Background
In our recent molecular phylogenetic study of Asian Begonia, two undescribed species, B. guixiensis sp. ined. (S. Guangxi, China) and B. longa sp. ined. (Vietnam), were sampled and placed within the strongly supported clade composed of Begonia sect. Coelocentrum and other co-distributed rhizomatous species in the Sino-Vietnamese limestone karsts. While Begonia sect. Coelocentrum has been recircumscribed based on the phylogenetic relationships, B. guixiensis sp. ined. and B. longa sp. ined. remain illegitimate names. In continuation of our studies in Asian Begonia, these two new species are described and illustrated.
Begonia longa
photo by Ching-I Peng et al, 2014.
Begonia longa
photo by Ching-I Peng et al, 2014.
vôi rừng cây lá rộng tại huyện Quản Bạ của Hà Giang. Chúng ra hoa vào tháng 4 đến tháng 8, hoa có màu tổng thể là màu trắng, nhị vàng. Loài này được
Begonia guixiensis
photo by BVN
Begonia guixiensis
photo by Ching-I Peng et al, 2014
Distribution map of Begonia longa and Begonia guixiensis In Vietnam
photo by Ching-I Peng et al, 2014
Results
Begonia guixiensis resembles B. cylindrica in the peltate, subcoriaceous leaves, differing by the shape of ovary/fruit and the type of placentation. In aspect, B. longa bears a superficial resemblance to B. brevipedunculata in leaf shape in particular, differing by many other features such as the long internodes, shorter petioles and smaller leaves, longer peduncles and 3-locular ovary. The chromosome number of both new species is determined as 2n = 30.
Conclusion
A careful study of the literature, herbarium specimens and living plants, both in the wild and in cultivation in the experimental greenhouse, support the recognition of the two new species, which are described and illustrated herein.