Eutrema nanum G.Q.Hao, J.Quan Liu & Al-Shehbaz, 2018

Hao, Guoqian, Al-Shehbaz, Ihsan A., Zhang, Lei, Guo, Xinyi, Bi, Hao, Xu, Songbai & Liu, Jianquan, 2018, Eutrema nanum (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).

Figures

Figure 1. Eutrema nanum. G. Q. Hao, J. Quan. Liu & Al-Shehbaz. A Plant B Fruit C Leaf trichomes.

Figure 2. Holotype of Eutrema nanum.

Figure 3. Geographical distribution of the sampled populations of Eutrema nanum and related species.