Begonia catbensis (sect. Coelocentrum, Begoniaceae), a new species from northern Vietnam.

Begonia catbensis, a new species in Begonia sect. Coelocentrum is described and illustrated. The new species was discovered in lowland limestone hills at Cat Ba National Park and can be easily distinguished from all its congeners by having dendritic hairs on the petiole, adaxial veins and stipules, fimbriate bracts and bracteoles, dense conical bullae on the upper surface of the leaf blade, two tepals in the pistillate flowers and a glabrescent ovary with verrucose wings. Based on IUCN Criteria, the species is currently assessed as "Endangered" (D).

Gesneriaceae in China and Vietnam: Perfection of taxonomy based on comprehensive morphological and molecular evidence.

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Reassessment of Bournea Oliver (Gesneriaceae) based on molecular and palynological evidence.

The former genus Bournea is endemic to China, including two species, has been under consideration for incorporation into the expanded genus Oreocharis s.l. in Gesneriaceae. The phylogenetic tree inferred from two DNA sequences (trnL-F and ITS) showed that this genus is deeply nested into Oreocharis s.l. However, the new tree from seven ones (atpB-rbcL, ndhH-rps15-ycf1, rpl132, trnC-trnD, trnL-F, trnT-trnL of chloroplast DNA and ITS regions) revealed that Bournea is the sister group of other of Oreocharis s.l. Furthermore, Bournea is morphologically different from other Oreocharis based on existing data. We suggest keeping Bournea as an independent genus in Gesneriaceae.

Oreocharis jasminina (Gesneriaceae), a new species from mountain tops of Hainan Island, South China.

A new species of Gesneriaceae, Oreocharis jasminina S.J.Ling, F.Wen & M.X. Ren from Hainan Island, south China, is highlighted and described. The new species is distinguished by its actinomorphic corolla, narrow floral tube and ovate anthers hidden in the floral tube. The new species also showed clear geographic and altitudinal isolation from the three currently-recognised Oreocharis species on the Island. Molecular phylogenetic analysis, based on nuclear ITS1/2 and plastid trnL-trnF sequences, supported the delimitation of the new species, which forms a single lineage with all the other Oreocharis species from Hainan Island. The roles of geographic and floral isolation in the evolution of the new species and its affinities are discussed.

Two new species of Allocheilos (Gesneriaceae) from the karst regions in Yunnan, China.

Allocheilos W.T.Wang in Gesneriaceae was described in 1983 and is characterized by its 4-lobed adaxial lip and undivided abaxial lip with acute apex. The genus is endemic to the karst regions in southwestern China and is classified as endangered due to habitat loss. During surveys of the karst areas in Yunnan of southwestern China in 2017, we collected two unknown species of the genus and later confirmed their novelty to science based on the detailed observation of their morphological characteristics, viz. A. maguanensis W.H.Chen & Y.M.Shui and A. rubroglandulosus W.H.Chen & Y.M.Shui. Their relationships with the similar species and provisional conservation status are discussed.

Deinostigma fasciculatum, a new species of Gesneriaceae in Yunnan, China.

A new species of Deinostigma (Gesneriaceae) from Yunnan, China, Deinostigma fasciculatum W.H.Chen & Y.M.Shui, sp. nov., has been discovered and described. In the genus, the new species is similar to D. cicatricosum (W.T. Wang) D.J. Middleton & Mich. Möller and D. cyrtocarpum (D. Fang & L. Zeng) Mich. Möller & H.J. Atkins in dark purple flowers and falcate fruit, but differs from them mainly in the inflorescences with fasciculate flowers, calyx lobes (reflexed, narrowly lanceolate and 1.2-1.3 cm long), corolla tubes (sharply contracted below middle and white outside and below throat). The above three species grow nearby non-limestone wet cliffs and geographically isolated with different distributions (the new species in Southeast Yunnan, D. cicatricosum in Eastern Guangxi and D. cyrtocarpum in Southern Guangxi and Guangdong, China).

Two new species of Paraboea (Gesneriaceae) in Caryota obtusa forests in Southwest China, with compound and simple dichasia, respectively.

Two new species of Gesneriaceae, Paraboea myriantha sp. nov. and P. brevipedunculata sp. nov. are described and illustrated with photos. They grow in the Caryota obtusa forests from Yunnan Province of China. P. myriantha is closely related to P. glutinosa (Hand.-Mazz.) K.Y.Pan, but differs mainly in corolla outside glandular-puberulent, adaxial corolla lobes semicordate, corolla tube obliquely campanulate, and filaments glandular-puberulent. P. brevipedunculata is closely related to P. crassifolia (Hemsley) B. L. Burtt, but different mainly in simple dichasia with 1 and 2 flowers, peduncles 0.5-2 cm long and capsules slightly twisted. The geographical relationship between the two new species and their similar species has been discussed.

Two new taxa of Gesneriaceae in the karst regions in North Vietnam.

One new species and one new variety of Gesneriaceae in Vietnam are described, viz. Paraboea sinensis var. glabrissimavar. nov. and Primulina xuansonensis sp. nov. These two new taxa grow in limestone regions in North Vietnam. The former new variety differs from Paraboea sinensis (Oliv.) Burtt var. sinensis in its young leaf abaxially, stem and peduncle sparsely and thin pannose, acute top of leaves, pistil glandular-pubescent or pubescent. The latter new species differs in its bracts 1.6-2.5 × 1.3-1.5 cm, corolla 3-3.5 cm long, corolla tube slightly curved near the base and inflated on the adaxial surface near the corolla lobes, and corolla abaxial lip lobes rounded. The two new taxa grow at Xuan Son National Natural Reserve, North Vietnam and remain undisturbed with low risk of extinction.

Four new species of Oreocharis (Gesneriaceae) in Yunnan province, China.

Four new species of Oreocharis (Gesneriaceae) are described and illustrated. These new species grow in pairs in montane forests in Yunnan province, China. One pair grows in Wenshan county, Southeast Yunnan, viz. Oreocharis eriocarpa W.H. Chen & Y.M. Shui and O. wenshanensis W.H. Chen & Y.M. Shui and another pair grows in Yongde county, Southwest Yunnan, viz. O. fulva W.H. Chen & Y.M. Shui and O. lacerata W.H. Chen & Y.M. Shui. Their morphological and geographical relationship with similar species is discussed and the IUCN endangered status is provided, based on the available data.

Rediscovery and amended descriptions of Begonia kingdon-wardii (Begoniaceae) from North Myanmar.

Begonia kingdon-wardii Tebbitt was rediscovered in 2014 from Myanmar after 67 years based on its last collection in 1937. Its previously unknown female flower and inaccurate morphology of leaf and ovary have been additionally described. This species belongs to Begonia sect. Sphenanthera (Hassk.) Warb. due to its dioecious habit, 3-locular ovary, berry fruits and thick placenta segments. Morphologically, it is similar to Begonia gulinqingensis S. H. Huang & Y. M. Shui in the leaf shape, placentation and fruit shape, but different in its dioecious plants, pliciform leaves, two-petalled female flowers and berry fruits. The rediscovery of this amazing living species will attract significant interest for scientific research and horticultural application.

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

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.

Two new species of Oreocharis (Gesneriaceae) from Fan Si Pan, the highest mountain in Vietnam.

Two new species of Oreocharis Benth. from Fan Si Pan, the highest mountain in Vietnam (Sa Pa) are described and illustrated. Oreocharis grandiflora W.H.Chen, Q.H.Nguyen & Y.M.Shui, is similar to O. flavida Merr. from Hainan province, China, but differs mainly by its larger and infundibuliform corolla, stamens adnate to the base of the corolla tube and stamens coherent in two pairs. The second, Oreocharis longituba W.H.Chen, Q.H.Nguyen & Y.M.Shui, is similar to O. hirsuta Barnett, endemic to northern Thailand, but mainly differs in its pubescence, coherent stamens and glabrous filaments.

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 (FST = 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.