Sinocrassula cuonaensis N. Wei & Q. F. Wang 2025, sp. nov.

Sinocrassula cuonaensis N. Wei & Q. F. Wang sp. nov. Figs 2, 3 Type. China • Xizang: Cuona [Tsona] City, Lebu Valley, elev. 2826 m, 27.864222, 91.796976, on the moist rocks on valley slopes by the roadside, 3 Aug. 2023, N. Wei & Z. H. Xin WN 43 (holotype: HIB!; isotypes: HIB!, PE!). Diagnostic description. Sinocrassula cuonaensis is similar to S. indica var. viridiflava, S. densirosulata, S. jiaozishanensis in having glabrous plant and long inflorescence, but its rosulate, thick, and near-cylindrical basal leaves (vs. rosulate, spatulate, not rosulate, respectively) and greenish white flowers (vs. greenish yellow, purplish red, reddish purple, respectively) differ from the others. Besides, this new species has sub-rectangular nectar scales that are similar to S. indica var. viridiflava (vs. near-rectangular oblong) and S. densirosulata (vs. spatulate-quadrate) but different from S. jiaozishanensis (vs. oblong) (Table 2). Description. Biennial herbs, lithophytic or terrestrial, 10–30 cm tall, glabrous throughout. Roots fibrous. Leaves with basal rosette, oblanceolate to obovate, 0.9–2.2 × 0.4–0.8 cm, thickness 3–4 mm wide, apex mucronate apiculate to obtuse, green or surface reddish-brown, fleshy. Stem leaves alternate, oblanceolate, 1.2–1.7 × 0.3–0.4 cm, thickness 1.5–2.5 mm wide, apex mucronate apiculate, green, fleshy. Flowering stems 15–26 cm long, creeping or somewhat pendulous. Inflorescence corymbiform panicle, ca. 1.5–5.3 cm in diameter; bracts ca. 1 × 0.4 cm, green or sometimes with red. Flowers urceolate, ca. 7.5–8.0 × 3.4–3.6 mm, greenish white, fleshy. Sepals 5, ovate-triangular, apex obtuse, ca. 1.5 × 1.1 mm, green. Petals 5, ovate-lanceolate, minutely papillate abaxially, apex usually reflexed, ca. 3–4 × 1 mm, white. Stamens 5, ca. 3 mm long; anthers orbicular, ca. 2.5 mm long, pollen yellow. Nectar scales 5, rectangular, ca. 0.7 × 0.5 mm. Carpels 5, apocarpous, ovate-triangular, ca. 3 mm. Styles erect, ca. 1 mm long. Seeds ovoid-cylindric, ca. 0.50 × 0.25 mm, surface with longitudinal ribs and transverse ridges. Phenology. Flowering from August to September. Distribution and habitat. Sinocrassula cuonaensis is currently known only from southern Xizang, China (as depicted in Fig. 4). This new species was found on moist rocks along slopes in the valley at elevations of 2500–2850 m. The general vegetation condition of the habitat is characterized by the tree layer dominated by Pinus wallichiana A. B. Jacks., Picea spinulosa (Griff.) A. Henry, and Cotoneaster sp.; the shrub layer is dominated by shrubs of the families Urticaceae and Asteraceae; and the herb layer is primarily composed of Pteridium latiusculum (Desv.) Hieron., Corallodiscus sp., and Impatiens scabrida DC. Additionally, due to the steep topography, these rock walls are less disturbed by human activities. Additional specimens examined (paratypes). China • Xizang Autonomous Region: Cuona [Tsona] City, Lebu Valley, 27.85674995°N, 91.79360947°E, alt. 2714 m, 2 October 2024, X. D. Qiu et al. XZ 08 (HIB!); • in the same area, 27.83405975°N, 91.76442437°E, alt. 2502 m, 2 October 2024, X. D. Qiu et al. XZ 12 (HIB!). Conservation status. We found two populations with over 50 individuals in the type locality of Sinocrassula cuonaensis. The similar habitats have been thoroughly surveyed in the vast southern region of Xizang and the surrounding Bhutan and India. Further surveys in these regions could potentially reveal additional populations and individuals yet to be recorded. Therefore, we temporarily classify the species as Data Deficient (DD) according to the IUCN Red List Categories and Criteria (IUCN 2024). Etymology. The specific epithet ‘ cuonaensis ’ refers to Cuona City, where the species was discovered. A key for identification of the genus, including the new species, is compiled and provided below.