Microtropis gulinqingensis Y.M. Shui & Q. Huang, 2024

Huang, Qing, Lyu, Ling, Yang, Chong, Chen, Wen-Hong, Fan, Chang-Li, Zhang, Jin-Guo & Shui, Yu-Min, 2024, Microtropis gulinqingensis, a new dioecious species of Celastraceae from China, Phytotaxa 668 (3), pp. 293-299 : 296-297

Microtropis gulinqingensis Y.M. Shui & Q. Huang sp.nov. ( Figs. 1 & 2 ).

Type: — CHINA. Yunnan: Wenshan Zhuang and Miao Autonomous Prefecture, Maguan County, Gulinqing Township, in the limestone forest next to Bojia Village, 553 m, 103°59’38’’E, 22°43’50’’N, 30 March 2023, Y. M. Shui et al. GLQ0516-066 (holotype KUN: KUN 1608260, flowering).

Diagnosis: —This new species is similar to Microtropis discolor in having 4-merous perianth, subsessile flower, slightly semiorbicular sepals, pointed connective, and female flower with free petals, but differs in fascicle inflorescence, urceolate male flower petals, abaxially obvious lateral leaf veins, and the smooth fruit surface. This species is also similar to M. kinabaluensis in leaf size, cone-shaped ovary and smooth fruit surface, but can be distinguished by its dioecious nature, fascicle inflorescence, male flowers having connate petals fused to about two-thirds of their length, and the pointed connective.

Shrubs or small trees, dioecious.Truck erect, 1–3 m tall; bark brownish red, with small yellow lenticels. Leaves opposite, entire, coriaceous, elliptic, narrowly elliptic, or obovate, 15.2–23.0 × 5.0– 10.9 cm, base cuneate, apex acuminate or caudate, midvein concave adaxially, obvious bulging abaxially; lateral veins 7–10 pairs, concave adaxially, obvious bulging abaxially; petiole 6.2–14.2 mm. Inflorescence intercalary, axillary or terminal, fascicle, 5.4–8.1 mm long, each bearing 1–2 flowers, rarely 3–4 flowers; peduncle extremely short or absent, 1–2 mm long; pedicels 1–2 mm long, subsessile or sessile. Female flowers: sepals 4, 2 whorls, slightly semiorbicular, margin membranous, with brown erose teeth, 1.8–2.4 × 2.9–3.5 mm; petals fleshy, white, free, subovate or oblong-ovate, keeled along the middle, 4.6–5.0 × 2.6–3.8 mm; ovary awl-shaped, 1.6–1.9 mm long, 1.3–1.5 mm in diameter at the base; style obvious, stigma discoid, distinctly 4-lobed; filaments incurved, shorter than ovary, 0.1–0.2 mm long; anthers triangular, connective pointed, adnate, pollen-free, 0.6–1.0 mm long, 0.4–0.6 mm wide at the base. Male flowers: sepals 4, 2 whorls, slightly semiorbicular, margin membranous, with brown erose teeth, 1.8–2.1× 2.7–3.2 mm; petals fleshy, white, connate, urceolate, keeled along the middle, 4-lobed, connate petals fused to about two-thirds of the length, 5.3–8.0 × 4.6–4.9 mm; ovary cone-shaped, style obvious, ovule and stigma rudimentary, 1.5–1.6 mm long, 1.1–1.2 mm wide at the base; filaments incurved, extending beyond ovary, 1.5–1.6 mm long; anthers rectangular-ovate, connective pointed, adnate, pollen obvious, 1–1.1 mm long, 0.6–0.7 mm wide at the base. Fruit capsule, oval or obovate,.4–1.9 × 0.5–1.1 cm, beaked at the top, pericarp leathery, smooth. Seed 1, smooth, aril completely enveloping the seed.

Phenology: —Flowering from March to July, fruiting from July to December.

Etymology: —The specific epithet “ gulinqingensis ” is derived from the name of the type locality.

Distribution and habitat: — Microtropis gulinqingensis is only found at elevations of 500–600 m in Gulinqing Township, southeastern Yunnan, China. It was observed to mainly grow in damp areas of the limestone forest.

Additional examined specimens: — CHINA. Yunnan: Wenshan Zhuang and Miao Autonomous Prefecture, Maguan County, Gulinqing Township, in the lime mountain forest next to Bojia Village, 546 m, 103°59’34’’E, 22°43’45’’N, 17 December 2022, Y. M. Shui et al. GLQ1121 (KUN: KUN1608259, fruiting).

Conservation status:— At present, Microtropis gulinqingensis has only been found in the 25 ha Gulinqing dynamic plot, Maguan County, Yunnan Province, China. Based on our observations, we have recorded 65 wild individuals with DBH greater than 1 cm there. Additionally, no other specimens of the above species have been found in available database (CVH: https://www.cvh.ac.cn/; GBIF: https://www.gbif.org/; Tropicos: https://www.tropicos. org/) or herbaria (e.g. IBSC, K, LE, KUN, P, PE). Furthermore, fewer than 65 mature individuals have been recognized within this plot. According to the IUCN Species Endangerment Assessment Method ( IUCN 2024), the new species meets criterion D (very small or restricted population) and is classified as Endangered (EN), given that the number of mature individuals is fewer than 250.

Figures

FIGURE 1. Wild plant of Microtropis gulinqingensis. A. Plant and its habitat; B. Flowering branch (front view); C. Flowering branch (back view); D. Adaxial leaf surface; E. Abaxial leaf surface; F. Early stage of fruit development; G. Late stage of fruit development; H. Seed without aril

FIGURE 2. Flower morphology of Microtropis gulinqingensis. (A–H). Male flower; (I–P). Female flower; (A, B, I, J). Flowering branches (the arrow indicates extremely short peduncle); (C, K). Front view of the flower (the arrow indicates petals connate or free); (D, L). Side view of the flower; (E, M). Back view of the flower; (F, N). Longitudinal section of the flower; (G, O). Ovary and stamens (the arrow indicates filament); (H, P). Anther (the arrow indicates filament or pointed connective)