Wen-Hong Chen

LITOSTIGMA , A NEW GENUS FROM CHINA: A MORPHOLOGICAL LINK BETWEEN BASAL AND DERIVED DIDYMOCARPOID GESNERIACEAE

Litostigma , a new Chinese genus of Gesneriaceae, is described and illustrated. It is characterised by its large flowers in comparison to its small leaves; slightly revolute leaf margins; 1-flowered cymes; crateriform or disciform stigma; and long ovoid capsule. Rather surprisingly, Litostigma falls among the basal didymocarpoid Gesneriaceae. Two new species, Litostigma coriaceifolium Y.G.Wei, F.Wen & M.Moller and Litostigma crystallinum Y.M.Shui & W.H.Chen, are described.

Three New Species of Petrocodon (Gesneriaceae), Endemic to the Limestone Areas of Southwest China, and Preliminary Insights into the Diversification Patterns of the Genus

Abstract Three new species of Gesneriaceae, Petrocodon ainsliifolius, Petrocodon lithophilus, Petrocodon viridescens , from limestone areas of Yunnan, China are described and illustrated. Their independent species status is demonstrated in phylogenetic analyses using nuclear ribosomal internal transcribed spacer and chloroplast trnLF intron-spacer sequences. The phylogenetic and taxonomic relationships with their congeners are discussed from a morphological point of view. Morphological convergences, particularly of the flower, appear to characterize this calciphilous genus. Preliminary results are based on the material included, phylogenetic relationships inferred, and geographic distributions. The limestone area in Southeast Yunnan and West Guangxi appears as the center of origin and diversification of Petrocodon, with separate range expansions to eastern karst regions.

Taxonomic status, phylogenetic affinities and genetic diversity of a presumed extinct genus, Paraisometrum W.T. Wang (gesneriaceae) from the karst regions of Southwest China.

Background The karst regions in South China have an abundance of endemic plants that face high extinction risks. The Chinese Gesneriaceae endemic Paraisometrum mileense ( = Oreocharis mileensis), was presumed extinct for 100 years. After its re-discovery, the species has become one of five key plants selected by the Chinese forestry government to establish a new conservation category for plants with extremely small populations. For conservation purposes, we studied the phylogenetic and population genetic status of P. mileense at the three only known localities in Guangxi, Guizhou and Yunnan. Methodology/Principal Findings We collected 64 samples (52 species) of Oreocharis and 8 samples from three provinces of P. mileense and generated molecular phylogenies, and inferred that P. mileense represents a relatively isolated and derived taxonomic unit within Oreocharis. Phylogeographic results of 104 samples of 12 populations of P. mileense indicated that the populations in Yunnan have derived from those in Guangxi and Guizhou. Based on AFLP data, the populations were found to harbor low levels of genetic diversity (He = 0.118), with no apparent gradient across the species’ range, a restricted gene flow and significant isolation-by-distance with limited genetic differentiation among the populations across the three provinces (F ST = 0.207, P<0.001). The 10 populations in Yunnan were found to represent two distinct lineages residing at different altitudes and distances from villages. Conclusion/Significance The low levels of genetic diversity found in P. mileense are perhaps a consequence of severe bottlenecks in the recent past. The distribution of the genetic diversity suggests that all populations are significant for conservation. Current in situ and ex situ measures are discussed. Further conservation actions are apparently needed to fully safeguard this conservation flagship species. Our work provides a model of an integrated study for the numerous endemic species in the karst regions with extremely small populations.

Seven new species of Begonia (Begoniaceae) in Northern Vietnam and Southern China

Abstract Since 2016, KIB (Kunming Institute of Botany) and CPC (Centre for Plant Conservation of Vietnam) have conducted several surveys in the transboundary karst regions in Northern Vietnam and Southern China and seven new species in the genus Begonia Linn. (Begoniaceae) are firstly described. Amongst them, two species, Begonia albopunctata Y.M. Shui, W.H. Chen & H.Q. Nguyen and B. erectocarpa H.Q. Nguyen, Y.M. Shui & W.H. Chen, respectively belong to section Sphenanthera with berry fruits and section Leprosae with clavate berry fruits; four species, B. gulongshanensis Y.M. Shui & W. H. Chen, B. minissima H.Q. Nguyen, Y.M. Shui & W.H. Chen, B. mollissima Y.M. Shui, H.Q. Nguyen & W.H. Chen, B. rhytidophylla Y.M. Shui & W.H. Chen, belong to section Coelocentrum with parietal placentation; one species, Begonia bambusetorum H.Q. Nguyen, Y.M. Shui & W.H. Chen, belongs to section Diploclinium with 3-loculed ovary and capsules. The diagnostic characters of these species are described and illustrated in the text and photographs.

Ancylostemon dimorphosepalus (Gesneriaceae), a new species from China

A new species of Gesneriaceae, Ancylostemon dimorphosepalus W.H. Chen & Y.M. Shui, is described and illustrated. It is characterized by its cordate leaves, purple flowers, dimorphous sepals, and small upper lobes of the corolla. Its relationships with the similar species, Ancylostemon aureus and Oreocharis rotundifolia, are discussed.