Description from Flora of China
Lianas or scandent shrubs, unarmed. Raphides absent. Leaves opposite, sometimes with domatia; stipules caducous, interpetiolar, triangular. Inflorescences axillary [to terminal], 1-flowered [or cymose and several to many flowered], pedunculate, bracteate. Flowers sessile, pedunculate, or pedicellate, bisexual, monomorphic. Calyx limb 5-lobed. Corolla pale yellow or white becoming yellowed with age, salverform, variously glabrous or pubescent inside; lobes 5, convolute to right in bud. Stamens 5, inserted in corolla throat, exserted; filaments short; anthers basifixed. Ovary 2-celled, ovules numerous in each cell on axile placentas; stigma fusiform, exserted. Fruit capsular, subglobose, loculicidally dehiscent with valves sometimes secondarily separating along septum, woody, with calyx limb persistent; seeds several, medium-sized to large, flattened, suborbicular, bordered by a regularly erose wing; endosperm fleshy; embryo straight; cotyledons short; radicle terete, basiscopic.
The 3-5-porate pollen of Coptosapelta was studied by Verellen et al. (J. Pl. Res. 117: 57-68. 2003), who also noted that the genus has secondary pollen presentation and accumulates aluminum in the leaves. Based on molecular and some morphological characters, Coptosapelta is now considered rather isolated and one of the most basal lineages in Rubiaceae (Bremer et al., Syst. Biol. 48: 413-435. 1999; Bremer & Manen, Pl. Syst. Evol. 225: 43-72. 2000), with its closest relative probably being Acranthera and these two genera most closely related to Luculia (Rydin et al., Pl. Syst. Evol. 278: 101-123. 2009).
Sixteen species: China, Indonesia, Japan, Laos, Malaysia, Myanmar, New Guinea, Philippines, Thailand, Vietnam; one species in China.
(Authors: Chen Tao (陈涛); Charlotte M. Taylor)