Aster xuelinii Z. F. Bai 2025, sp. nov.

Aster xuelinii Z. F. Bai sp. nov. Fig. 1 Type. China • Gansu: Hui County, damp stone wall, elev. 800–1100 m, 9 August 2024, Zengfu Bai & Xuelin Chen 20240043 (holotype NWTC!; isotypes GAUF!). Diagnosis. This new species resembles A. dolichopodus superficially. Both have linear – lanceolate cauline leaves and long pedicels. However, the new species differs by having fewer than 15 ray florets (vs. 19–26), stems that are caespitose, pendent, or rarely ascending, and slender (vs. simple, sometimes caespitose, erect, stout stems). It grows in moist habitats (vs. dry habitats). Description. Perennial herbs, 30–70 cm tall. Rhizomes short, slightly thick, woody. Stems caespitose, pendent, or rarely ascending, slender, unbranched except for inflorescence, shortly pubescent, with many basal rosette leaves and cauline leaves. Rosette leaves lanceolate, 4–10 × 0.8–1.2 cm, apex acute, base gradually narrowing, strigose, margin serrately one- to two-toothed, petiole 3–5 cm long; lower cauline leaves similar to rosette leaves, sessile, narrowly lanceolate, 4–8 × 0.6–1.4 cm, margin entire or 1 - toothed, base gradually narrowing, apex acute, both surfaces of the leaf sparsely scabrous; middle to upper leaves sessile, lanceolate to linear-lanceolate, 3–7 × 0.4–0.7 cm, entire or rarely with a single tooth. Synflorescence leaves lanceolate to linear-lanceolate, 0.5–3 × 0.1–0.4 cm. Capitula 1-6 in terminal corymbiform synflorescences, sometimes solitary; peduncles 6–9 cm long, with linear ca. 2–3.5 mm in diam. bracts. Involucres hemispherical, ca. 5 mm long, 7–15 mm in diameter; phyllaries 5–7 - seriate, imbricate, coriaceous, with broadly scarious and shortly ciliate. Outer bracts shorter than inner ones: outer ones lanceolate, only the outermost basally covered with short scabrous hairs; inner ones oblanceolate. True ray 12–14, pale purple, glabrous, 5–9 × 1.2–2 mm; corolla tube 4–6 mm long, apex slightly 2–3 - lobed. Disk florets numerous, perfect; tubular yellowish-green, tube 3–4 mm long, glabrous, shallowly 5 - lobed; lobes narrowly triangular. Pappus 1 - seriate, erect and persistent, off-white in color with minute pubescence adaxially, reaching the base of the corolla lobes or equaling the tube in length. Achenes of both florets similar, narrowly oblong, ca. 2 mm long and 1 mm wide, strigose. Phenology. Flowering and fruiting from late June to September. Etymology. This distinctive designation honors the substantial contributions made by Chinese botanist Xuelin Chen to botanical diversity surveys in Gansu Province over many years. Hence, the Chinese name “ 学林紫菀 (xué lín zĬ wăn) ” is suggested. Distribution and habitat. Aster xuelinii is only known from its type locality, Hui County, Gansu Province, China. This new species grows on moist rock slopes at elevations of 800–1000 meters (Fig. 2). Systematic position. Based on molecular phylogenetic analyses, the new species is closely related to A. taliangshanensis, and both species are recognized as members of Aster sect. Aster. in Flora of China (Chen et al. 2011) (Fig. 3).