Carex concava H.B. Yang, X.X. Li & G.D. Liu, 2016

Yang, Hu-Biao, Li, Xiao-Xia, Bai, Chang-Jun, Wang, Wen-Qiang & Liu, Guo-Dao, 2016, Carex concava (Carex sect. Rhomboidales, Cyperaceae), a new species from Hainan, China, Phytotaxa 283 (2), pp. 155-162 : 156-160

Carex concava H.B. Yang, X.X. Li & G.D. Liu sp. nov. ( Figs 1–3 )

Diagnosis:—The new species is similar to C. paracheniana , but differs in having more wider blades and longer sheaths of bracts, inflorescence with 3 spikes; terminal spike 2–6 cm long and with a 4–14 cm long peduncle, lateral spikes 3–6 cm long, loosely flowered and with 8–15 cm long peduncles; staminate glume ovate, 1-veined costa excurrent into a shortly awn ca. 0.3 mm; Pistillate glume ovate, ca. 4 mm long, 1-veined costa excurrent into a awn ca. 1 mm; Perigynia fusiform and green; nutlets inclined-oval, brownish black, with 3 angles deeply constricted at the middle and the adaxial side deeply concave below the constriction.

Type:— CHINA. Hainan: Wuzhi Shan County, Wuzhi Shan Nature Reserve , under forest, alt. 1200–1500 m, 10 April 2014, Yang Hubiao 20140410002 (holotype, IBSC; isotype, TCGRI) .

Herbs perennial. Rhizome short, ligneous, covered with dark brown fibrous remains of old leaf sheaths. Culms central, 20–45 × ca. 0.2 cm, trigonous. Leaves basal, longer than culms, with ca. 5 cm long sheaths at base; blades green, 5–75 × 0.5–1 cm, glabrous on both surfaces, acuminate at apex. Involucral bracts shortly, leafy, 15–23 × ca. 0.3 cm, sheathed; sheaths ca. 5 cm long. Inflorescence paniculate, with 3 spikes; terminal spike staminate, linear-cylindrical, 2–6 × ca. 0.2 cm, with a peduncle 4–14 cm long; lateral spikes pistillate, linear-cylindrical, 3–6 × ca. 0.5 cm, loosely flowered, pedunculate; peduncles exserted from sheaths, 8–15 cm long. Staminate glumes ovate, ca. 4 × 2 mm, membranous, glabrous, obtuse at apex, with a green 1-veined costa excurrent into a shortly awn ca. 0.3 mm. Pistillate glumes ovate, yellowish white, ca. 4 × ca. 2 mm, membranous, obtuse at apex, with a green 1-veined costa excurrent into a awn ca. 1 mm. Perigynia fusiform, ca. 7 mm long, slightly longer than pistillate glume, obtusely trigonous, sparsely pubescent on upper veins, distinctly veined, apex gradually contracted into shortly beak, beak sparsely pubescent on veins. Nutlets tightly enveloped, rhombic-oval, trigonous, ca. 4 × ca. 2 mm, brownish black, with 3 angles deeply constricted at the middle, the adaxial side deeply concave below the constriction, apex abruptly contracted into a cylindrical, slightly curved short beak, expanding into an annulate orifice; style-base persistent, thickened.

Distribution and habitat:— Carex concava was collected from Wuzhi Shan Nature Reserve, Hainan, China. It grows under the tropical mountain rain forest at altitudes of 1200–1500 m. Associates include Podocarpus imbricatus Blume , Dacrydium pierrei Hickel , Altingia obovata Merr. & Chun , Xanthophyllum hainanense Hu , Daphniphyllum paxianum K.Rosenthal , Daemonorops margaritae (Hance) Becc. , Calamus tetradactylus Hance , Licuala fordiana Becc. , Millettia pachyloba Drake , Manglietia hainanensis Dandy , Carex tsoi Merrill et Chun , C. planiscapa Chun et F.C.How. and C. breviscapa C.B. Clarke.

Phenology:—Flowering occurs from March and usually nutlets mature from April to June.

Etymology:—The epithet “ concava ” refers to the nutlets, which are deeply constricted at the middle and the side toward of spike-stalk deeply concave at base.

Relationships:—The new species belongs to Carex sect. Rhomboidales . In Hainan Island, five species, C. harlandii Boott ( Boott 1860), C. saxicola Tang & F.T. Wang ( Tang & Wang 1977), C. longipetiolata Q.L. Wang, H.B. Yang & Y.F. Deng ( Wang et al. 2012), C. procumbens H.B. Yang, X.X. Li & G.D. Liu ( Yang et al. 2015a), and C. jianfengensis H.B. Yang, X.X. Li & G.D. Liu ( Yang et al. 2015b) have been reported. Besides, five new taxa from other regions have recently been described in sect. Rhomboidales : C. jubozanensis J. Oda & A. Tanaka ( Oda et al. 2003), C. austrozhejiangensis C.Z. Zheng & X.F. Jin ( Jin et al. 2004), C. kagoshimensis Tak. Shimizu ( Shimizu 2008), C. yandangshanica C.Z. Zheng & X.F. Jin ( Jin et al. 2010) and C. paracheniana X.F. Jin, D.A. Simpson & C.Z. Zheng ( Jin et al. 2012b). However, C. concava can be easily distinguished from all the species mentioned above by its nutlets with 3 angles deeply constricted at the middle, the side toward of spike-stalk deeply concave at base. It is similar to C. paracheniana based on the shape of nutlets and perigynia, but differences are clear as mentioned in Table 1. Futhermore, based on SEM observations, this new species has no protruding central silica bodies in epidermal cells ( Fig 2 ). Carex paracheniana displays protruding, irregularly 5-6-gonal, central silica bodies in epiderminal cells ( Jin & Zheng 2013).

Additional specimens examined (Paratypes):— CHINA. Hainan: Wuzhi Shan County, Wuzhi Shan Nature

Reserve, under forest, alt. 1200 m, 17 April 2014, Yang Hubiao 20140417008 (four paratypes, TCGRI).

Figures

FIGURE 1. Carex concava, A. Inflorescence. B. Habit. C. Lateral pistillate spike. D. Terminal staminate spike. E. Perigynium with stigmas. F. Pistillate glume. G. Staminate glume. Scale A, B, D bars=1 cm; E, F, G bars=1 mm. Photographs by Hu-Biao YANG (Apr. 15th, 2014).

FIGURE 2. Carex concava, A. Perigynium. B. Nutlet. C. Perigynium, distinctly veined (SEM). D. Perigynium (SEM). E. Nutlet (SEM). F. Epidermal cells (SEM). (Scale bars A, B, D, E=1 mm; C=500 um; F=200 um). Photographs by Hu-Biao YANG (Apr. 15th, 2014 and Oct. 10th, 2014).

FIGURE 3. Carex concava. A. Habit. B. Terminal staminate spike. C. Lateral pistillate spike. D. Staminate glume. E. Pistillate glume. F. Perigynium. G. Nutlet. Drawn by Yu-xi Zhu.