Dorcoceras

Dorcoceras

Full name and orig. publication: Dorcoceras Bunge, Enum. Pl. China Bor.: 128 ("1832", March 1833).

Etymology: The name is composed of the Greek δορκάς, dorkas = deer, roe, gazelle, and κερας, keras = horn. It means that the fruits are twisted like the horn of a gazelle.

Synonyms: -

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

Description (from Puglisi & Middleton 217: 11): Rosulate herbs. Leaves spirally arranged (or opposite in China), petiolate or sessile; lamina with a glandular or eglandular indumentum on the abaxial surface, adaxial surface eglandular hairy or some-times glabrous. Inflorescence axillary, cymose or at least ending in a cyme. Calyx with five sepals, almost free. Corolla pale purple to purple, obliquely campanulate, ventricose, with a broad throat; upper lobes reflexed. Stamens 2, filaments straight, anthers attached to filaments at point of thecae divergence, coherent; staminodes 3, reduced. Ovary glabrous or with some indumentum, unilocular with 2 parietal placentae, ovules many; stigma bilabiate or capitate. Fruit a twisted capsule, orthocarpic, bivalved, dehiscing longitudinally. Seeds small, brown and elliptic.

Chromosome number: n =9, 2n = 18 (D. hygrometricum Bunge, as Boea hygrometrica (Bunge) R.Br.; Kiehn & al. 1998).

Species number: 6 (4 in Thailand).

Species names (given only in case of few species): D. brunneum C.Puglisi, D. geoffrayi (Pellegr.) C.Puglisi [= Boea geoffrayi Pellegr.], D. glabrum C.Puglisi, D. hygrometricum Bunge, D. philippense Schltr., D. wallichii (R.Br.) C.Puglisi [= Boea wallichii R.Br., Didymocarpus helicteroides Wall., nom. nud.].
Another three species referred to Dorcoceras by Schlechter (1923) are now in Paraboea [P. crassifolia (Hemsl.) B.L.Burtt, P. rufescens (Franch.) B.L.Burtt] and Damrongia [D. clarkeana (Hemsl.) C.Puglisi].

Type species: Dorcoceras hygrometricum Bunge

Distribution: India, Myanmar, China, Thailand (4 species), Laos, Cambodia, Vietnam, Philippines and Indonesia.

Ecology: Growing on limestone or sandstone rocks in dry evergreen or mixed deciduous forest.

Notes: The resurrection of Dorcoceras resulted from the molecular-systematic studies of Puglisi et al (2016), which showed that the genus Boea, as understood by Burtt (1984), must be split into two genera:
(1) Boea s.str., becoming a genus of 10 species of Australasian distribution, and
(2) Dorcoceras, with distribution in SE Asia.

Selected references: Schlechter, Bot. Jahrb. Syst. 58: 255-379 (1923); Burtt, Notes Roy. Bot. Gard. Edinburgh 41: 401-452 (1984), rev. Boea & Paraboea; Kiehn & al., Beitr. Biol. Pflanzen 70: 407-444 (1998, "1997"), chrom. numb.; Puglisi, Taxon 65: 277-292 (2016), mol. syst., rev. Loxocarpinae; Puglisi & Middleton, Thai Forest Bull., Bot. 45(1): 10-17 (2017), reg. rev. (Thailand).

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

Page content and update responsibility/contact: D.J. Middleton.
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