Eutrema nanum G.Q.Hao, J.Quan Liu & Al-Shehbaz

Hao, Guoqian, Al-Shehbaz, Ihsan A., Zhang, Lei, Guo, Xinyi, Bi, Hao, Xu, Songbai & Liu, Jianquan, 2018, Eutremananum (Brassicaceae), a new species from Chola Shan, Southwest China, PhytoKeys 109, pp. 17-25 : 17

Eutrema nanum G.Q.Hao, J.Quan Liu & Al-Shehbaz sp. nov.

Type.

China. Sichuan: Chola Shan, 31°55'32"N, 98°54'35"E, 4500 m elev., 16 August 2014, Liu & Hao 14091 (Holotype, SZ). Figures 1, 2.

Description.

Herbs perennial, 3-6 cm tall, glabrous or puberulent; caudex slender, ca. 3-5 mm long. Leaves basal, rosulate, 20-25 per caudex; petiole 13-20 mm long, slender at base, glabrous or with few trichomes; blade oblong, elliptic, obovate, spatulate, 6-10 × 3-4 mm, fleshy, glabrous or abaxially pubescent with trichomes, 0.3-0.6 mm long, base subattenuate, to cuneate, margin entire, apex obtuse to subrounded. Pedicels slender, 18-23 mm long at anthesis, not elongated in fruit, not persistent. Flowers 5-8 per plant; sepals ovate to oblong, 1-1.5 mm long; petals white, broadly obovate to spatulate, blade 2-3 ×1– 2 mm, persistent to fruit maturity, claw-like base 0.5-1 mm long. Ovules 2-4 per ovary. Fruit latiseptate, dehiscent, ovate to oblong, somewhat curved, 4-7 × 2-3 mm; valves nearly flat, extending along part of fruit length; gynophore 0.1-0.3 mm long; replum 0.3-0.4 mm wide; style 0.6-1 mm long. Seeds broadly ovate, brown, plump, 2-4 per fruit, 1.4-2 × 0.6-1 mm.

Eutrema nanum is morpholgically most similar to E. nepalense , from which it is readily distinguished by having oblong, elliptic, obovate to spatulate leaves, glabrous sepals and ovate to oblong larger fruit 4-7 × 2-3 mm with flattened, glabrous valves. In contrast, E. nepalense (https://www.gbif.org) has suborbicular to broadly ovate leaves, puberulent sepals and ovoid to subglobose smaller fruit 2-3 × 1.8-2 mm with rounded, puberulent valves. Eutrema nanum was only found with around 100 individuals along a stream in a valley about 2 kilometres from the Chola Shan peak, whereas E. nepalense occurs across Himalyas Mountains in Bhtan, China, Nepal and India.

Phenology.

Flowering: June–August. Fruiting: August–September.

Distribution and habitat.

Eutrema nanum is currently known only from Chola Shan, part of Hengduan Mountains in West Sichuan, China (Fig. 3). It grows under rocks by streams close to glaciers, damp or gravelly scree, wet sand at a very high elevation of 4500-4600 m.

Paratype. China. Sichuan: Chola Shan, 31°55'32"N, 98°54'35"E, 4500 m elev., Liu 17124 (SZ).