Mouretia hainanensis (H. S. Lo) Z. Q. Song & D. X. Xu comb. nov.

Figs 1, 2, 3

Type.

China • Hainan Province, Ledong County, Jianfeng [Jianfengling], Tianchi, in valley, 25 April 1982, Q. Huang 820455 (holotype: IBSC 0590313!; Fig. 1 A).

Description.

Perennial herbs, 10–25 cm tall, sub-erect to procumbent, terrestrial. Stem unbranched or little branched, terete, hirtellous or villosulous when young, glabrescent when mature, 4–6 mm in diameter, with usually 3–17 mm long internodes, without straw-yellow and corky bark. Leaves simple, opposite, generally isophyllous; petiole 1–6 cm, villosulous; blade slightly succulent, chartaceous when dry, adaxially green, abaxially grayish green, oblanceolate or narrowly elliptic, 5–12 × 3–4 cm, adaxially glabrous, abaxially villous to villosulous, base acute to attenuate, apex acute or weakly acuminate; secondary veins 9–12 pairs. Stipules interpetiolar, persistent, entire, ovate to elliptic, 5–10 × 3.5–6 mm, puberulent outside, obtuse, green, with undulate margins. Inflorescences terminal, solitary or in groups of three on a short common peduncle, capitate or subcapitate, densely villosulous, pedunculate; peduncles 1.5–4 cm long, villosulous; heads ca. 1.5 × 1.5 cm, with 7–10 flowers; bracts lanceolate to ovate, large at base of peduncles, 3.8–10 × 1.6–1.8 mm, small at base of pedicel, 1.3–2.3 × ca. 1 mm, sometimes apparently reduced. Flowers bisexual, homostylous, 5 - merous, 10–12 mm long, subsessile to sessile, rarely with a 3 mm long pedicel. Calyx densely hirtellous, campanulate; tube whitish, ca. 3.3 mm high, ca. 3 mm wide; lobes ovate-triangular, 2.2–2.7 × 1.6 mm. Corolla aestivation valvate. Corolla white, tubular, outside hirtellous; tube 3.5–3.8 mm long, ca. 1.3 mm wide, inside with a ring of hairs at the middle; lobes narrowly oblong, revolute, ca. 4.5–5 mm × 1 mm. Stamens inserted near the middle of the corolla tube, exserted; filaments 3.5–3.8 mm long, white; anthers dorsifixed near base, narrowly oblong, 1.6–1.8 × 0.7 mm, yellow, opening by longitudinal slits. Ovary 2 - locular with numerous ovules; disk concave; style filiform, ca. 8.7 mm long, white, glabrous; stigma exserted, capitate, and very shortly 2 - lobed, densely papillate. Fruits capsular, obdeltoid, ca. 4 mm long, crowned by the persistent calyx lobes, dehiscent through an apical lid formed from the disk portion. Seeds numerous, angular, black, 0.3–0.5 mm in diameter.

Phenology.

Flowering from April to May and fruiting from May to July.

Distribution and habitat.

Mouretia hainanensis is currently known from Ledong County and Sanya City, Hainan Province, China (Fig. 6), and it grows in the understory of moist ravine forests, usually along streams at 650–800 m elevation.

Additional specimens examined.

China • Hainan Province, Ledong County, Jianfeng [Jianfengling], in wet environment, 1 June 1982, Q. Huang 820619 (IBSC 0472203!); • Hainan Province, Ledong County, Jianfeng [Jianfengling], by stream, 13 April 1982, Q. Huang 820036 (IBSC 0472204!); • Hainan Province, Ledong County, Jianfengling, in ravine, alt. 800 m, 29 May 1959, C. F. Wei 122502 (IBSC 0472205!); • Hainan Province, Ledong County, Jianfengling, Feishuikeng, in ravine, 9–10 April 1955, H. Y. Liang 68605 (IBSC 0472206!); • Hainan Province, Ledong County, Jianfengling, by stream, alt. 700 m, 1 October 1957, H. D. Zhang 3517 (IBSC 0472207!); • Hainan Province, Ledong County, Jianfengling, in ravine, dense forest, white flowers, 9 April 1988, B. H. Chen 745 (IBSC 0750022!, IBSC 0743232!); • Hainan Province, Ledong County, Jianfengling, in ravine, alt. 654 m, 8 May 2025, Z. Q. Song & D. X. Xu 2025008 (IBSC); • ibid., in ravine, alt. 840 m, 8 May 2025, Z. Q. Song & D. X. Xu 2025009 (IBSC); • Hainan Province, Ya County [Sanya City], Xiaobaokang [Baogu cun], in ravine, 11 August 1933, H. Y. Liang 62533 (IBSC 0472208!, IBK 00100422, photo!).