Cayratia emarginata ( Vitaceae ) , a new species from Thailand and Vietnam

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RESEARCH ARTICLE InTRoduCTIon
De Loureiro (1790) published the genus Columella based on the type species Columella pedata Lour.Later, Columella was renamed Cayratia by De Jussieu (1818) so as to distinguish it from two other similarly named genera.Planchon (1887) treated Cayratia under Cissus L. sect.Cayratia while Gagnepain (1911) finally considered Cayratia and Cissus as separate genera.
Cayratia is a tropical and subtropical genus distributed in Asia, Africa, Australia and the Pacific Islands, comprising 63 species (Wen 2007).In Thailand it contains 6 species, none of them endemic.

Cayratia emarginata
Generally in Thai Cayratia the habit type seems to be correlated with seed morphology.Thus, species with herbaceous habit have seeds with an adaxial side with 2 faces and lack a deep cavity and occluding membrane, while species with a woody habit have seeds with their adaxial side possessing a cavity occluded by a membrane.Although no C. emarginata seeds have been seen, it is likely that if this character correlation is maintained, this species has seeds with an adaxial side with 2 faces and no cavity.
The specimen collected in the Sa Kaeo province, had a sticky secretion on the stems.In addition, all of the specimens examined grow in limestone terrain.
We have used as a holotype the duplicate of the specimen held in P, because it contains flowers and is a good representative of the species.This specimen was previously identified as Cayratia mollissima.It can be easily differentiated from it because C. emarginata has a herbaceous habit and its leaves are generally much smaller (3 -6 by 1.5 -3 cm), while C. mollissima has a woody habit and bigger leaves (7-20 by 2.5 -10 cm).