Carex paracheniana X. F. Jin, D. A. Simpson & C. Z. Zheng, 2012

Jin, Xiao-Feng, Simpson, David A., Zheng, Chao-Zong, Sun, Li & Zhang, Hong-Wei, 2012, Carex paracheniana (Carex sect. Rhomboidales, Cyperaceae), a New Species from Guangxi and Guizhou, China, Systematic Botany (Basel, Switzerland) 37 (4), pp. 929-937 : 931-936

Carex paracheniana X. F. Jin, D. A. Simpson & C. Z. Zheng , sp. nov. —TYPE: CHINA. Guangxi Zhuangzu Autonomous Region: Lingui County, Wantian Township , Baishi Village , roadside on slope, 110 04 0 33.86 00 (E), 25 39 0 13.26 00 (N), alt. 800 m, 22 Apr 2004 (fl., fr.), X. F. Jin 947 (holotype: HTC!; isotypes: HZU!, ZM!).

Herbaceous perennial. Rhizome brownish-black, woody, thick, short, with many yellowish-brown, fibrous adventitious roots. Culms caespitose, central, 8–35 cm tall, trigonous, smooth, covered with purplish-brown fibrous sheaths at base. Leaves longer or equal to culms; leaf-blade 3–5 mm wide, flat, smooth on lower half, scabrous on upper margins; sheaths brown, fibriform at apex. Involucral bracts leaf-like, shorter than inflorescence, sheathed; sheaths 0.5–1.5 cm long, obliquely truncate at orifice. Inflorescence paniculate, with 3–4 spikes; terminal spike staminate, cylindrical or clavate, yellowish-brown, 2–3 cm long, 2–2.5 mm wide, with a 2.5–4 cm long scabrous peduncle at base; lateral spikes pistillate, bearing a few staminate flowers at apex, cylindrical, 1–3 cm long, 7–9 mm wide, densely flowered, pedunculate; peduncles 1.5–3 cm long, slightly exserted from sheaths. Staminate scales ovate-oblong, pale brown, membranous, 4–4.5 mm long, 1.5–1.8 mm wide, obtuse at apex, green 3-veined costa on dorsal surface. Pistillate scales ovate-elliptic, 6.5–7 mm long (including awn), ca. 1.5 mm wide, glaucous or pale yellow, acuminate at apex, green 3-veined costa excurrent into a ca. 2 mm long scabrous awn. Perigynia broadly ovoid (excluding beak), 7–7.5 mm long, slightly longer than pistillate scales (including beak), ca. 3 mm wide, obliquely patent, obtusely trigonous, herbaceous, brownish-green, distinctly veined, sparsely pubescent on upper veins, abruptly contracted into a ca. 2 mm long beak at apex; beak sparsely pubescent at margin, orifice 2-lobed with short teeth. Stigmas 3; style thickened at base. Nutlets tightly enveloped by the perigynia, rhombic-ovoid, trigonous, 4.5–5 mm long (including beak), 2–2.5 mm wide, castaneous, with 3 angles constricted at middle, sides concave above and below, shortly curved, stipitate at base, abruptly contracted into a ca. 1 mm long cylindrical beak at apex, beak slightly curved, slightly annulate at orifice. Figure 5 : B, C and Figure 6 .

Representative Specimens Examined— CHINA. Guangxi Zhuangzu Autonomous Region: Lingui County, Wantian Township , Baishi Village , on slope, alt. 1,000 m, 22 Apr 2004, X. F. Jin 943 ( PE) ; the same locality, under forest, alt. 550 m, 14 May 2009, X. F. Jin 2379 ( HTC, ZM), 2380 ( HTC, HZU). Guizhou: Pingba County, Chaotian, on slope, alt. 1,440 m, 11 Apr 1987, Pingba Exped. 380 ( GZTM) .

Distribution and Habitat— Carex paracheniana is only known from two localities in southern China ( Fig. 7 ). It grows in moist places under evergreen broad-leaved forest at 500–1,000 m ( Fig. 5 : A).

Phenology— Flowering and fruiting April-May.

Etymology— The specific epithet alludes to the morphological similarity of the new species to C. cheniana Tang & F. T. Wang ex S. Yun Liang.

Comments— The circumscription of sect. Rhomboidales by Ohwi (1936) excluded species with oblique beak orifices on the perigynia. Carex matsumurae was included in the section by Koyama (1962), Katsuyama (2005), and Hoshino and Masaki (2011), although it has perigynium beaks notched at the orifice, plano-convex nutlets, and two stigmas. These characters are different from those of other members of sect. Rhomboidales. Chang and Yang (1976) placed related species from northeastern China in two sections. The species with erect pistillate spikes and pubescent perigynia were placed in sect. Rhomboidales, while those with pendulous pistillate spikes and glabrous perigynia were placed in sect. Laxiflorae Kunth ex Mackenzie. Dai et al. (2000) also considered these two sections to identify the Chinese species of sect. Rhomboidales, but the name of sect. Laxiflorae was replaced by sect. Careyanae ( Jin et al. 2011). Based on all species of sect. Rhomboidales in China and Japan, as well as by considering the characters of leaf anatomy, epidermis, perigynium and nutlet, we emend the circumscription of sect. Rhomboidales as follows:

Culms lateral or central; terminal spike staminate, lateral spikes androgynous, usually with a long or short staminate part at apex, or pistillate. Perigynia ovoid to broadly ovoid, trigonous, glabrous or pubescent, tenuously venose, apex contracted into a long beak, beak orifice bifid. Stigmas 3; style thickened or not at base. Nutlets rhombic-ovoid, rarely obovoid or broadly obovoid, trigonous, constricted at middle angles, rarely not constricted, with a conspicuous beak or disc-annulate at apex, beak erect, slight curved or coiled.

Carex paracheniana is easily recognized as a member of sect. Rhomboidales, not only for the perigynium characters, but also for the nutlet morphology. It is similar to C. cheniana in having pale green leaves, and pistillate scales that are glaucous or pale yellow, long awned at the apex, but it differs in having 3–5 mm wide leaves, staminate scales that are obtuse at the apex, and nutlets contracted into a ca. 1 mm long, slightly curved beak at the apex. The new species also closely resembles C. brevicuspis , but differs by having ovate-elliptic pistillate scales that are glaucous or pale yellow, and long-awned at apex and by styles that are thickened at base. Characters distinguishing the new species from related taxa are summarized in Table 2 and the key.

Figures

FIG. 5. Photographs of Carex paracheniana. A. Natural habitat of the forest beside Baishi Village, Wantian Township, Lingui County, Guangxi Zhuangzhu Autonomous Region, China. B. Habit. C. Spikes, terminal one staminate and lateral pistillate. Scale bar = 2 cm in Fig. 5B, 1 cm in Fig. 5C.

FIG. 6. Carex paracheniana X. F. Jin, D. A. Simpson & C. Z. Zheng, sp. nov. A. Habit. B. Transverse section of culm. C. Staminate scale. D. Pistillate scale. E. Perigynium. F. Nutlet. All from X. F. Jin 947.

FIG. 7. Geographical distribution of Carex paracheniana X. F. Jin, D. A. Simpson & C. Z. Zheng in Guangxi and Guizhou, southern China.