Thysanotus tibeticum H.P.Deng & G.H.Liu

Liu, Guanghua, Lan, Xiaozhong, Zuo, Youwei, Yang, Yubing, Li, Jiaxi, Liao, Xiaomin, Zhang, Jiabin & Deng, Hongping, 2024, Thysanotus tibeticum (Asparagaceae), a new species from Tibet, China, Phytotaxa 642 (4), pp. 285-290 : 286

Thysanotus tibeticum H.P.Deng & G.H.Liu , sp. nov. ( Figs 1 , 2 )

Type:— CHINA. Tibet, Jiali County, Zhongyu Township, Xiongqu River , ca. 3777 m a.s.1., ca. 93°47′51.8′′ E, 30°36′30.15′′ N, 6 August 2014, X.Z. Lan 542422140 806355LY (holotype, SWCTU!) ( Fig 3 ).

Description:—Rhizome short, stout. Leaves many, tufted, narrowly linear or flattened filiform, (4) 15–22 cm × ca. 1–2 mm, rigid, glabrous. Scape slightly longer than leaf, bearing a terminal umbel. Umbel 2–5-flowered; bract 1, membranous. Pedicels 9–35 mm, erect. Tepals 6, free, oblong, 9–10 × 2.5–3 mm; inner tepals slightly narrower than outer tepals, entire. Stamens 6; anthers equal or subequal in length, dehiscing by full-length slits. Ovary superior, elliptic, 3 × 1.8 mm; 3–l ocular; ovules usually 2 per locule; style straight, 0.8 mm; stigmas small.

Etymology:—The epithet tibeticum was derived from the name of the Tibet Autonomous Region where T. tibeticum was collected.

Vernacular name:—Xī Zàng Yì Ruǐ Cǎo (hḡ异ğặ). The first two words, “Xī Zàng”, mean Tibet Autonomous Region and the following three words, “Yì Ruǐ Cǎo”, mean Thysanotus in Chinese.

Distribution and habitat:— Thysanotus tibeticum is distributed in bushes along the river in Xiongqu Valley, Zhongyu Township, Jiali County, Tibet, with an elevation of 3777 m. Associated vegetation includes Nepeta hemsleyana Oliver ex Prain , Salix wilhelmsiana M. B., Lyonia ovalifolia var. hebecarpa (Franchet ex Forbes & Hemsley) Chun , Oxalis corniculata L., Sagina japonica (Sw.) Ohwi , Artemisia sieversiana Ehrhart ex Willd. , Fragaria nubicola (J.D. Hooker) Lindley ex Lacaita , Polygonum capitatum Buch. -Ham. ex D. Don, Pternopetalum subalpinum Hand. -Mazz., Anaphalis lactea Maxim. and Ranunculus nephelogenes Edgeworth. In addition, Thysanotus tibeticum often found growing under shrubs, very rarely growing in the open.

Phenology:—Flowering period July to August; fruiting period August to October.

Similar species: —After comparison with specimen material, T. tibeticum was found to be similar to both T. chinensis and T. patersonii Brown (1810: 1802) . A comparison of morphology of the three species is provided in Table 1.

T. tibeticum can be distinguished from T. patersonii by the tepals (inner tepals slightly narrower than outer tepals, entire in T. tibeticum vs. inner tepals fimbriate-denticulate at margin proximally in T. patersonii ), inflorescence (umbels 2–5-flowered in T. tibeticum vs. flowers occurring singly on branches in T. patersonii ). In shape of flowering stems, T. tibeticum is erect or spreading, while T. patersonii is twining or prostrate. Lastly, the type of roots also exhibits obvious differences between T. tibeticum and T. patersonii , as T. tibeticum has roots fibrous, while T. patersonii has roots tuberous.

T. tibeticum can be distinguished from T. chinensis , based on its tepals (inner tepals slightly narrower than outer tepals, entire in T. tibeticum vs. inner tepals fimbriate-denticulate at margin proximally in T. chinensis ), anthers (equal or subequal in length in T. tibeticum vs. distinctly three long and three short in T. chinensis ), pedicels (erect, without articulate near base in T. tibeticum vs. nodding, articulate near base in T. chinensis ), inflorescence (umbels 2–5- flowered, only one bract in T. tibeticum vs. umbels 4–10-flowered, multiple bracts in T. chinensis ).

Additional specimens examined:— T. chinensis : VIETNAM. Indochine Tonkin, Hông-Gay, in flower, 4 December 1901, S. N. Jeanplong L 0041490 (holotype, L) ; CHINA. Macao, in flower, 10 November 1907, K. K. Tsoong 01791811 ( PE) ; Fujian , in flower, 18 November 1956, C. J. Zeng 003193 ( AU) ; Guangxi , in flower, 17 January 2011, Y. S. Huang, C. R. Ling IBK00220460 ( IBK). T. patersonii : AUSTRALIA. George Town, in flower, 20 November 1842, R. C. Gunn K000794791 (neotype, K) ; in flower, 3 October 2007, L. Q. Li 01723916 ( PE) .

Notes:—At present, T. tibeticum is the only one found to be distributed on the Qinghai-Tibet Plateau and differs greatly in elevation from other species in Thysanotus . Moreover, the new species grow under riverside shrubs in the Qinghai-Tibet Plateau, while the other species of the genus grow in the sandy grasslands, with significant habitat differences.

The etymology of Thysanotus derives from the Greek thysanos (a fringe), in reference to the fimbriate petals. Interestingly, the new species has entire inner tepals, which are distinct from others in Thysanotus . The above characteristics in addition to the disjunct geographical distribution patterns of the new species, coupled with significant morphological differences from the other species of the genus, are of great significance for studying the origin and systematic evolution of Thysanotus .

Figures

FIGURE 1. Thysanotus tibeticum. A. Habitat; B. Population; C. (lateral view); D. Flower (top view); E. Unfolding of flowers; F. Stamens; G. Anther; H. Pistil. (Photographs by Guang–Hua Liu & Xiao-Zhong Lan).

FIGURE 2. Thysanotus tibeticum. A. Plant; B. Inflorescence; C. Sepals, petals and stamens; D. Pistil. (Drawn from the type plant by Xiao–Shuang Zhang).

FIGURE 3. The type location of Thysanotus tibeticum (▲).