Glochidion yangchunense Z.Q. Song & Gang Yao, 2024

Song, Zhu-Qiu & Yao, Gang, 2024, Glochidion yangchunense (Phyllanthaceae), a new species with discoid flowers from Guangdong Province, China, PhytoKeys 239, pp. 229-238 : 229

Glochidion yangchunense Z.Q. Song & Gang Yao sp. nov.

Figs 1 , 2 阳春珠子木

Type.

China. Guangdong Province, Yangchun City, Chunwan Town, Nali village , in limestone hills, 22.410809°N, 111.932152°E, alt. 200 m., 5 July 2023, Gang Yao & Zhu-Qiu Song YGGDYC2023070501 (holotype: IBSC [IBSC1010886], Fig. 2A ; isotypes: IBSC [IBSC1010887, IBSC1010888, IBSC1010889, IBSC1010890, IBSC1010891, IBSC1010892, IBSC1010893]) .

Diagnosis.

Glochidion yangchunense resembles Glochidion anthopotamicum (Hand.-Mazz) R.W. Bouman in general morphology, but much differs from the latter by its glabrous flowering branches (Fig. 1G, I ) (vs. pubescent flowering branches; Fig. 3C-F ), sepals with lateral veins (Fig. 1F, H ) (vs. sepals without lateral veins; Fig. 3D-F ), sepals jointly formed a discoid shape (Fig. 1F-I ) (vs. sepals jointly formed a urceolate shape; Fig. 3D-F ), T-shaped disc segments (Fig. 1F, H ) (vs. linear disc segments; Fig. 3D ), and short stipules (ca. 1 mm vs. 3 mm long).

Description.

Shrubs, 0.5-2.5 m tall, erect, monoecious; stem gray-brown; branches glabrous and terete, but sparsely gray puberulent and slightly angular when young. Stipules ovate-triangular, ca. 0.8 × 0.6 mm, usually caducous. Petiole 2.5-4 mm long, sparsely gray puberulent when young. Leaves simple, alternate, distichous; leaf blades papery to leathery, broad elliptic, elliptic, ovate, or narrowly ovate, length/width ratio 1.5-2.1, glabrous but puberulent on vines below when young; leaf blades at upper part of branches usually larger, 3.5-5.2 × 1.5-3 cm, lateral veins in 6-8 pairs; leaf blades at lower part of branches usually smaller, ca. 1.8-2.5 × 1.2 cm, lateral veins in 3-5 pairs; leaf blades margin entire, slightly revolute, apex acute, rarely acuminate, base sub-rounded; midrib and lateral veins flattened above, slightly elevated below, anastomosing before margins. Inflorescences axillary, 2-4-flowered; male flowers usually inserted at the lower part of branches, female flowers inserted at the upper part; flowers sometimes crowded in long-pedicelled clustered fascicles; pedicels 6-8.5 mm long, enlarged at apex. Staminate flower: sepals 5 or rarely 6, imbricate, forming a discoid shape, green yellow, midrib elevated on abaxial surface, ovate, 3.3-4.3 × 1.4-2.3 mm, outer sepals lanceolate, inner ones ovate, glabrous; petals absent; disc segments 5, rarely 6, free, T-shaped and expand at apex, slightly greenish yellow; stamens 3, or rarely 4; filaments connate into a terete column, anthers erect, dehiscing longitudinally, connectives usually apiculate. Pistillate flower: sepals 6, imbricate, forming a discoid shape, glabrous, size as in staminate flower; petals absent; disc segments 6, free, T-shaped and expand at apex, slightly greenish yellow; ovary 3-locular; styles 3; stigmas evidently bifid. Capsules subglobose, 8-10 mm in diam., smooth outside, brownish when mature, fruiting pedicels 6-9 mm long, enlarged at apex. Seeds obscurely 3-angled or laterally compressed, ca. 4.2-4.5 × 2.7 mm, brownish when mature.

Phenology.

Flowering and fruiting from March to December.

Distribution and habitat.

Glochidion yangchunense is currently known only from the type locality, Chunwan Town, Yangchun City, Guangdong Province, China (Fig. 4 ), and it grows in limestone hills usually at elevations over 200 m.

Etymology.

The specific epithet refers to the type locality, Yangchun City in Guangdong Province, China, a hotspot for biodiversity research in Guangdong Province, where multiple new taxa of plant (e.g. Ilex yangchunensis C.J. Tseng, Chiritopsis subulata var. yangchunensis W.T. Wang, Hedyotis yangchunensis W.C. Ko & Zhang, Itea yangchunensis S.Y. Jin, Cleyera yangchunensis L.K. Ling, Alpinia stachyoides var. yangchunensis Z.L. Zhao & L.S. Xu, Symplocos yangchunensis H.G. Ye & F.W. Xing, Lithocarpus yangchunensis H.G. Ye & F.G. Wang, Croton yangchunensis H.G. Ye & N.H. Xia, Mitreola yangchunensis Q.X. Ma, H.G. Ye & F.W. Xing, Helicia yangchunensis H.S. Kiu, Primulina yangchunensis Y.L. Zheng & Y.F. Deng, and Spiradiclis yangchunensis R.J. Wang) have been described (see Song et al. 2023).

Preliminary conservation status.

This new species is known from one locality, situated in the unprotected limestone area, and more than 500 individuals (including many mature and young plants) were found. It may be considered as ‘Vulnerable’ (VU) under the IUCN (2001) categories and criteria D1.

Additional specimens examined.

China. Guangdong Province, Yangchun City, Chunwan Town, Nali village , in limestone hills, 22.410809°N, 111.932152°E, alt. 200 m., 21 March 2023, You-Sheng Chen, Zhu-Qiu Song, Bu-Yun Zhang & Zhen Wang YC 20230221 (IBSC) .

Figures

Figure 1. Glochidion yangchunense Z. Q. Song & Gang Yao A habit B detail of the apex of branches C fruiting branches D, E leaves, adaxial and abaxial surfaces, shapes and sizes F, G pistillate flower, front and lateral view H, I staminate flower, front and lateral view J branches with staminate and pistillate flowers as well as fruit K fruits and seeds. Arrows indicate disc segments.

Figure 2. Glochidion yangchunense Z. Q. Song & Gang Yao A holotype (IBSC 1010886) B isotype (IBSC 1010888). Used with permission.

Figure 3. Related species of Glochidion yangchunense Z. Q. Song & Gang Yao A-F Glochidion anthopotamicum (Hand. - Mazz.) R. W. Bouman G-L Glochidion dunnianus (H. Lev.) R. W. Bouman A, G habit B, H, I branches C-F, J-L flowers, front and lateral view H part of winged branch with stipules D, K pistillate flowers E, F, L staminate flowers. White arrows indicate disc segments and red arrow indicates stamen.

Figure 4. Distribution map of Glochidion yangchunense Z. Q. Song & Gang Yao in China (red star).