Taxonomic studies on the genus Reevesia (Malvaceae: Helicteroideae) II: on the identity of R. orbicularifolia and a new species from southwestern Guangxi, China Author Feng, Hui Zhe 0000-0001-5693-7992 College of Life Science, Zaozhuang University, Zaozhuang 277160, Shandong, China. & fenghuizhe @ foxmail. com; https: // orcid. org / 0000 - 0001 - 5693 - 7992 fenghuizhe@foxmail.com Author Qin, Yun Rui 0000-0003-2692-9048 Guangxi Key Laboratory of Traditional Chinese Medicine Quality Standards, Guangxi Institute of Chinese Medicine & Pharmaceutical Sciences, Nanning 530022, Guangxi, China, Guangxi Institute of Chinese Medicine & Pharmaceutical Sciences, Nanning, China. & yunruiqin @ sina. cn; https: // orcid. org / 0000 - 0003 - 2692 - 9048 yunruiqin@sina.cn Author Huang, Yun Feng 0000-0001-7147-3938 Guangxi Key Laboratory of Traditional Chinese Medicine Quality Standards, Guangxi Institute of Chinese Medicine & Pharmaceutical Sciences, Nanning 530022, Guangxi, China, Guangxi Institute of Chinese Medicine & Pharmaceutical Sciences, Nanning, China. & huangyunfeng 2000 @ 126. com; https: // orcid. org / 0000 - 0001 - 7147 - 3938 text Phytotaxa 2022 2022-05-10 545 2 197 206 http://dx.doi.org/10.11646/phytotaxa.545.2.8 journal article 55610 10.11646/phytotaxa.545.2.8 6640ba9f-6c17-4b09-9c42-e5ad363eb3ab 1179-3163 6534749 Reevesia napoensis H. Z. Feng & Y. Feng Huang sp. nov. ( Figs. 3 , 4 & 5 ) Type : — China . Guangxi , Napo Country , Laohutiao Nature Reserve , 700m , 3 August 2014 , Y. Feng Huang & H. Z. Feng 70069 ( holotype GXMI , isotype IBK) . Diagnosis: — Differs from R. rotundifolia and R. orbicularis by cordate, 7-veined leaf base; 3-bracts (two linear and one elliptic-ovate); 4-lobed calyx and the glabrous petals. Description :—An evergreen tree, young branchlets terete, glabrous. Leaves petiolate, petiole 3–17 cm , terete, sparsely stellate puberulent when young, glabrous at maturity, leaf blade orbicular or ovate–orbicular, 9–40 × 8–27 cm , leathery, both sides with sparse yellowish stellate pubescence only on veins, otherwise glabrous, basal veins 7, venation adaxially conspicuously depressed, abaxially conspicuously raised, base cordate, with 3–5 teeth on upper margin, apex acute or obtuse, oblique. Inflorescence paniculate, cymose or thyrsoid, many–flowered, bracteate and flat–topped, 8–10 cm long. Pedicels ca. 3 mm , pubescent. Bracts three, two linear, ca. 0.5 × 2 mm and another one elliptic–ovate, ca. 3 × 4 mm , abaxially softly brown pubescent. Calyx connation, funnel-shaped, ca. 4 mm , abaxially softly brown pubescent, 4-lobed; the calyx lobes unequal, two lobes broadly triangular, ca. 1.5 mm , two lobes narrow triangular, ca. 1 mm . Corolla rotate, valvate; petals 5, distinct white, spatulate clawed, apex retuse or crenately 2-lobed, glabrous. Stamens 15, filaments fused to ovary stipe to form an androgynophore, upper part widening to enclose ovary; anthers are also combined in a capitate cup enclosing the ovarium, bithecous. Androgynophore ca. 1.8 cm ; anther head ca. 2 mm in diam., glabrous. Ovary 5-celled, 5-lobed; ovules 2 per locule, ascending, ovoid, ca. 1.5 mm , pubescent; style short, inconspicuous; stigma globose. Capsule yellowish puberulent, woody, loculicidally and septicidally dehiscent into 10 separate valves; obovoid-oblong, 2–3 cm , apex rounded. Seeds superposed, winged, wing developing abaxially, membranous, ca. 2 cm including wing, wing brown; endosperm reduced. FIGURE 3. Reevesia napoensis ( A) fruiting branch, (B) fruit, (C) seed, (D) capsule, (E) flower, (F) bract, (G) petal, (H) calyx. Drawn by Mr. Xincheng Qu from Y. F. Huang & H. Z. Feng 70068 (E)–(H), Y. F. Huang & H. Z. Feng 70069 (A)–(D). FIGURE 4 . Reevesia napoensis (A) habit and habitat, (B) abaxial leaves(C) Flowering twig-(D) flowers (E) fruiting twig (F) fruits, (G) dehisced capsules and seeds. FIGURE 5. Reevesia napoensis (A-B) flowering branch, (C) top of inflorescence, (D) flower, (E) flowers, (F) flower, a. petal, b. calyx, c. bract. Photographs by Ms. Dong Xin Nong. Phenology :—Flowering in May and fruiting from July to November. Distribution and ecology :—The species is known only from Napo, northwestern Guangxi , China . And it grows in wet but sunny limestone valleys. Only one small populations with 23 individuals (including only 19 mature trees) have been found in Napo. All mature trees are more than 15 m in height and less than 3 m is observed for all immature trees. The rarity of this new species may be partially due to human activity because the habitat is also suitable for cultivating cassava, tobacco and other economic plants. And the seeds are often aborted. Comparing to the number of mature trees, the number of immature trees further indicates a decreasing population trend. In addition, all these trees are distributed in a total area of approximately 0.6 km 2 . No population was found during repeated field surveys of the surrounding areas. According to the IUCN Categories and Criteria ( IUCN 2022 ), the species is classified as Critically Endangered (CR: B1 + 2c). Therefore, it will be necessary to pay close attention to the conservation of this new species. Taxonomic relationships :—The comparison with the known species of Reevesia indicates that R. napoensis is similar to R. rotundifolia Chun (1934: 269 , Fig. 6 ) and R. orbicularis in sharing the characters of the orbicular or ovate-orbicular leaf blade but it has larger phenotypic divergence with R. rotundifolia and R. orbicularis ( Table 1 ). R. napoensis differs from R. orbicularis by the leaf blades upper margin with 3–5 teeth. R. napoensis is very similar to R. rotundifolia by the leaf blades upper margin with teeth, but there are very obvious differences. R. napoensis differs from R. orbicularis by cordate base, 7-veined base (vs. truncate or rounded 3-veined, bracts three (vs. one); calyx 4- lobed (vs. 3-lobed) and glabrous petals (vs. puberulent) ( Figs. 5 & 7 ).