.0 cm, oblique, almost rhomboid, apex white, truncate and oblique. Stamens 10, 5 long antisepalous and 5 short antipetalous, arranged in 2 whorls. Antisepalous (longer) stamens 1.7-2.2 cm long; anthers 0.7-1.0 cm long; connective decurrent, basally with 2 ventral tubercles and a dorsal short spur. Antipetalous (shorter) stamens 1.2-1.5 cm long; anthers 0.6-0.8 cm long; connective slightly decurrent, basally with 2 ventral tubercles and a dorsal short spur. Ovary half-inferior, ovoid, apex with membranous crown; crown 5-lobed, lobe margins ciliate; placentas short stalked. Capsule funnelform cup-shaped, apex truncate, dehiscence poricidal; crown woody, 5-lobed, exserted ca. 0.2 cm beyond calyx, margin irregularly denticulate. Seeds more than 100, light brown, ca. 0.1 cm long.

Phenology.

Flowering in October-November, fruiting in January-March.

Etymology.

The specific epithet combined from ex - (lacking) and alatus (winged) which refers to the wingless capsules.

Vernacular name.

Hui Zhou Hu Yan Hua (Chinese pronunciation); 惠州虎颜花 (Chinese name).

Distribution.

Tigridiopalma exalata grows in damp, shaded but well-drained places in broad-leaved forests, in elevations between 100 m and 350 m in Huizhou, Guangdong Province, China (Fig. 4 ).

Preliminary conservation assessment.

About 1000 mature Tigridiopalma exalata individuals from one locality have been found in less than 60 km2 up to now. This area can be classified as the extent of occurrence. The plants are not well protected in a Forest Park and the populations are severely fragmented. This species has horticultural potential as an ornamental plant. According to the IUCN Standards and Petitions Committee (2019), a category of Endangered (EN) is recommended for Tigridiopalma exalata for the present.

Paratype.

China. Guangdong: Huizhou, Longmen, on damp slopes of ravines in broad-leaved forests, 121 m, 25 November 2017, S.Jin Zeng 397 (CANT!, IBSC!).

Figures

Figure 3. Tigridiopalma exalata S. Jin Zeng, Y. C. Xu & D. F. Cui: A plant B leaf base, abaxial view C opening flower, front view D petal, front view E longer stamens, side view F longer stamen, front view G short stamens, side view H short stamen, front view I opening flower, longitudinal section J hypanthium, with attached style, longitudinal section. Scale bars: 5 mm. Drawn by Ding-Han Cui.

Figure 4. Comparison of Tigridiopalma exalata and T. magnifica: A-E Tigridiopalma exalata a-e T. magnifica A, a flowering plants B, b leaf bases, abaxial view C, c flowers, front view D, d stamens, side view E, e infructescences, side view. Photographed by Si-Jin Zeng.