Zingiber aureolinum, a new species from the Central Highlands of Vietnam, is described and illustrated here. Detailed description accompanied by photographic plates including flower dissection are provided and notes on distribution and preliminary conservation assessment of the new species are also presented. The new species belongs to Z. sect. Cryptanthium within which it is readily recognized by a character combination of creeping rhizomes and bright yellow flowers.

Boesenbergia monophylla (Zingiberaceae: Zingiberoideae), a new ginger species from Quang Ngai Province in Central Vietnam, is described and illustrated. The description is accompanied by additional notes on etymology, ecology, phenology, distribution, and preliminary IUCN assessment. The species is unique among all congeners in Cambodia, Laos and Vietnam by its monophyllous habit. For the diagnostic purposes it is compared to Boesenbergia prainiana, another monophyllous species occurring in Peninsular Malaysia and Thailand from which it can be recognised by dark green leaf blades with velvety appearance, petioles as long or longer than half of the length of the leaf blade, largely hidden inflorescence, and flowers pale-yellow with labellum ornamented with red central bands at basal half, widening and turning pink distally all the way to the margin. The novelty brings the total number of Boesenbergia species in Vietnam to seven. An updated key to the species of Boesenbergia in Vietnam is also provided.

Syzygium ngheanense (Myrtaceae), a new species from Nghe An Province, in Central Vietnam is described and illustrated. The species is most similar to S. vestitum, S. scarbum and S. levinei but differs from the three latter in having glabrous bracts and bracteoles, sparsely scabrid flower buds and hypanthia, larger sepals and petals, longer stamens and styles. Information on phenology, ecology and distribution is provided, together with a preliminary conservation status assessment and taxonomic notes for the new species and a key to distinguish it from three hairy Syzygium species in Indochina.

Many species are defined in the Musa section within its natural diversification area in Southeast Asia. However, their actual number remains debated as botanical characterisation, distribution and intraspecific variability are still poorly known, compromising their preservation and their exploitation as crop wild relatives of cultivated forms. To address the underexplored Musa diversity in mainland Southeast Asia, at the northern edge of the natural range, 208 specimens were collected in Vietnam, Laos and China, mainly belonging to Musa balbisiana, M. itinerans, M. acuminata and M. yunnanensis. Data on location, morphology, environment and local knowledge were recorded, and leaf samples collected for high-throughput genotyping. This study combines geographical, morphological, and genomic diversity to clarify the taxonomic classification. The collected species exhibit highly distinctive morphologies and genomes, just as they differ in ranges and life traits. Intraspecific genomic diversity was also observed, although not necessarily morphologically perceptible. Mainland Southeast Asia is confirmed as a primary diversification centre for the Musa section. The diversity observed is only partially represented in major international ex situ collections, calling for their urgent enrichment and the promotion of in situ management procedures, for the protection of these threatened species and to better harness their potential in breeding programmes. Although considered wild, the species studied are all affected to varying extents by human use. Musa yunnanensis and M. acuminata subsp. burmannica are the most strictly wild forms, with spontaneous interspecific hybrids first described in this study. Although gathered as fodder, they were only occasionally dispersed outside their endemic zones. Musa itinerans is not cultivated per se, but natural populations are widely exploited, leading to a geographically structured diversity. The diversity of M. balbisiana is widely distributed and geographically structured by human activities. This species should be regarded as domesticated. These various stages, from simple opportunistic gathering to true domestication, shed light on the evolutionary history of today’s cultivated varieties.

The current research describes a phytochemical analysis and antimicrobial activity of essential oils extracted from the leaves of two Vietnamese Annonaceae species Goniothalamus yunnanensis W.T.Wang and G. touranensis Ast. By the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analyses, sesquiterpene hydrocarbons accounted for the highest percentage of 68.22 % in G. yunnanensis leaf essential oil with bicyclogermacrene (31.03 %) and (E)-caryophyllene (21.12 %) being the main compounds. G. touranensis leaf essential oil was dominated by monoterpene hydrocarbons (57.08 %) with p-cymene (19.95 %) and α-pinene (16.82 %) being the major compounds. By the microdilution broth susceptibility assay, two oil samples showed strong antibacterial effects on the Gram-positive bacteria Enterococcus faecalis ATCC51299, Staphylococcus aureus ATCC29213, and Bacillus cereus ATCC11778 with the MIC values of 16-64 μg/mL. They also inhibited the growth of the yeast Candida albicans ATCC 60193 with the same MIC value of 128 μg/mL. From the vector-based intervention approach, both oil samples showed strong mosquito larvicidal activity against four-instar larvae of Aedes aegypti and Ae. albopictus with the 24 h LC50 values of 16.75-27.60 μg/mL and 24 h LC90 values of 24.31-46.18 μg/mL. Docking results indicated that bicyclogermacrene and p-cymene exhibited the highest ΔG (binding affinity) values of -8.208 and -6.799 kcal/mol with the olfactory binding proteins (OBPs) of Ae. aegypti and Ae. albopictus, respectively.

The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1-89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M. caudata leaf oil. C. vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9-62.0 %) and limonene (10.3-16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C. vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C. vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC50 values of 7.67 and 6.73 μg/mL, and the respective LC90 values of 13.37 and 10.83 μg/mL. In the same manner, C. vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC50 values of 12.37 and 12.00 μg/mL, and the LC90 values of 20.56 and 18.58 μg/mL, respectively. C. vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M. caudata essential essential oils in both two biological assays.

Banana bunchy top virus is a multicomponent circular ssDNA virus (family Nanoviridae) that causes one of the most devastating diseases of cultivated bananas and plantains (family Musaceae). It is transmitted by the aphids Pentalonia nigronervosa and P. caladii among host plants of Musaceae and some other families of monocots. Our Illumina sequencing reconstruction of virome components of BBTV-infected banana plants and their neighbor non-banana plants sampled in Vietnam and Laos revealed the monocot Commelina sp. (Commelinaceae) and the dicots Bidens pilosa and Chromolaena odorata (both Asteraceae) as hosts of BBTV and circular ssDNA alphasatellites (family Alphasatellitidae). Counting the proportions and relative abundances of Illumina reads representing BBTV genome components and alphasatellites suggested that Chromolaena and Commelina are poor hosts for BBTV and one to three alphasatellite species, whereas Bidens is a permissive host for BBTV and four alphasatellite species representing two genera of Alphasatellitidae. Our findings provide evidence for the dicot plants of family Asteraceae as alternative hosts of BBTV and its alphasatellites, which warrants further investigation of these and other dicots as a potential refuge and source of BBTV and multiple alphasatellites that become associated with this virus and likely affect its replication, transmission, and host range.

A genus and species of palm from the Truong Son Range in Vietnam, Truongsonia lecongkietii, is described as new to science. Phylogenomic analysis strongly supports the placement of the new taxon in subfamily Arecoideae as sister to the African endemic tribe Podococceae, which comprises a single genus Podococcus. A new tribe Truongsonieae is also described to accommodate Truongsonia in the current phylogenetic classification of palms. Truongsonia is a dwarf, acaulescent, clump-forming palm bearing entire, bifid leaves with a fibre-like extension of the rachis through the sinus of the two lobes of the leaf. The interfoliar inflorescence is exserted on a long peduncle with 3­–4 tightly sheathing peduncular bracts and rachillae presented at the apex only. The ovary is triovulate-tricarpellate, but fruits are single-seeded. Truongsonia is Critically Endangered, with surveys locating only 10–15 plants in the wild. Swift conservation action is required to secure the future of this remarkable and phylogenetically isolated lineage of palms.

The southern part of the Mekong Delta Limestones of Vietnam (MDL-HC or Hon Chong karst) comprises numerous small limestone hills. It is a hotspot of biodiversity for soil and cave invertebrates. Here, we synthesize the results of biological surveys carried out in Hang Mo So, the richest MDL-HC cave for troglobionts, and in surrounding karsts. Methodologies for the ecological characterization of species are discussed, with emphasis on parallel sampling (external soil plus cave). Hang Mo So has 27 troglobionts, including many still undescribed. An additional 40 cave-obligate species are known from other caves of MDL-HC. Among them, several are expected to be found in Hang Mo So. Most troglobionts of MDL-HC are endemic. Several relictual taxa without close relatives in Southeast Asia occur in Hang Mo So and in MDL-HC, reflecting an ancient origin of the fauna. The reasons for this richness are uncertain, but the cause of its current destruction—quarrying—is all too evident. Most of the original 4 km2 of the MDL-HC karst has been destroyed or soon will be, ultimately leaving only 1.6 km2 unquarried. Endemic species linked to karst habitats are, therefore, under clear threat of extinction. The Hon Chong karst (MDL-HC) was listed among the ten most endangered karsts on the planet 25 years ago. Today it would probably top the list.

With the aim of inferring phylogenetic relationships among 86 species (including 45 species from Vietnam) mostly of the subfamily Convallarioideae (=Nolinoideae) (Asparagaceae sensu APG IV), we analyzed their chloroplast DNA sequences (rbcL and trnL-F) by both Bayesian inference (BI) and maximum likelihood (ML) methods. Our dataset included six of the seven tribes classified in this subfamily; Convallarieae, Dracaeneae, Liriopeae Nolineae, Polygonateae and Rusceae (Eriospermeae not examined). Our study supported the sisterhood between Convallarioideae and Asparagoideae and the monophyly of all the tribes except Polygonateae. Within the Convallarioideae we examined, Dracaena formed the basalmost clade. Theropogon did not positively nest in any of the tribes including Convallarieae in which it had often been classified. It was weakly defined as the second basalmost branch. Ruscus (Rusceae) nested in Polygonateae as the sister to Maianthemum, hence Polygonateae was recognized here as paraphyletic. Nolineae was discordant in position between BI and ML analyses, probably reflecting the limited molecular markers we examined. In both BI and ML analyses, all genera of Liriopeae and Convallarieae were monophyletic and their intergeneric relationships were consistent. In Liriopeae, Liriope was sister to the clade of Ophiopogon + Peliosanthes. In Convallarieae, Aspidistra + Tupistra formed the sister clade to Reineckea + Rohdea. Interspecific relationships within these genera were, however, not clearly resolved, except for several pairs of sister species. We also briefly discussed some of the resultant phylogenetic relationships from the morphological and/or evolutionary aspects.

Zingiber is a genus of medicinal plants containing a rich resource of essential oils. The current study aims to describe chemical analysis and antimicrobial assay for two Zingiber species Zingiber eberhardtii Gagnep. and Z. skornickovae N.S. LATIN SMALL LETTER Y WITH ACUTE. The rhizome oils, which were obtained by hydro-distillation using a Clevenger apparatus, were analyzed by GC-MS (gas chromatography-mass spectrometry). Extraction of Z. eberhardtii rhizome gave a yellow oil with 41 identified compounds (96.3%), in which linalool (34.9%) and 1,8-cineole (12.7%) were the principal compounds. The yellow oil of Z. skornickovae rhizome included 53 identified compounds (97.8%), with & beta;-pinene (25.0%), (E)-caryophyllene (8.8%), and & alpha;-pinene (7.9%) as the major agents. By broth dilution method, both oils moderately controlled the growth of Gram (+) bacteria Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 25923 with the same MIC (minimum inhibitory concentration) value of 128 & mu;g/mL. In particular, Z. skornickovae rhizome oil showed the best antimicrobial activity against yeast Saccharomyces cerevisiae ATCC 4098 with a MIC value of 64 & mu;g/mL. The obtained results are promising information for future research.

AbstractThe current study describes chemical compositions and antimicrobial activity of essential oils from the rhizome of two Vietnamese ginger plants Newmania orthostachys N.S. Lý & Škorničk. and Newmania serpens N.S. Lý & Škorničk. 49 compounds (98.4%) were identified in N. orthostachys rhizome oil, whereas 54 compounds (93.4%) were identified in N. serpens rhizome oil. N. orthostachys rhizome essential oil was dominated by monoterpene hydrocarbons (74.2%), in which β-pinene (35.7%), α-pinene (13.4%), sabinene (8.0%), camphene (6.7%), and limonene (5.1%) were characteristic compounds. Monoterpene hydrocarbons (33.5%) and sesquiterpene hydrocarbons (44.1%) represented N. serpens rhizome essential oil, as well as β-pinene (18.5%), bicyclogermacrene (12.4%), β-selinene (8.2%) were the principal compounds. In an antimicrobial assay against three tested Gram-positive bacteria Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579, both two essential oils showed the minimum inhibitory concentration (MIC) values of 16-64 µg/mL lower than those of positive control Streptomycin (MIC 128-256 µg/ml). These two essential oils with the MIC values of 8-16 µg/mL are also better than the positive control cycloheximide (MIC 32 µg/mL) against the yeast Candida albicans ATCC 10231.Keywords: Newmaniaessential oilchemical compositionantimicrobial activity

Abstract The chemical constituents and antimicrobial activities of essential oils isolated from the leaf and stem of Piper albispicum C. DC. were reported. The main compounds of the leaf essential oil were chavicol acetate (16.3%), bicyclogermacrene (13.8%), sabinene (8.6%), b-pinene (7.7%) and a-pinene (7.3%). On the other hand b-pinene (15.6%), a-pinene (14.6%) and bicyclogermacrene (13.2%) were the significant compounds of the stem essential oil. The leaf oil displayed the best antimicrobial activity towards Pseudomonas aeruginosa ATCC27853 with the Minimum inhibitory concentration (MIC) value of 5.82 µg/mL. Both essential oils exhibited similar activities against Enterococcus faecalis ATCC299212 (MIC’s, 9.07 µg/mL and 9.81 µg/mL, respectively) and Candida albicans ATCC 10231 (MIC’s, 10.66 µg/mL and 10.91 µg/mL, respectively). However, the stem oil exhibited pronounced activity against Staphylococcus aureus ATCC25923 and Bacillus cereus ATCC14579, with MIC values of 10.22 µg/mL and 10. 44 µg/mL, respectively. However, the studied essential oils did not inhibit the growth of Escherichia coli ATCC 25922 and Salmonella enterica ATCC13076. This is the first report on the chemical constituents and antimicrobial activity of the essential oil of P. albispicum.

Conamomum vietnamense, a new species of Zingiberaceae, is described and illustrated from Tay Nguyen (Central Highlands), Vietnam. It is most similar to C. odorum and C. rubidum, but differs in having well-developed stilt roots, elliptic leaf blades, narrowly ovate bracts, abaxially pubescent bracteoles, longer calyx with 2 truncate lobes, broadly obovate to orbicular glabrous labellum, longer filament and glabrous style. Data on distribution, habitat, vernacular name, conservation status and a colour plate of the new species, along with a key to distinguish the species of Conamomum in Cambodia and Vietnam are given.

Essential oils of the leaves of 4 Vietnamese Zingiberaceae species were first obtained by hydro-distilled, and their chemical compositions were identified by gas chromatography-flame ionization detection/mass spectrometry . β-Pinene (21.7%), sabinene (12.8%), and α-pinene (8.0%) were the main compounds in Wurfbainia tenella leaf oil. The essential oil of Hedydium villosum var. tenuifolium leaf was dominated by β-pinene (23.7%), β-caryophyllene (21.6%), and 1,8-cineole (14.0%). β-Pinene (27.4%), α-pinene (21.2%), limonene (12.1%), and myrcene (8.6%) were the characteristic components of Meistera sudae leaf oil, and β-pinene (32.8%) and ( E)-methyl cinnamate (15.8%) of Alpinia hongiaoensis leaf oil. The 4 oil samples exhibited antimicrobial activity against Bacillus subtilis (American Type Culture Collection [ATCC] 27212), Staphylococcus aureus (ATCC 12222), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 25923), Aspergillus niger (ATCC 9763), Fusarium oxysporum (ATCC 48112), Candida albicans (ATCC 10231), and Saccharomyces cerevisiae (ATCC 2601) at different levels. Especially, the leaf oil of M sudae showed strong activity against B subtilis, S aureus, and S cerevisiae with a minimum inhibitory concentration (MIC) value of 25.0 µg/mL.

Tupistra annamensis, a new species from central Vietnam is described and illustrated. In the habitats it occurs as an epiphyte or a lithophyte. Having a pendulous scape, this species is similar to such species as T. fungilliformis and T. clarkei, but differs distinctly from them and all other members of this genus by its outer and inner floral bracts subsimilar in size and shape, and sharply acute or aristate, somewhat glumaceous bracts exceeding the flowers. Besides data on the morphological and ecological traits of the new species, we provide notes on its systematic relationships as well.

Camellia annamensis , a new species of Camellia sect. Piqueti a (Theaceae) from central Vietnam is described and illustrated. It is most similar to Camellia l o n g i i , but differ s by its mature leaves sparsely appressed puberulous abaxially and leaf margins shallowly and widely denticulate , lateral veins 10-13 pairs , sparsely appressed puberulous petioles , sepals 5 , petals 20-22 , flattened-globose ovary and styles tomentose and free to base. Information on distribution , ecology , phenology , vernacular name , uses and conservation assessment of this new taxon, along with a key to distinguish the species of Camellia sect. Piquetia in Vietnam ar e also provided.