Hedyotiskonhanungensis (Rubiaceae): A new species from the central highlands of Vietnam.

A new species of Hedyotis L. (Rubiaceae), Hedyotiskonhanungensis B.H. Quang, T.A. Le, K.S. Nguyen & Neupane, is described and illustrated from the central highlands of Vietnam based on morphological and phylogenetic evidence. The new species belongs to the morphologically diverse tribe Spermacoceae (ca. 1000 species) of the family Rubiaceae, which is represented by 70-80 species in Vietnam. The phylogenetic analysis, based on four DNA regions (ITS, ETS, petD, rps 16), confirms the new species' placement within the genus Hedyotis - one of the largest genera in the tribe, comprising ca. 180 species across Asia and the Pacific. Hedyotiskonhanungensis is morphologically distinct from all southeastern Asian Hedyotis L. in its set of traits such as leaf type (shape and thickness), growth habit, and floral parts (color of inflorescence axis and the shape of calyx lobes). The new species shows similarities with Hedyotisshenzhenensis, H.shiuyingiae, and H.yangchunensis from China in its herbaceous habit, fleshy ovate leaf blades, and dark purple floral parts, but it is phylogenetically distinct and can be distinguished from them by the following combination of morphological traits: habit with slightly smaller stature (<25 cm), broadly ovate or deltoid stipules with cuspidate apex and entire margin, and ovate or nearly ovate calyx lobes.

Parahellenia, a new genus segregated from Hellenia (Costaceae) based on phylogenetic and morphological evidence.

Previous studies recognized three major lineages of the family Costaceae: a South American clade, an Asian clade and a Costus clade. However, the genus Hellenia within the Asian clade has been shown to be non-monophyletic and its morphology has not been studied carefully. Therefore, the complete plastid genomes of Hellenia species were obtained and the monophyly of Hellenia was tested through four different datasets in this study. Plastid phylogenomic analyses of Costaceae revealed that Hellenia is strongly supported as paraphyletic. Two major clades are recovered, namely the Hellenia s.s. subclade and the Parahellenia subclade. Phylogenetic analyses based on an enlarged taxon sampling of the Asian clade using a two chloroplast markers dataset (trnK intron and trnL-F spacer) confirmed the paraphyly of Hellenia. Meanwhile, morphological analyses suggested that members of the Parahellenia subclade differ from the remaining Hellenia species in many characters including inflorescences, bracts, stigma, axillary buds, floral tubes and labellum. According to the present molecular and morphological evidence, the latter subclade is recognized as a new genus, Parahellenia. Two new species are described, four new combinations are made, and identification keys are also provided.

Hemiboeachanii (Gesneriaceae), a new species from limestone areas of northern Vietnam.

Hemiboeachanii, a new species of Gesneriaceae from Ha Giang Province, northern Vietnam, is here described and illustrated. It has many branched stems, diamond-shaped involucre with two cirrose opposite apices, a pink corolla, red spotted inside, and a flowering time in January-February. Among congeners with an externally hairy corolla, this new species is morphologically close to H.crystallina and H.sinovietnamica. Diagnostic discriminative characters in all mentioned species are discussed. The conservation status of this species is considered to be "Critically endangered" (CR) according to the IUCN Red List Categories and Criteria.

Spiradiclisdetianensis (Rubiaceae, Ophiorrhizeae), a new species from southwestern Guangxi, China.

A new species of Rubiaceae, Spiradiclisdetianensis is described from a limestone karst area of southwestern China. This new species is morphologically similar to S.cordata and S.spathulata. All of them have rosetted habit and long peduncles, but it differs from the former by the cuneate leaf bases (vs. basally cordate) and much longer corolla tubes (1.8-2.2 cm long vs. ca. 5 mm long), and from the latter mainly by its tubular-funnel shaped corolla (vs. slenderly salver shaped), 4.5-6.8 (vs. 1.5-2) mm in diam, inside throat and corolla densely puberulent (vs. glabrous except a ring of long hairs at the middle). It also resembles to S.tubiflora, but differs clearly by its subrosulate habit (vs. procumbent to creeping), longer leaf blades (7.0-10.5 cm vs. 0.5-2.5 cm) and longer corolla tubes (18-22 mm vs. 14-16 mm). At same time, color photos, illustrations, detailed descriptions and conservation status of the new species are provided.

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).

Leptomischus hiepii, a new species of Rubiaceae from Vietnam.

Leptomischus hiepii, a new species of the tribe Argostemmateae from Son La province, northwestern Vietnam, is described and illustrated. Morphologically it allies to L. wallichii, L. erianthus and L. funingensis by sharing a similar habit, large stipules and similar corolla shape, but it differs by its anisophyllous leaves, 1-flowered inflorescences, homostylous flowers and tubular-campanulate corollas.

Rediscovery of Angiopteris tonkinensis (Marattiaceae) after 100 years, and its revision.

The border area between south-eastern Yunnan, China and northern Vietnam is one of the regions with richest biological diversity including that of the fern genus Angiopteris (Marattiaceae). Based on the analysis of morphology and DNA sequences of multiple chloroplast regions (atpB, rbcL, rps4-trnS spacer and trnL-F spacer), we revised Angiopteris tonkinensis (Hayata) J.M.Camus and proposed a new combination Angiopteris tamdaoensis (Hayata) J.Y.Xiang & T.Wang, comb. nov., which was previously regarded as a synonym of A. tonkinensis. We found support for a monophyletic Angiopteris including Protomarattia. This discovery adds two new distribution sites of A. tonkinensis, one in China (Malipo, Yunnan) and one in Vietnam (Quan Ba, Ha Giang). We suggest A. tonkinensis should be categorised as Critically Endangered (CR) species according to the criteria of IUCN.

Checklist to the Elatostema (Urticaceae) of Vietnam including 19 new records, ten new combinations, two new names and four new synonyms.

Elatostema (Urticaceae) comprises several hundred herbaceous species distributed in tropical and subtropical Africa, Asia, Australia and Oceania. The greatest species richness occurs on limestone karst in Southeast Asia. Taxonomic revisions of Elatostema are largely out of date and contradict each other with respect to the delimitation of Elatostema and Pellionia. Most herbaria in SE Asia and worldwide contain significant amounts of unidentified material. As part of a broader revision of Elatostema in SE Asia, we present an updated checklist for Vietnam based on field visits, a review of specimens in herbaria worldwide, a review of type material and nomenclature. We recognize 77 taxa (75 species and two infraspecific taxa) of Elatostema in Vietnam, 23 of which were previously ascribed to Pellionia. Nineteen of these are new records for the country, i.e., E. attenuatoides, E. austrosinense, E. backeri, E. brunneinerve, E. crassiusculum, E. crenatum, E. fengshanense, E. glochidioides, E. malacotrichum, E. nanchuanense, E. oblongifolium, E. obtusum, E. oppositum, E. pergameneum, E. prunifolium, E. pseudolongipes, E. pycnodontum, E. salvinioides and E. xichouense. We place E. baviensis in synonymy of E. platyphyllum, E. colaniae in synonymy of E. myrtillus, P. macroceras in synonymy of E. hookerianum, and P. tetramera in synonymy of E. dissectum for the first time. Fourteen taxa (18% of all the recognized taxa) are endemic to Vietnam, which makes Elatostema one of the richest genera for endemic species in this country; this level of endemism is comparable to levels observed in Orchidaceae. Our checklist suggests that the highest diversity and endemism of Elatostema occurs in northern Vietnam, and that there is the greatest floristic similarity of northern Vietnam to SW China. The relationship among floristic regions is also investigated. We could find no records of Elatostema for 33 out of 63 provincial units of Vietnam, including all the southernmost provinces. We propose that further studies on the diversity of Elatostema in central and southern Vietnam are severely needed.

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.

The historical demography and genetic variation of the endangered Cycas multipinnata (Cycadaceae) in the red river region, examined by chloroplast DNA sequences and microsatellite markers.

Cycas multipinnata C.J. Chen & S.Y. Yang is a cycad endemic to the Red River drainage region that occurs under evergreen forest on steep limestone slopes in Southwest China and northern Vietnam. It is listed as endangered due to habitat loss and over-collecting for the ornamental plant trade, and only several populations remain. In this study, we assess the genetic variation, population structure, and phylogeography of C. multipinnata populations to help develop strategies for the conservation of the species. 60 individuals from six populations were used for chloroplast DNA (cpDNA) sequencing and 100 individuals from five populations were genotyped using 17 nuclear microsatellites. High genetic differentiation among populations was detected, suggesting that pollen or seed dispersal was restricted within populations. Two main genetic clusters were observed in both the cpDNA and microsatellite loci, corresponding to Yunnan China and northern Vietnam. These clusters indicated low levels of gene flow between the regions since their divergence in the late Pleistocene, which was inferred from both Bayesian and coalescent analysis. In addition, the result of a Bayesian skyline plot based on cpDNA portrayed a long history of constant population size followed by a decline in the last 50,000 years of C. multipinnata that was perhaps affected by the Quaternary glaciations, a finding that was also supported by the Garza-Williamson index calculated from the microsatellite data. The genetic consequences produced by climatic oscillations and anthropogenic disturbances are considered key pressures on C. multipinnata. To establish a conservation management plan, each population of C. multipinnata should be recognized as a Management Unit (MU). In situ and ex situ actions, such as controlling overexploitation and creating a germplasm bank with high genetic diversity, should be urgently implemented to preserve this species.