Glochidion liangkwangense Gang Yao, sp. nov.
Creators: name: Yao, Gang
name: Luo, Shixiao
name: Huang, Jiuxiang
name: Song, Zhuqiu
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Phyllanthaceae
Glochidion
Glochidion liangkwangense

description: Glochidion liangkwangense Gang Yao & Z.Q. Song, sp. nov.
(Figures 1, 3)
Diagnosis:— Glochidion liangkwangense is most similar to G. anthopotamicum in morphology, but differs from the latter by its lateral veins in leaf blades elevated abaxially (especially for leaf blades grow at the lower part of branchlets) (vs. not elevated abaxially); sepals erect and usually extend outward (vs. spreaded or even reflexed at the upper part, and jointly formed a urceolate shape at the lower part), glabrous or subglabrous along the midrib (vs. densely pubescent); sepals of female flowers in 2 series, but different in shape and size (vs. in 2 series but subequal in both of shape and size); disc segments short and spatulate to slightly T-shaped (vs. long and linear); capsules triangular-globose (vs. globose).
Type:— CHINA. Guangdong Province, Yangchun Hsien, Kongtongyan, in limestone hills, elevation ca. 66 m, 22.18553574°N, 111.74617918°E, 2April 2024, Gang Yao & Zhu-Qiu Song 2024010 (holotype: IBSC1025532; isotypes, IBSC1025533, IBSC1025534; Figure 3).
Description:—Shrubs, 0.8–2.5 m tall, erect, monoecious; stem gray-brown; branches terete, subglabrous to pubescent, green when young. Stipules short, 1–3 mm long, usually triangular at lower part of branches and narrowly triangular at upper part of branches. Petiole 4–6 mm long, subglabrous. Leaves simple, alternate, distichous; leaf blades 2.0–7.0 × 1.0– 3.5 cm, usually coriaceous, broadly ovate or elliptic, usually glabrous, or puberulent on the vines abaxially when young; leaf blades at upper part of branches usually smaller, lateral veins in 5–7 pairs; leaf blades at lower part of branches usually larger, 3.0–7.5 × 2.0–5.0 cm, lateral veins in 5–9 pairs; leaf blades margin entire, slightly revolute, apex acute to acuminate, base broadly truncate to sub-rounded, or rarely cordiform, usually glaucous abaxially in individuals habituated at lower elevations; midrib and lateral veins flattened above, slightly elevated below (especially the midrib), usually anastomosing near margin. Male flowers clustered axillary, usually inserted at the lower part of branches; pedicles 3.0– 4.5 mm long, glabrous or sparsely pubescent; sepals 5, 3.0–3.5 × 1.0– 1.5 mm, erect and usually extend outward, imbricate, yellowish-white, midrib elevated on abaxial surface, narrowly triangular or ovatetriangular and usually caudate at apex, glabrous or rarely sparsely pubescent; petals absent; disc segments 5, free, Tshaped, or sub-spatulate but rounded or truncate at apex, slightly greenish yellow; stamens 3, filaments connate into a terete column, anthers erect, dehiscing longitudinally, connectives apiculate. Female flowers usually solidary axillary and inserted at the upper part of branches; sepals 6, erect and usually extend outward, imbricate, in 2 series, inner ones ovate and with a caudate at apex, outer ones narrowly triangular, usually glabrous; petals absent; disc segments 6, free, extended outside, T-shaped or slightly expand at apex, slightly greenish yellow; ovary 3-locular, pubescent at least at the upper part; styles 3; stigmas evidently bifid. Capsules 5–7 mm in diam., globose-triangular, smooth, brownish when mature, fruiting pedicels 2–3.5 mm long. Seeds 2–2.6 × 3–3.5 mm, obscurely laterally compressed, dark brownish when mature.
Additional specimens examined (paratypes): — CHINA: Guangdong Province, Luoding Hsien, Chuanbu Town, Hua-Shing Chiu 561 (IBSC0325784); Yangchun Hsien, Kongtongyan, Kongdongyan, elevation 300 m, 24 November 1991, Nian Liu et al. 3052 (IIBSC0325785); Yangchun Hsien, 10 September 1956, Chi Wang 42121 (IBK00168390, IBSC0325786); Yangchun Hsien, Kongtongyan, 16 October 1935 Chi Wang 38481 (IBK00168392, IBSC0325782, IBSC0325780, IBSC0325781, IBSC0325783). Guangxi Province, Du’an Hsien, Shangfu, 3 July 1957, Yin-Kun Li P01570 (IBSC0325794, KUN1294369); Jingxi Hsien, Longyangshan, 26 Augst 1935, Sik-Pang Ko 55629 (IBK00168381, IBK00168387, IBSC0325793); Lingyun Hsien, elevation 956 m, 15 October 2013, Lingyun Expedition 451027131015013 (GXMG0117289, GXMI063810); Liujiang Hsien, elevation 126 m, 10 Augst 2018, Liujiang Expedition 450221180810025LY (IBK00425489); Long’an Hsien, Longhushan, 1 September 2011, elevation 220 m, Jin-Cai Yang et al. LH0459 (IBK00306774); Longzhou Hsien, Paotai Mountain, 4 October 1958, Huan-Qi Li 40064 (IBK00168394, KUN1294370); Nandan Hsien, 7 September 2024, Gang Yao YGGXTE2024090701 (IBSC).
Habitat and distribution:— Glochidion liangkwangense is found in multiple localities in Guangdong and Guangxi Provinces, China (Figure 4). It grows in limestone hills at elevations from 50 m to 960 m.
Phenology:—Flowering and fruiting from April to December.
Etymology:— Glochidion liangkwangense is named after its distribution regions, in Guangdong and Guangxi Provinces, China.
Chinese name: — Liang Guang Zhu Zi Mu (两ḞȕƗ†)
Preliminary conservation status:—It is considered here as LC according to current information and the IUCN Red List criteria (IUCN Standards and Petitions Committee, 2019) for its wide distribution regions and multiple wild populations and individuals.
Morphological relationships:—Morphologically, the new species is characterized by its sepals that are caudate at apex and have elevated midrib abaxially (Figure 1F), spatulate to slightly T-shaped glands in flowers (Figure 1E, G, I), as well as extended connectives of anthers. All these characters indicate that it is a member of the traditionally circumscribed Phyllanthodendron. Furthermore, the lack of a pedicelled clustered fascicle indicates that the new species belongs to the subgenus Phyllanthodendron in the newly circumscribed Glochidion, as defined by Bouman et al. (2022). In Bouman et al. (2022), five species were accepted in the subgenus Phyllanthodendron, and the sixth species of the subgenus, viz. G. yangchunense Z.Q. Song & Gang Yao (2024: 230), was described recently from Yangchun Hsien, Guangdong Province, China. The new species most resembles G. anthopotamicum in morphology, and specimens of the new species are deposited mainly under the latter name in most herbariums in China. However, results from the present study show that the two species could be easily distinguished by characters of flowers and capsules. The new species has erect sepals that are usually extend outward (Figure 1E‒J), glabrous or subglabrous along midrib of sepals (Figure 1H, J), 2 series of sepals of female flowers different in shape and size (Figure 1E, I), spatulate to slightly Tshaped disc segments in flowers (Figure 1G, I), styles usually swollen at apex, capsules that are triangular-globose in shape (Figure 1K, L). In contrast, G. anthopotamicum has sepals that are spreading or even reflexed at the upper part but jointly formed an urceolate shape at the lower part (Figure 2C‒G), midrib of sepals that are densely pubescent (Figure 2E, F), 2 series of sepals of female flowers subequivalent in both of shape and size (Figure 2G), linear disc segments in flowers (Figure 2D, G), styles not swollen at apex (Figure 2G), and capsules that are globose in shape (Li 1994). Additionally, the new species is also similar to G. yangchunense morphologically in having sepals of flowers that are extend outward and T-shaped disc segments in flowers (Song and Yao 2024). However, the new species differs from the latter by its smaller leaves at the upper part of branchlets and larger leaves at the lower part of branchlets (Figure 1C) (vs. larger leaves at the upper part of branchlets and smaller leaves at the lower part of branchlets), sepals caudate or narrowly acuminate at apex (Figure 1E‒J) (vs. sepals acute to shortly acuminate at apex), lateral veins in sepals are absent (Figure 1E, G, I) (vs. present), smaller capsules (5–7 mm in diameter) that are triangular-globose in polar view (Figure 1K, L) (vs. 8–10 mm in diameter and subglobose in polar view). Additionally, the new species also much differs from other members accepted currently within the subgenus Phyllanthodendron.
Due to the lack of specialized literature for the identification of Glochidion subg. Phyllanthodendron species occurring in Asia, and considering the great similarity between them, it provides a key to identify them.
description: Published as part of Yao, Gang, Luo, Shixiao, Huang, Jiuxiang & Song, Zhuqiu, 2024, Glochidion liangkwangense (Phyllanthaceae), a new species from Guangdong and Guangxi Provinces, China, pp. 95-101 in Phytotaxa 677 (1) on pages 96-100, DOI: 10.11646/phytotaxa.677.1.6, http://zenodo.org/record/14522098