Spiradiclis scorpiura Y. Nong & L. Wu, 2025

Nong, You, Lei, Li-Qun, Wu, Lei, Hu, Qi-Min, Li, Ying-Jing, Qu, Xin-Cheng, Xu, Chuan-Gui & Wei, Gui-Yuan, 2025, Spiradiclis scorpiura (Rubiaceae), a new species from Guangxi, China, PhytoKeys 252, pp. 41-49 : 41-49

Spiradiclis scorpiura Y. Nong & L. Wu sp. nov.

Figs 1 –4

Chinese name.

xiē wěi luó xù cǎo (蝎尾螺序草).

Diagnosis.

Spiradiclis scorpiura is most similar to S. coccinea but is different in its densely pubescent young stems that become glabrous when older (vs. glabrous or subglabrous), its cincinnous inflorescences (vs. cymose), its triangular, 1–2 mm long, pubescent bracteoles (vs. subulate, 3–4 mm long, glabrous), its calyx puberulent outside (vs. glabrescent outside), and its capsule 3–4 mm in diam. (vs. 4.5–5.5 mm in diam.).

Type.

China • Guangxi, Daxin County, 22°54'06"N, 106°50'02"E, alt. 504 m, at the rim of the top of a sinkhole, 11 July 2024, flowering, Y. Nong NY 2024071101 ( GXMI). (Holotype: GXMI! 051187; isotype: IBK!) .

Description.

Subshrubs, perennial, 20–50 cm tall, rooting near base, stems ascending; stems densely pubescent when young but glabrous when old. Leaves opposite; petiole 1–2 mm long, sparsely pubescent; blade drying papery, adaxially olive green, abaxially yellowish green, elliptic, 3–7 × 0.5–1.5 cm, sparsely pubescent or glabrous on both surfaces, margin entire, base cuneate, apex acuminate; secondary veins 8–12 on each side of the midrib, midrib concave adaxially and prominently convex abaxially; stipules triangular, 1–2 mm long, glabrous outside, apex acute. Inflorescences terminal, cincinnous, 3–6 branched, 3–44 - flowered, pubescent; peduncles 0.6–1 cm long, pubescent; pedicels short, c. 1 mm long, pubescent; bracteoles triangular, 1–2 mm long, pubescent outside. Flowers distylous. Calyx pubescent; hypanthium portion obovate, 1–2 mm long, with 5 straight ridges; lobes 5, triangular or ovate-lanceolate, 1–1.5 mm long. Corolla purple, slenderly salverform-funnelform, glabrous or pubescent outside; tube 15–18 mm long, lobes broadly ovate to suborbicular, 6–8 mm long. Stamens 5. Style filiform, stigma clavate, 2 - lobed, lobes linear, c. 2 mm long. Long-styled flowers: corolla tube with pilose ring above stamens inside; stamens born near the base of the tube, anthers sessile or subsessile, c. 3 mm long; style c. 1.5 cm long or slightly longer. Short-styled flowers: corolla tube pubescent near the base inside; stamens born in the middle of the tube, anthers sessile or subsessile, c. 2 mm long; style c. 4 mm long. Capsules subglobose, 3–4 mm in diam., glabrescent, valves 4. Seeds numerous, angular, c. 0.2 mm in diam.

Phenology.

Flowering and fruiting in June – July.

Etymology.

The specific epithet “ scorpiura ” refers to the terminal, cincinnous inflorescences of the new species.

Distribution and habit.

Known only from southeast Guangxi, China. The species has only been found at the rim of a sinkhole at elevations of 504 m.

Preliminary IUCN red list category.

Data available for the new species, only known from the type locality and the type specimens, are insufficient to assess its conservation status. According to the IUCN Criteria ( IUCN 2022), it is considered Data Deficient (DD) until more information becomes available. Spiradiclis scorpiura is currently known from a single, relatively large population. Further collection and monitoring are necessary to allow more conclusive estimations about the rarity and vulnerability of the species.

Figures

Figure 1. Line drawing of Spiradiclis scorpiura Y. Nong & L. Wu A flowering plant B stipule C flower D long-styled flower, frontal view, showing corolla lobes and stigma E longitudinally opened long-styled flower, showing the position of the stamens and the style and stigma F longitudinally opened short-styled flower, showing the position of the stamens and the style and stigma G seed (Drawn by Xin-cheng Qu).

Figure 4. Distribution of Spiradiclis scorpiura (red circle), S. coccinea (green triangle), S. scabrida (blue heart), and S. purpureocaerulea (purple square) in Guangxi (blue triangle in insert map), China.