Carex ledongensis H.B. Yang & G.D. Liu, 2020

Yang, Hu-Biao & Liu, Guo-Dao, 2020, Carex ledongensis (Cyperaceae), a new sedge from Hainan Isl. Of South China, Phytotaxa 461 (2), pp. 72-78 : 72-74

Carex ledongensis H.B. Yang & G.D. Liu sp. nov. ( Figures 2–3 ).

Diagnosis:— The new species resembles superficially C. pseudotristachya , but differs from it by its leaves 4–5 times longer than culms (vs. equaling or slightly exceeding culms), spikes 3 (vs. 2–4), terminal spike with 1.5 cm long peduncle (vs. subsessile), lateral spikes

androgynous (vs. pistillate), perigynia fusiform (vs. ovate-fusiform), 6–8 mm long (vs. 4.5–5 mm long), and sessile (vs. stipitate), and nutlets brownish black (vs. yellowish), 5–6 mm long (vs. ca. 3 mm long) ( Fig. 2–3 ). See also Table 1 for more details in the comparison and additional characters.

Type: — CHINA. Hainan: Ledong County, Jianfeng Ling Nature Reserve , 1357 m, N 108°52’23”, E 18°43’1”, 25 April 2019, Yang Hubiao 201904254614 (holotype, IBSC; isotypes, ATCH) .

Rhizome short. Culms 10–20(–25) cm tall, trigonous, smooth. Basal sheaths dark brown, splitting into fibers. Leaves basal, much longer than culms; blades green, 50–100 long, 0.5–1 cm wide, glabrous on both surfaces, margins scabrid. Bracts sheathing, lowermost one leaf-like, to 30 cm long or more, longer than the inflorescence, upper 1 or 2 shortly leaf-like or bristle-like; sheaths ca. 5 mm long. Inflorescence racemose, with 3 spikes, upper 2 contiguous, lowermost 1 distant; terminal spike staminate, linear-cylindric, ca. 3 cm long, ca. 1 mm wide, base with 1.5 cm long peduncle; lateral spikes androgynous, 1–1.5 cm long, the upper part with ca. 5 staminate flowers, lower part with ca. 5 pistillate flowers, upper peduncles short and enclosed in bract sheath, lowest one ca. 4 cm long, exserted. Staminate glumes green, ovate-lanceolate, glabrous, ca. 5 mm, membranous, margin connate from base to middle, with a green 1-veined costa excurrent into a 1 mm long awn; pistillate glumes green, sparsely pubescent, ovate, ca. 4 mm, membranous, with 1 green midrib, margins hyaline, and apex obtuse. Perigynia green, deciduous after ripening, longer than pistillate glumes, erect, fusiform, trigonous, 6–8 mm, membranous, puberulent, many veined, base attenuate and sessile, apex attenuate into a beak, orifice minutely 2-toothed. Nutlets tightly enveloped, ovate, trigonous, 5–6 mm long, brownish black, base shortly stipitate, apex discoid-annulate; style base conically thickened. Stigmas 3.

Distribution and Habitat:— Carex ledongensis was collected in the Jianfengling Nature Reserve on Hainan Island. It grows under the tropical monsoon rainforest, at altitudes of 1357 m.Associates include Pentaphylax euryoides Gardn. et Champ. , Ternstroemia gymnanthera (Wight et Arn.) Beddome , Photinia glabra (Thunb.) Maxim. , Polyspora axillaris (Roxburgh ex Ker Gawler) Sweet , Rhodomyrtus tomentosa (Ait.) Hassk. , Manglietia hainanensis Dandy , Oligostachyum nuspiculum (McClure) Wang et Ye.

Phenology:—Flowers have been observed from March. The plant bears ripe fruits in May.

Etymology:—The epithet “ ledongensis ” refers to from the type locality, Ledong county in Hainan island. Accordingly the plant is called “ 乐东Îv ” in Chinese.

Conservation status:—The population of Carex ledongensis covers an area of about 30 000 m 2. But the individual density of population is not high, with about 25 caespitose individuals per 100 m 2. This population needs to be monitored for its conservation.

Figures

FIGURE 2. Carex ledongensis, A. Habit, B. Inflorescence, C. Lateral bisexual spike, D. Terminal staminate spike, E. Periginia, F. Nutlet, G. Staminate glume, H. Pistillate glume, J. Stigma, K. Nutlet(SEM), L. Surface sculpturing of Nutlet(SEM); C. pseudotristachya, M. Nutlet(SEM), N.Surface sculpturing of Nutlet(SEM).

FIGURE 3. Carex ledongensis, A. Habit, B. Inflorescence, C. Terminal staminate spike, D. Lateral bisexual spike, E. Staminate glume, F. Pistillate glume, G. Periginia, H. Nutlet. Drawn by Yu-xi Zhu.