Codonoboea

Full name and orig. publication: Codonoboea Ridl., Fl. Malay Pen. 2: 533 (1923).

Etymology: Composed of the Greek κωδων, kōdōn = bell, and the generic name Boea.

Synonyms: Didymocarpus sect. Codonoboea (Ridl.) Kiew (1990) and – with the exception of sect. Elati Ridl. (1905) – all sections established in Didymocarpus (Clarke 1883, Ridley 1896, 1905, 1907, 1923, Kiew 1995), Henckelia sect. Didymanthus (C.B.Clarke) A.Weber & B.L.Burtt, H. sect. Glossadenia A.Weber & B.L.Burtt (1998), H. sect. Heteroboea (Benth,) A.Weber & B.L.Burtt, H. sect. Didymanthus (C.B.Clarke) A.Weber & B.L.Burtt, Paraboea sect. Campanulatae Ridl. (1905), Platyadenia B.L.Burtt (1971). For a detailed synonymy list see Middleton et al. (2013).

Description (from Kiew & Lim 2011: 255): Perennial herbs with continuous growth. Stems usually woody, erect and either caulescent with an unbranched or branched stem to c. 50 cm tall or short and forming a rosette, or creeping. Leaves usually opposite, sometimes alternate to spiral, sessile or petiolate. Inflorescences axillary, with 1 or several per axil, sometimes epiphyllous; pedunculate pair-flowered cymes with 3-4 flowers or reduced to a single flower or branched, paniculate and many-flowered; bracteoles usually small, sometimes absent or large and conspicuous. Flowers 5-merous, with a small calyx divided almost to base; corolla tubular with 5 lobes, the lower 3 lobes often longer, large and trumpetshaped to narrowly tubular to campanulate to short-tubed and flat-faced; tube often pale purple, cream-coloured or white with concolourous lobes or with lobes deeply coloured and contrasting, less commonly red or yellow; frequently with a pair of yellow or orange-brown nectar guides, rarely with additional stripes or spots; stamens 2, filaments long or short with the anthers positioned in the mouth of the corolla, anthers coherent, connectives often with a tooth-like appendage; nectary forming a deep or shallow ring, sometimes with a lobed rim or short on the adaxial side or it does not surround the ovary base and is tongue-like or is lacking; ovary cylindric, tapering into the style, stigma either peltate or rounded (but never bilobed or lamellate). Capsules plagiocarpic, splitting adaxially, long, cylindric, 1-5 cm long, usually slender, rarely curved and slightly thicker towards the base.

Infrafamilial position: Didymocarpoideae-Trichosporeae-Didymocarpinae (Weber et al. 2013).

Chromosome number: x = 9, 2n = 18 (most species), 2n = 36 (C. hispida and allies, Kiehn et al. 1998).

Species number: Around 150.

Species names (only given in case of few species).

Type species: Codonoboea leucocodon (Ridl.) Ridl. (= Paraboea leucocodon Ridl.) (lecto Ivanina 1967).

Distribution: Sumatra, S Thailand, Peninsular Malaysia (c. 2/3 of the species), Singapore, Borneo, Philippines (Palawan), Sulawesi, New Guinea.

Ecology: Plants of rain forests, growing usually in humid places and deep shade; often found on banks of streams, sometimes rheophytic, or on shady, moist rocks; (?always) on acid soil.

Notes:
(1) The genus Codonoboea, originally consisting of three species (Ridley 1923) was included in Henckelia by Weber & Burtt (1998). By the redefinition of Henckelia (Weber et al. 2011), Codonoboea emerged as an enormously enlarged genus. Presently, around 150 species are recognised, the bulk of them (around 100) occurring in the Malay Peninsula. The species transfers from Henckelia to Codonoboea were made by Kiew & Lim (2011), those outside Peninsular Malaysia (Sumatra, S Thailand, Borneo, Philipines) by Middleton et al. (2013), that of Sulawesi and New Guinea (H. kjellbergii) by Kartonegoro (2012).
(2) There are good reasons to believe that the high species number in the Malay Peninsula is for a great part due to very narrow species concepts. It is evident that some widespread species have produced local variants in isolated localities (e.g., mountains of the Main Range). These variants are traditionally recognised as species, but scarcely deserve that rank.
(3) New species are continuously described, especially from Peninsular Malaysia. Whether they will withstand critical examination, remains to be seen.
(4) From the many sections formerly established in Didymocarpus (see synonyms above) only sect. Heteroboea is monophyletic (Lim & Kiew 2020).

Selected references: Ridley, Fl. Malay Penins. 2 (1923); Weber & Burtt, Beitr. Biol. Pflanzen 70(1-2): 293-363 (1998); Kiehn et al., Beitr. Biol. Pflanzen 70(1-2): 407-444 (1998), chrom. numb.; Weber et al., Taxon 70: 60(3): 767–790 (2011), mol. phyl.; Kiew & Lim, Garden's Bull. Singapore 62(2): 253-275 (2011) transfers; Middleton et al., Edinburgh J. Bot. 70(3): 385–404 (2013), transfers; Kartonegoro, Edinburgh J. Bot. 69(2): 360 (2012), transfer; Lim & Kiew, Reinwardtia 14(1): 13-17 (2014), Codonoboea sections.

Tax. details, cytology, and bibliography: Gesneriaceae Resource Centre (GRC). Royal Botanic Garden Edinburgh.

Page content and update responsibility/contact: Anton Weber.
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(A) Codonoboea species with opposite leaf arrangement, usually branched inflorescences and ring- or cup-shaped nectary (corresponding to Henckelia sect. Didymanthus sensu Weber & Burtt 1998)

(B) Codonoboea species with alternate leaf arrangement, single-flowered inflorescences and ring- or cup-shaped nectary (corresponding to Henckelia sect. Heteroboea sensu Weber & Burtt 1998)

(C) Codonoboea species with alternate leaf arrangement, usually branched inflorescences and unilateral (often tripartite) nectary (corresponding to Henckelia sect. Glossadenia sensu Weber & Burtt 1998)