Homostylium motuoense (Y. L. Chen) Z. X. Fu, 2025

Chen, Xinyu & Fu, Zhixi, 2025, Resurrection of the genus Homostylium Nees for the former Aster ser. Albescentes Y. Ling (Astereae, Asteraceae), with an updated generic synopsis, PhytoKeys 259, pp. 27-66 : 27-66

6. Homostylium motuoense (Y. L. Chen) Z. X. Fu comb. nov.

Figs 15 , 16

≡ Aster motuoensis Y. L. Chen , Bull. Bot. Res. 8: 12. 1988. ≡ Sinosidus motuoensis (Y. L. Chen) G. L. Nesom , Phytoneuron 2020-64: 14. 2020. Type: China, Xizang, Mêdog, Qarasa, gudeng-ganhua, in prato lapidoso secus marginem rivuli, alt. 1100 m, Dec. 1982, S. Z. Cheng & B. S. Li 2181 (holotype, PE 02050341!; isotypes, PE 02050372!, PE 02050373!, PE 02050374!) (Suppl. material 1: figs S 35 – S 38).

Type.

China • Xizang, Mêdog, Qarasa , gudeng-ganhua, in prato lapidoso secus marginem rivuli, alt. 1100 m, Dec. 1982, S. Z. Cheng & B. S. Li 2181 (holotype, PE 02050341 !; isotypes, PE 02050372 !, PE 02050373 !, PE 02050374 !) (Suppl. material 1: figs S 35 – S 38) .

Description.

Shrubs, 53–166 cm tall. Leaves alternate, subcoriaceous, median leaves oblong-lanceolate to narrowly oblong, (1 -) 3–4 (- 6.3) × 0.7–1.4 cm, margins entire, revolute, upper leaves gradually smaller, adaxially dark green, prominent venation, glossy, abaxially densely grayish-white to white tomentose except on midvein. Capitula numerous, small, radiate, 2–3 mm in diameter, with 4–6 ray florets, in densely corymbiform synflorescences, terminal on branch tips or in upper leaf axils. Peduncles slender, densely white tomentum. Involucres cylindrical or subcylindrical, 5.3–6.4 × 2 mm. Phyllaries 4–5 - seriate, imbricate, subcoriaceous, outer phyllaries very small, ovate, ca. 1 mm long, sparsely pubescent, inner phyllaries oblong-lanceolate, 4.2–5.2 × 0.5–1 mm.

Distribution.

Endemic to China, SE Xizang, Mêdog (Fig. 15 ).

Habitat.

Riverbank slopes, roadside, and dry grassy slopes near villages. 980–1100 m.

Phenology.

Flowering and fruiting ca. November.

Etymology.

The specific epithet “ motuoense ” is derived from the place name “ Motuo ” combined with the Latin neuter suffix “ - ense ”, meaning “ from ” or “ of ”. The name refers to the species being found and collected in Motuo (Mêdog) County, located in SE Tibet, China.

Specimens examined.

China • Xizang: Mêdog , S. Z. Cheng & B. S. Li 1796 ( PE), 2075 ( PE), 2181 ( PE 02050341 , PE 02050372 , PE 02050373 , PE 02050374 ) .

Notes.

Due to transportation difficulties in Mêdog County (Xizang), we were unable to photograph, collect, or sequence Homostylium motuoense . As a result, 6 Homostylium species, excluding H. motuoense , have been sequenced and used to reconstruct phylogenetic relationship within Aster and Astereae to date ( Li et al. 2012; Zhang et al. 2015, 2019; Fu et al. 2019; Chen et al. 2024). The morphology of this species resembles H. lavandulifolium , but its leaves are narrowly oblong or elongated-lanceolate, with a glossy surface and prominent venation. The involucres are cylindrical. The ray florets 4–6, with two layers of pappus: the outer layer is very short, and the inner layer is 4 cm long, rough-haired. These characteristics make it easily distinguishable from H. lavandulifolium .

Figures

Figure 15. Distribution of Homostylium motuoense. China is centrally located on the map.

Figure 16. Homostylium motuoense (Y. L. Chen) Z. X. Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Disc floret; F. Stamen of disc floret; G. Style branches of disc floret; H. Outer pappus bristle; I. Inner pappus bristle. Drawn by Z. J. Chen.