Elatostema weizhianum Y. L. Xu & X. F. Jin 2026, sp. nov.

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Elatostema weizhianum Y. L. Xu & X. F. Jin sp. nov. Figs 2, 3 [Elatostema sect. Elatostema ser. Papillosa W. T. Wang] Diagnosis. This new species is closely related to E. hypoglaucum B. L. Shih & Yuen P. Yang, but differs in the plants sparsely spreading hyaline-pubscent in the upper part (vs. sparsely pubescent), leaf base triplinerved, lateral veins 3–5 - pairs (vs. semi-basal triplinerved, lateral veins 2 or 3 pairs), stipules 4–6 mm long, purple-brown maculate (vs. 2–3 mm long, white-green, without minute spots), peduncles of staminate inflorescences 5–12 mm long, densely strigose (vs. 17–40 mm long, sparsely pubescent or glabrous), and achenes ca. 1 mm long, longitudinally 5 - ribbed, tuberculate (vs. ca. 0.7 mm long, base lineolate and puncticulate). The new species is morphologically most similar to E. grandidentatum W. T. Wang in sharing triplinerved leaves with coarsely triangular-serrate margins and subsessile pistillate inflorescences, but differs in having stipules purple-brown maculate (vs. stipules white, without blotches), pistillate inflorescences borne in pairs axillary (vs. solitary), receptacle glabrous (vs. pubescent), bracts ca. 20, triangular, dorsally sparsely pubescent (vs. bracts 2, oblanceolate, densely pubescent), outer bracteoles ovate-orbicular, inner bracteoles oblong-navicular, apex corniculate, dorsally pubescent (vs. bracteoles monomorphic, lanceolate, glabrous), sepals inconspicuous, degenerative (vs. 3 distinct sepals), achenes 5 - ribbed and tuberculate (vs. 13 - ribbed, smooth). Type. China, Zhejiang: • Suichang, Mt. Jiulong, Huangjiping, along valley under forest, alt. 1450 m, 3 Aug 2019, Y. L. Xu & al. 1572 (♀, holotype: ZM barcode ZMNH 0067428; isotype: ZM barcode 0067429). Description. Perennial herb, terrestrial, dioecious, with short tuberous root. Stems 10–40 cm tall, rarely branching, lower part glabrous, uppers sparsely spreading hyaline-pubescent, angulate (staminate individuals) or cylindrical (pistillate individuals). Leaves alternate, subsessile; blades membranous or thin-chartaceous, obliquely elliptic or obliquely obovate-elliptic, 2.5–17 cm long, 2–7 cm wide, apex obtuse, acute or cuspidate, base asymmetrical, broader-half round or auriculate, narrower-half cuneate, adaxially strigose, with cystoliths 0.3–0.4 mm long, abaxially hyaline-strigose, denser on veins, with cystoliths, margin triangular-dentate, ciliate, triplinerved, lateral veins 3–5 pairs. Stipules membranous, white, hyaline, linear-lanceolate, 4–6 mm long, 0.5–1 mm wide, purple-brown maculate; costa green, margin and adaxially pubescent, with cystoliths. Staminate inflorescences capitate, 1 or 2 axillary, pedunculate; peduncles 5–12 mm long, densely strigose, purple-brown maculate; receptacle sub-orbicular, ca. 4 mm in diam., glabrous, purple-brown maculate; bracts 6, with 2 larger ones opposite, broadly ovate-orbicular, ca. 4 mm long, ca. 5 mm wide, dorsally 3 - carinate, lateral 2 pairs ca. 2 mm long, ca. 2 mm wide, dorsally 1 - carinate; bracteoles linear-lanceolate, 2–2.5 mm long, 0.3–0.5 mm wide, glabrous. Staminate flowers pedicellate; pedicles ca. 2 mm long, glabrous; sepals 5, with 3 broader, ovate, ca. 1.5 mm long, ca. 0.8 mm wide, dorsally carinate, corniculate at apex, other 2 narrower, base connate; stamens 5. Pistillate inflorescences capitate, borne in pairs axillary, subsessile; receptacle sub-quadrate, 3–5 mm long, 3–5 mm wide, slightly 2–4 - lobed, glabrous; bracts ca. 20, inconspicuous, short-corniculate; bracteoles membranous, outer layers ovate-orbicular, ca. 1 mm long, ca. 1 mm wide, apex round and corniculate, inner layers oblong-navicular, ca. 1 mm long, ca. 0.3 mm wide, apex corniculate, margin and dorsally pubescent; sepals inconspicuous, degenerative stamens 3 or 4, inflexed, stigma small. Achenes ellipsoid, purple-brown, ca. 1 mm long, with 5 longitudinal ribs, tuberculate. Etymology. The specific epithet “ weizhianum ” is given in honor of Prof. Zhi Wei, a Chinese taxonomist working at the Zhejiang Museum of Natural History, who studies vascular plants, especially the family Fabaceae. Phenology. Flowering and fruiting occurs from mid-June to early August. Additional specimens examined. China, Zhejiang: • Longquan, Mt. Fengyang, Dakeng, moist place along valley, alt. 1200 m, 17 Jun 2019, Y. L. Xu & F. G. Zhang 1493 (♂, paratype: ZM). Conservation status. Endangered (EN). The new species is currently known from two localities, Mt. Jiulong in Suichang County and Mt. Fengyang in Longquan County. A total of 300 individuals in two populations grow in moist places along valleys, with an area of occupancy less than 200 km 2. Referring to the IUCN Categories and Criteria, the species is endangered (EN, B 2 (a)) and requires conservation attention and protection (IUCN 2019). Notes. According to the taxonomic revision of Elatostema by Wang (2014), among 280 species documented in China, 60 species are known only from staminate inflorescences, and 82 species are known only from pistillate inflorescences. Both staminate (Mt. Fengyang) and pistillate (Mt. Jiulong) individuals of E. weizhianum were collected. The new species has capitate staminate inflorescences and a sub-orbicular, conspicuous receptacle, which indicates that the species should be placed in E. sect. Elatostema (Wang 2014). Wang divided E. sect. Elatostema into 26 series based on leaf venation, achene shape and surface sculpture, and pedicle length of staminate and pistillate inflorescences. The new species has achenes that are longitudinally 5 - ribbed and tuberculate and should be assigned to E. ser. Papillosa W. T. Wang (Wang 2014).