Elatostema setulosum W.T.Wang, 1982: 120

Fu, Long-Fei, Monro, Alexandre K., Wen, Fang, Xin, Zi-Bing, Wei, Yi-Gang & Zhang, Zhi-Xiang, 2019, The rediscovery and delimitation of Elatostema setulosum W. T. Wang (Urticaceae), PhytoKeys 126, pp. 79-88 : 83-85

Elatostema setulosum W.T.Wang, 1982: 120 Figs 2 , 3

Type.

CHINA. Guangxi: Tianyang County, Anning Gongshe, Anon. 262 (holotype: IBK![IBK00200113]). = Elatostema huanjiangense W.T.Wang & Y.G.Wei, 2007: 816. Syn. nov. Type: China. Guangxi: Huanjiang County, Mulun, Hongdong, 19 April 2006, Y.G. Wei 06128 (holotype: PE![02050267]). = Elatostema tetracephalum W.T.Wang, Y.G.Wei & F.Wen, 2012: 1100. Syn. nov. Type: China. Guizhou: Huangping County, in forest of earth mount, 20 March 2010, Y.G. Wei & F. Wen 1067 (holotype: PE!, isotype: IBK!).

Description.

Perennial herb, terrestrial, dioecious. Stem 50-250 × 2-3 mm, ascending or erect, simple or branched, glabrous. Stipule 2, persistent, 2-2.2 × 0.2 mm, lanceolate-linear, glabrous. Leaves distichous, alternate, sessile or short petiole; laminae 30-150 × 14-60 mm, length:width ratio 2.1-2.5:1, obliquely elliptic, papery; triplinerve or rarely semitriplinerve; abaxial surface glabrous, adaxial surface sparsely setulose; cystoliths densely scattered, bacilliform; base asymmetrical, broader-half rounded or auriculate, narrower-half cuneate; margin crenate; apex shortly acuminate or acuminate. Staminate and pistillate inflorescences not borne on the same stems. Staminate inflorescences paired, axillary, cymiferous, bearing ca. 30 flowers, ca. 10 mm in diam., peduncle 1.6 × 0.4 mm, subglabrous; bracts membranous, linear-lanceolate or lanceolate-linear, 1.2-2.5 × 0.3-1 mm, sparsely ciliate; staminate flower bud ovoid, flowers ca. 1.6 × 1 mm, glabrous, tepals 5, subapical appendage ca. 1 mm, corniculate. Pistillate inflorescences paired, axillary, capitate, bearing ca. 20 flowers, inflorescences with three types: (1) simple capitulum, 1.5 mm in diam., receptacle inconspicuous, bracts ca. 10; (2) composite capitulum, comprised by four 2-branched simple capitulum; (3) simple capitulum, receptacle discoid-oblong, 2-3 × 0.8-2 mm, weakly divided into two lobes, glabrous, subtended by marginal bracts; bracts numerous, triangular, ca. 0.5 × 0.2-0.3 mm, glabrous; bracteoles 2 per flower, subequal, 0.5-1 mm, linear, semitransparent; Pistillate flowers: ovary ovoid, ca. 0.6 mm; achene 6.122-7.99 × 3.891-5.119 mm, length:width ratio 1.56-1.57:1, broadly ellipsoid, with 4 longitudinal ribs and tuberculate, two opposite longitudinal ribs winged.

Additional specimen examined.

CHINA. Guangxi: Huanjiang County, Mulun nature reserve, Hongdong, 8 April 2009, Y.G. Wei g124 (IBK!, PE!); Huanjiang County, Mulun nature reserve, Leyi Village, Donglai, 3 May 2011, Y.S. Huang, Y.B. Liao & R.C. Peng y0216 (IBK!); Huanjiang County, Mulun nature reserve, Leyi Village, Donglai, 18 April 2012, W.B. Xu, R.C. Peng & R.C. Hu ML1037 (IBK!); Huanjiang County, Mulun nature reserve, Hongdong, 16 April 2012, L.F. Fu FL004 (IBK!, PE!); Huanjiang County, Chuanshan Town, on the way from Hongdong to Zhonglun, 9 May 2006, Man-Fu Hou 117 (PE!); Tianyang County, Babie Village, Anning Village, 6 June 2018, L.F. Fu, Y.C. Liu & W.J. Xu FLF180606-01 (IBK!); Guizhou: Huangping County, Feiyun gorge, 17 May 2012, Y.H. Tseng & L.F. Fu Zn1217 (IBK!), 8 Nov. 2015, A.K. Monro & L.F. Fu 7696 (IBK!, K!); Shibing County, Yun Tai Mountain, 10 Nov. 2015, A.K. Monro & L.F. Fu 7705 (IBK!, K!); Zhen Yuan County, Tiexi Tourist Park, 10 Nov. 2015, A.K. Monro & L.F. Fu 7719 (IBK!, K!).

Conservation status.

An Extinction Threat Assessment was undertaken using the IUCN methodology (2012). Elatostema setulosum is known from five localities in Guangxi (one population) and Guizhou (four populations), China. We estimate that the population of mature individuals is greater than 1000. The given surface area of a polygon including the known localities for this species is greater than 27,000 km2 ( Fig. 3 ); it is also likely that there remain as yet undiscovered populations. For these reasons we assess E. setulosum as Least Concern (LC).

Figures

Figure 2. Comparison of type specimens between Elatostema setulosum (A, C-E) and E. huanjiangense (B, F-H): A, B habit C, F stem D, G leaf pubescence E, H pistillate inflorescence.

Figure 3. Distribution map of Elatostema huanjiangense (circle), E. setulosum (star) and E. tetracephalum (triangle).