Rorippa daguanensis W. Zhang & K. Zhao, 2025

Zhang, Wei, Xiang, Xiao-Yan, Han, Ting-Shen, Shao, Jian-Wen & Zhao, Kai, 2025, Rorippa daguanensis (Brassicaceae), a new species from eastern China, PhytoKeys 253, pp. 189-198 : 189-198

Rorippa daguanensis W. Zhang & K. Zhao sp. nov.

Figs 4 , 5

Type.

China • Anhui, Anqing City, Daguan District, Qili Lake , 30°29'33.22"N, 116°54'31.27"E, alt. 7 m, 18 April 2022, Wei Zhang & Kai Zhao ZW 20220418 (holotype: ANUB!; isotypes: ANUB!; isotypes: CSH!) (Fig. 5 ) .

Diagnosis.

Rorippa daguanensis is similar to R. dubia and R. cantoniensis , but it can be readily distinguished from R. dubia by inconspicuous stems (vs. conspicuous stems), oval silicle 5.5–6.5 mm × 2.5–3.5 mm (vs. linear silique 2.5–4 cm × 0.7–0.9 mm) and can be differentiated from R. cantoniensis by the absence of petals and bracts on the flowers (vs. flowers with petals and bracts) and wrinkled pericarps (vs. smooth pericarps).

Description.

Herbs annual, 3–8 cm tall, glabrous throughout. Stems mostly inconspicuous, with a few erect or decumbent. Leaves petiolate, 10–20, forming an open rosette, pinnatisect or almost bipinnatisect, 2–10 × 1–2 cm, lateral lobes 3–10 on each side of mid-vein, 2–10 × 1–4 mm, incised, dentate or entire. Racemes ebracteate. Fruiting pedicels stout, ascending, 1–4 mm. Sepals purple or green, ascending, oblong or subelliptic, 0.8–1.2 × 0.2–0.4 mm. Petals absent. Filaments 0.8–1.2 mm; anthers oblong, 0.1–0.3 mm. Ovules 100–200 per ovary. Fruit broadly or narrowly oblong, 5.5–6.5 × 2.5–3.5 mm; pericarp wrinkled, valves thin papery, veinless; style 1–1.4 mm. Seeds reddish-brown, ovate or oblate, foveolate, 0.2–0.4 × 0.2–0.4 mm.

Phenology.

Flowering and fruiting from February to November.

Chinese name.

Dà Guān Hān Cài (大观蔊菜).

Etymology.

The specific epithet ‘ daguanensis ’ refers to the type specimen collection locality, Daguan District, Anqing City, Anhui, China.

Distribution and ecology.

Based on our field survey, Rorippa daguanensis is currently known only from two populations: one located in Qili Lake (QLH), Daguan District, Anqing City, Anhui Province and the other in Lidu Village (LDC), Xishui County, Huanggang City, Hubei Province (Fig. 1 ). It grows in wetlands and mudflats along the Yangtze River, at elevations between 7 m and 13 m. This characteristic results in making R. daguanensis a well-defined obligate wetland indicator in its native area.

Preliminary conservation assessment.

Currently, only two populations of Rorippa daguanensis were recognised in eastern China, each consisting of approximately 300 individuals. The estimated Extent of Occurrence (EOO) for this species is 15 km 2 and the Area of Occupancy (AOO) is 0.05 km 2. In addition, its living environment has been significantly impacted by seasonal floods and human activities over an extended period. Therefore, based on IUCN Red List Categories and Criteria ( IUCN 2024), the conservation status of this new species is evaluated as ‘ Vulnerable’ (VU) as it meets criteria D 1 and D 2.

Figures

Figure 1. Known geographical distribution of R. daguanensis in China (red triangle).

Figure 4. Morphological characters of R. daguanensis sp. nov. A plant in flowering B plant in fruiting C apetalous flower D inflorescence E infructescence F transection of fruits G seed H habitat I leaf morphology.

Figure 5. Holotype of R. daguanensis sp. nov. (ANUB 100099).