Cephalanthus glabrifolius Hayata (Hayata 1920: 51)

Romero, Maria Florencia, Gonzalez, Ana Maria & Salas, Roberto Manuel, 2023, Sylvainia, a new monospecific genus within the subtribe Cephalanthinae (Rubiaceae, Naucleeae), Plant Ecology and Evolution 156 (1), pp. 85-111 : 85

3. Cephalanthus glabrifolius Hayata (Hayata 1920: 51)

Figs 3 , 6

Type.

TAIWAN • Koteisho [古亭庄]; 19 Jun. 1905; s.col. 532; holotype: TI [TI00080001] .

Description.

Shrub 3-5 m tall, much-branched. Leaves opposite, pseudopetiolate; pseudopetioles subcylindrical, glabrous, 5-8 mm long; blades ovate or elliptic, glabrous, base acute or rounded, apex acute or acuminate, subcoriaceous or papyraceous, discolorous, 6.5-10 × 2.3-4.5 cm; principal lateral veins 6-9 on each side, glabrous or sparsely pilose, slightly discolorous, leaf domatia absent; stipules ovate, apex acuminate, dark colleters present at the apex and margins, light colleters dispersed on the ventral (inner) side, intermingled with numerous trichomes. Inflorescences pedunculate, peduncles 2-6 cm long, glabrous; bracteate, bracts foliaceous, bracteoles spatulate, pubescent, with dark colleters present at the interlobular sinuses and apex. Flowers perfect; calyx 5-lobed, hypanthium pubescent, obovate, 1.6-1.8 mm long, lobes broadly triangular, pubescent on both sides, 0.2-0.35 mm long, margin pubescent, dark colleters at the interlobular sinuses and apex; corolla hypocrateriform, 5-lobed, 7-8 mm long, lobes ovate or subtriangular, 1.5-2 mm long, externally pubescent, internally with a fringe of sparse hairs from the apex of lobes to the upper third of the tube, with dark colleters at the interlobular sinuses, tube glabrous externally; stamens 5, filaments filiform; style filiform, 8-10 mm long; stigma capitate and exserted at flower maturity. Fruits obpyramidal, glabrous, 4.5-5 mm long. Seeds with an almost smooth surface, 2.5-2.8 mm long; with a large aril 1.5-2 mm long.

Distribution.

Cephalanthus glabrifolius has been reported from southeast China, east India, Myanmar, Taiwan, and Vietnam (Fig. 3 ).

Phenology.

Flowers from November to April and bears fruit from March to August.

Habitat and ecology.

Occurs along streams and near lakes from sea level up to 1800 m. Occasionally growing on roadsides.

Additional material examined.

CHINA • 1856; Fortune 1545; P [P05458899]. - Guangdong • Kwangtung, Hau T’ong Shan , Fuk Lung Monastery , Sin-fung District ; 1-19 Jun. 1938; Taam 861 ; US [ US 02370626] • Kwangtung, Sha Lo Shan, Lo-Lo-ha Village , Sin-fung District ; 6-25 Jul. 1938; Taam 1016 ; US, P [P05458901] • Kwangtung, near Fung Wan, North River Region ; 14 Jul. 1924; Canton Christian College 12856 ; US [ US 02370639]. - Guangxi • Kwangsi, Bui Tung, NU bai, Border of Kweichow ; 1158 m; 27 Apr. 1928; Ching 6258 ; US [ US 02370631]. - Hainan • 1889; Henry 8013; P [P05458905]. - Hunan • I-Chia-Ao, Changning Hsien ; 3 Jul. 1935; Fan & Li 141; P [P05458902], L [L.2853483]. - Jiangxi • Kiangsi, Oo Chi Shan, near Lam Uk Village , Lungnan district ; 1-25 Oct. 1934; Lau 4608 ; US [ US 02370636]. - Zhejiang • Southern Chekiang, Between Ping Yung and Tai Shan , 5 km, W. of Tai Suan, S. Chekiang; 579 m; 3 Aug. 1924; Ching 2222 ; US [ US 02370638] • Western Chekiang, Region, 130 km W. of Wenchow ; 900 ft; 7 Jun. 1924; Ching 1852 ; US [ US 02370637].

INDIA - Nagaland • Naga Hills ; 13 Sep. 1924; Jagarmani 497 ; US [ US 02370630].

LAOS - Vientiane • Ban Sa Phan Mo ; 2 Apr. 1950; Vidal 1198; P [P03820113] . - Xiangkhouang • Plaine des Jarres ; vers 1100 m; May 1931; Colami 4535; P [P03820116] .

MYANMAR • Lieut & Toppin 2667; E [E00847463] • Birma and Malay Peninsula; 1835-1845; Griffith 3090 [Herbarium of the late East India Company , Herb. Griffith]; NY [2651078]. - Sagaing • Katha [city]; 28 Mar. 1912; Lace 5719; E [E00847465, E00847464] .

TAIWAN - Taipei • 19 Jun. 1962; Chao 1065; HAST • Taipei City, at Academia Sinica campus (中研院院區), at pond border; 25°2 ’30” N, 121°36 ’47” E; 20 m ; 8 Feb. 2013; Huang 6640; HAST • [City of] Taihoku ; 2 Jun. 1929; Sasaki-Syun’iti s.n.; L [L.2853197, L.2853198], TAI. - Ilan Hsien • Ayushan (阿玉山); 24°46 ’60” N, 121°35 ’60” E ; 10 Jul. 1996; Cheng s.n.; HAST [HAST-79561], TAIF • Tungshan Hsiang, Tungshan (冬山), in 平地水溝邊 [habitat] ; 10 Jul. 1998; Li 595; HAST • Wuchieh Hsiang, Hsiaowei-Tapu (孝威-大埔), at roadside; 24°41 ’13” N, 121°48 ’25” E; 2-4 m; 12 Aug. 1995; Wang & Lin 1496; HAST • Wushiherhchia (五十二甲), on paddy ridges; 24°39 ’5” N, 121°48 ’17” E; 5 m; 9 Jul. 1998; Kao & Huang 575; HAST.

VIETNAM - Bắc Giang • Province de Bac Giáng, bord d’une petite mare; 31 May 1936; Pételot 5674; P [P03820111]. - Hòa Bình • Route de Hansi à Hoa Binh; Mar. 1933; Pételot s.n.; P [P03820114, P03820115] • “Indochine”; 18-19 Apr. 1914; Chevalier s.n.; P [P03820070] • "French Indochina", Environs de Murang Chon , Province de Hva Binh; Mar. 1933; Bonkin s.n. ; US [ US 02370641] • "Tonkin Occidental " [N Vietnam], in paludib.; 30 Apr. 1884; Bon s.n. .; P [P03820095] • In nemore Ván Xa; 4 May 1886; Bon 3139; P [P03820096]. - Phú Thọ • Tonkin, prov. de Phú Tho, reserve for Cham Wong ; 8 Sep. 1916; Chevalier 3213; P [P3820101] • Réserve forestière de Chan-Mong; 16-17 Apr. 1914; Fleury 32135; P [P05459514, P05459515]. - Hanói • Phan Đình Giót, sur le bord des marais; 2 Jul. 1889; Balansa 2679; P [P03820109] .

Notes.

Cephalanthus glabrifolius was described by Bunzó Hayata in 1920. The species was synonymized under C. tetrandrus by Ridsdale (1976) without analysis of the type specimen. Despite his exhaustive review, some morphological characters were underestimated, e.g. presence or absence of domatia, and floral features (shape of hypanthium, size and shape of calyx lobes, shape and indumentum of corolla lobes, and internal and external indumentum of corolla tube). Particularly, the pattern of the distribution of hairs inside of the corolla was not addressed in detail. For a summary of the differences between C. glabrifolius and C. tetrandrus see Table 2 and the key to the species of Cephalanthus . Based on our study, we consider C. glabrifolius as a valid species.

Figures

Figure 3. Distribution map of Cephalanthus angustifolius, C. glabrifolius, and C. tetrandrus.

Figure 6. Cephalanthus glabrifolius. A. Flowering branch. B. Flower. C. Unfolded corolla. D. Hypanthium, style, and stigma. E. Longitudinal section through the hypanthium. F. Stamen. G. Dorsal view of schizocarp. H. Ventral view of the mericarp. I. Longitudinal section through the schizocarp. J. Dorsal view of seed with aril. K. Subventral view of seed with aril. L. Lateral view of seed with aril. Drawn by Laura Simon.