Cephalanthus tetrandrus (Roxb.) Ridsdale & Bakh.f. (Ridsdale and Bakhuizen in Ridsdale 1976: 182)

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

6. Cephalanthus tetrandrus (Roxb.) Ridsdale & Bakh.f. (Ridsdale and Bakhuizen in Ridsdale 1976: 182)

Figs 3 , 10

Nauclea tetrandra Roxb. ( Roxburgh 1824: 125) - Type: same as for Cephalanthus tetrandrus .

Cephalanthus ratoensis Hayata ( Hayata 1920: 52) - Type: TAIWAN • Girancho; 1904; Kawakami 34; holotype: TI [TI00080002].

Type.

INDIA - Meghalaya • Khasia, M. Sillet; 1832; F. da Silva s.n. in Wallich Cat. 6101A; first-step lectotype (designated by Ridsdale 1976): K; second-step lectotype (designated here): K [K001067160]; isolectotypes: BR [BR0000005585892], K [K001123031], K [K001123032], P [P03820092]; syntypes : INDIA • [Assam]; s.col. s.n.; K [K000265514] • s.col. s.n.; K [K000265513] • s.col. s.n.; K [K000265509] • Goalpara ; 14 Apr. 1814; F. da Silva s.n. in Wallich Cat. 6101B • [Uttar Pradesh], “Goruckpore” [Gorakhpur]; 11 May 1808; F. da Silva s.n. in Wallich Cat. 6101C; K [K001123034] .

Description.

Shrub 3-6 m tall, much-branched. Stems pubescent or puberulous, sparsely cover by lenticels. Leaves opposite, pseudopetiolate; pseudopetioles subcylindrical, glabrous or puberulous, 9-13 mm long; blades ovate or elliptic, puberulous or pubescent on both sides, or glabrous above and pubescent beneath, base rounded or subcordate, apex acute, subcoriaceous, discolorous, 7-10 × 3-5 cm; principal lateral veins 6-9 on each side, slightly discolorous, leaf domatia present as tufts of hair; stipules ovate, tardily deciduous, with dark colleters at the apex and margins, light colleters on the ventral (inner) side, intermingled with numerous trichomes. Inflorescences pedunculate; peduncle 2-6 cm long, densely pubescent, bracts foliaceous, with dark colleters at the apex and margins; bracteoles spatulate, densely pubescent, dark colleters on the apex. Flowers perfect; calyx 4- or 5-lobed, hypanthium cupuliform, glabrous or glabrescent externally, 1.3-2 mm long; lobes broadly ovate, apex obtuse, internally pubescent, glabrous externally, margin puberulous, 0.7-1 mm long, dark colleters present at the interlobular sinuses; corolla hypocrateriform, 4- or 5-lobed, 5-9 mm long, lobes oblong, obtuse, 1-1.3 mm long, internally glabrous, dark colleters present at the interlobular sinuses, tube internally with a fringe of hairs from the insertion of the stamens to the base, externally glabrous; stamens 4 or 5, filaments filiform, glabrous, ca 0.3 mm long; style filiform, 8-13 mm long; stigma capitate and exserted at flower maturity. Fruits obpyramidal or turbinate, glabrous, 4-6 mm long. Seeds 1.3-2 mm long; aril 1.6-1.9 mm long.

Distribution.

The species grows in Bangladesh, China (Guangdong, Hainan, and Yunnan), Hong Kong, India (Assam, East Bengal, and Meghalaya), Laos, Taiwan, Thailand, and Vietnam (Fig. 3 ).

Habitat and ecology.

This species is typically associated with temporarily waterlogged areas, such as riverbanks, lakes, and lagoons. It forms especially dense populations in large lagoons. Mikhama and Sirisant (2016) considered the large populations of C. tetrandrus growing in lagoons as freshwater swamp forest (temporary inundated forest). Mikhama and Sirisant (2016) have studied natural populations in the north of Thailand (Nakhon Phanom province) and showed the important socio-cultural role and farming support for villagers that live in close proximity to these particular habitats. According to them, this interaction explains the good state of preservation of this species (at least locally) and its habitat. These waterbodies are the main source of water supply (for human consumption) and are also relevant in the water management for off-season rice farming.

Phenology.

The species flowers from August to January and bears fruit from January to May.

Vernacular name.

Kai chi muk (cock spur tree), Mak Tang Noi (Spire 327 (P)); Chai-wan (Kanlaya Mikhama, Nakhon Phanom University, Thailand, pers. comm.).

Additional material examined.

CHINA • Habitat in provincia Cantoniensis Sinarum; Loureiro 67-1; P [P00150877]; wrongly cited as the holotype of C. montanus because it does not correspond with the protologue • Sep. 1845 -1847; Fortune 15; P [P05458904] • Sep. 1845 -1847; Fortune 15b; P [P05458910]. - Guangdong • Wan Tong Shan , ( Ying Tak District ); 6-24 Jun. 1932; Tsui 325; P [P05458909] , US [ US 02370625] • Yang Shan and Vecinity, South of Linchow; 20 Oct. 1938; Tsui 615; P [P03820074] • Lung T’au Shan, along riverbank; 14 Jul. 1924; Fungwanhui [To and Ts’ang] 12856; P [P03820076]. - Hainan • Fung Muk Shan, (Taam Chau District), Sz Kai Taai Shue; 3 May 1928; Tsang 210; MO • Hainan Woh Ham Shi and Vicinity, Lam Ko District , Ma Yin Shu; 22 Apr. 1933; Lei 576; L [L.2853487], P [P05458903] , US [ US 02370635]. - Yunnan • Du Yunnan, Arbres Kiao Kia [Qiaojia]; 400 m; Nov. 1910; Maire 6392 ; US [ US 02370640, US 02369505].

HONG KONG • Lar Tai Shie, jardin de Hong-Kong; 1 May 1893; s.col. 396; P [P05458906] .

INDIA • Roxburg s.n.; P [P03820106] • "Indes Orientalis"; 1859; Hooker s.n.; P [P03820102]. - Assam • “Nayaltia”; May 1902; Chatterjee s.n.; MPU [MPU1100692], P [P03820087] • Assam; Jenkins s.n.; P [P03820091], L [L.2853486] • Jenkins s.n.; P [P03820088]. - [Bengal] • East Bengal ; Griffth 3090/1; K, P [P03820093] • Hortus suburbanus Calcuttensis, Bot. Gardens of Calcutta and Serampore; 1834-1841; Voigt 229; C, P [P05458908]. - Meghalaya • Shillong; May 1894; King s.n.; P [P03820085] • Phulbari, Garo Hills, near sea level, bush in swamp; 15 Apr. 1950; Koelz 25085; L [L.2853485] .

LAOS • “Indo-Chine”; Dec. 1903; Spire 327; P [P3820103] • "Expedition du Me-Kong", Sainyabuli; 1866-1868; Thorel 9199; P [P03820099, P03820100] • "Mekong Sani", sur argile; 1080 m; May 1932; Pételot 4455; P [P03820110] .

TAIWAN • Tomita-cho ; 15 Dec. 1933; Tanaka & Shimada 13600; L [L.2853488, L.2853484], P [P05458900] • Taipeh; 6 Oct. 1897; Yano 36; LE .

THAILAND • “Siam”; Jan. 1924; Kerr 8337; TCD [TCD0017286] .

VIETNAM • [North Vietnam], Tonkin Occidental, Khang Chúóng; 26 May 1882; Bon s.n..; P [P03820083, P05458911] • Khang Chúóng, ad oras aquarum; 26 May 1882; Bon 1593bis; P [P03820090] • “Tonkin”; 1909; d’Alleizette 219; P [P03820105, P03820094]. - Hải Phòng • Tonkin, dans les facies; 15 Jan. 1886; Balansa 637; P. - Hanói • Pagode de Balny , près de Hanoï, bord des marais; Apr. 1891; Balansa 4802; P [P03820072]. - Thừa Thiên-Hu ế • 14 Apr. 1910; Bauche 72; P [P03820098] • 16 Apr. 1910; Bauche 33; P [P03820107] .

Notes.

Roxburgh (1824) described Nauclea tetrandra based on specimens deposited at the Kew herbarium and belonging to Wallich’s catalogue ( Stafleu and Cowan 1983; Wallich 1834). According to Charles Baron Clarke’s notes on the “Khasia” localities of Wallich’s catalogue, places labelled as "M. Sillet" belong to Meghalaya State (notes posthumously published in an anonymous text, Anonymous 1913). According to our observations, at the Kew herbarium, there are several specimens that can be considered as part of the original materials of Nauclea tetrandra (see type section). Ridsdale (1976) made the combination Cephalanthus tetrandrus (as " tetrandra ") mentioning as type material " Wallich Cat. 6101A " deposited in K; an action that is here considered an inadvertent lectotypification. However, in the Kew herbarium, there are duplicates of the same collections of F.A. Silva listed as belonging to Wallich’s catalogue and also identified as " Wallich Cat. 6101A ". Duplicates of this collection can be found in the BR and P herbaria. Thus, a second-step lectotype must be designated following Turland et al. (2018: article 9.17).

Figures

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

Figure 10. Cephalanthus tetrandrus. A. Flowering branch. B. Axil of the middle and secondary vein showing domatia as tuft of hairs. C. Perfect flower. D. Unfolded corolla. E. Side view of schizocarp. F. Ventral view of mericarp. G. Ventral view of schizocarp. H. Dorsal view of seed with aril. I. Subventral view of seed with aril. Drawn by Laura Simon.