Two new species from Sulawesi and Borneo facilitate phylogeny and taxonomic revision of Engelhardia (Juglandaceae).

Engelhardia, a genus of Juglandaceae (the walnut family), is endemic to tropical and subtropical Asia. The rich Cenozoic fossil records and distinctive morphological characters of the living plants have been used to explore the evolutionary history and geographic distribution of Juglandaceae. However, the taxonomy of this genus has been suffered from a lack of in-depth investigation and good specimens across its distribution ranges. Species delimitation of Engelhardia was defined with seven species in 2020, but detailed information on the circumscription of the species still remains poorly understood. In this study, two new species are described from Sulawesi and Borneo, Engelhardia anminiana and E. borneensis. We also revised and reconstructed the phylogeny within Engelhardia using morphological, molecular (plastid and ribosomal), and distribution data. We sampled 787 individuals in 80 populations, and all the samples were genotyped using plastid regions, trnS-trnG, rps16, trnL-trnF, psbA-trnH, and rpl32-trnL; one ribosomal region, nuclear ribosomal internal transcribed spacer (nrITS). The all datasets were used to reconstruct the phylogenetic relationships. Then, the molecular analyses were combined for 738 sheets of specimens with 15 morphological characteristics to further explore the morphological clusters of Engelhardia. Cluster analysis using morphological data confirmed the delimitation of nine Engelhardia species. Also, phylogenetic analysis based on molecular data (i.e., plastid and ribosomal) supported the monophyly of Engelhardia and generated phylogenetic trees that included E. fenzelii, E. roxburghiana, E. borneensis, E. hainanensis, E. anminiana, E. serrata, E. villosa, E. apoensis and the varieties of E. spicata (i.e., E. spicata var. spicata, E. spicata var. rigida, E. spicata var. aceriflora, and E. spicata var. colebrookeana). Our comprehensive taxonomic revision of Engelhardia will provide an insight into understanding the plant diversity in tropical and subtropical Asia.

Opening a door to the spatiotemporal history of plants from the tropical Indochina Peninsula to subtropical China.

The complexity of global biodiversity in the tropical Indochina Peninsula and subtropical China bioregions has fascinated biologists for decades, but little is known about the spatiotemporal patterns in these regions. Accordingly, the aims of present study were to investigate the evolutionary and distribution patterns of Engelhardia in these regions and establish a model for examining biogeographic patterns and geological events throughout the tropical Indochina Peninsula and subtropical China. The effects of geological events occurring in the area between the Indochina Peninsula and subtropical China bioregions on the two trees species (i.e., E. roxburghiana and E. fenzelii) were evaluated. A robust phylogenetic framework of 884 individuals from 79 populations was used to generate time-calibrated cytoplasmic and nuclear phylogenetic frameworks based on cpDNA, nrDNA, and nSSR data, respectively. When considered along with ancestral area reconstructions, the genetic data were also used to assess and reconstruct the species' population genetic structure and diversity. These analyses yielded important information about the (1) historical distribution relationships between the tropical and subtropical flora of China; (2) effects of the East Asian summer monsoon (EASM) on the evolutionary history of Asia's plants; and (3) importance of biogeography in conservation planning. Although cytoplasmic-nuclear discordance indicated cpDNA and nrDNA were subject to distinct evolutionary mechanisms that reflected respective evolutionary histories of the plastid and nuclear genomes of prior demographic and biogeographic events. The tropical elements of Engelhardia occupied the Indochina Peninsula during the early Eocene, whereas the subtropical elements were transformed from the tropical elements during Miocene cooling and the onset of the EASM at the Oligocene-Miocene boundary, intensified during the late Miocene and Pliocene, facilitating the transformation of Engelhardia from the tropical Indochina Peninsula to subtropical China. Demographic history provided insights into prominent planning frameworks in conservation biology, namely that subtropical China functioned as a refugium during past climate oscillations and will continue to serve in this capacity in the future.

Shining a light on species delimitation in the tree genus Engelhardia Leschenault ex Blume (Juglandaceae).

Enhanced efficacy in species delimitation is critically important in biology given the pending biodiversity crisis under global warming and anthropogenic activity. In particular, delineation of traditional classifications in view of the complexity of species requires an integrative approach to effectively define species boundaries, and this is a major focus of systematic biology. Here, we explored species delimitation of Engelhardia in tropical and subtropical Asia. In total, 716 individuals in 71 populations were genotyped using five chloroplast regions, one nuclear DNA region (nrITS), and 11 nuclear simple sequence repeats (nSSR). Phylogenetic trees were constructed and relationships among species were assessed. Molecular analyses were then combined with 14 morphological characteristics of 720 specimens to further explore the species boundaries of Engelhardia. Integrating phylogenetic and morphological clusters provided well-resolved relationships to delineate seven species. The results suggested that: first, that E. fenzelii, E. roxburghiana, E. hainanensis, E. apoensis, and E. serrata are distinct species; second, E. spicata var. spicata, E. spicata var. aceriflora, E. spicata var. colebrookeana, and E. rigida should be combined under E. spicata and treated as a species complex; third, E. serrata var. cambodica should be raised to species level and named E. villosa. We illuminated that bias thresholds determining the cluster number for delimiting species boundaries were substantially reduced when morphological data were incorporated. Our results urge caution when using the concepts of subspecies and varieties in order to prevent confusion, particularly with respect to species delimitation for tropical and subtropical species. In some cases, re-ranking or combining subspecies and/or varieties may enable more accurate species delimitation.

Colocasia kachinensis, a new species of Araceae from Myanmar.

Colocasia kachinensis S.S. Zhou & J.T. Yin, is described and illustrated as a new species of Araceae from Kachin, Mynamar. The morphological characters are compared to those of other Colocasia species. Colocasia kachinensis is closely related to C. menglaensis J.T Yin, H. Li & Z.F. Xu, 2004, but differs from in having an erect stem, no stolons, smaller size, a different pattern of surface bristle distribution and male flowers 1-4-androus with stamens connate in truncate synandrium.

Notes on the genus Gastrochilus (Orchidaceae) in Myanmar.

Myanmar is known for its high species richness of genus Gastrochilus; however, most of them lack proper information for taxonomic revision. During four years of field investigation in Myanmar, two new distributional records were encountered, namely, G. arunachalensis and G. corymbosus and one species, i.e. G. pechei was rediscovered after its original description. The three species were not easy to interpret from the available original descriptions and types due to severely shrunk or poorly preserved specimens. Therefore, we hereby present more detailed illustrations and updated descriptions for these species, based on freshly collected materials.

A new species of Zingiber (Zingiberaceae) from Natma Taung National Park, Chin State, Myanmar.

Zingiber natmataungense S.S.Zhou & R.Li (Zingiberaceae), a new species from Natma Taung National Park, Chin State, Myanmar, is described and illustrated. The new species is morphologically similar to Z. yunnanense, but differs by: leaf blade abaxially light green, glabrous, ligule sparsely pubescent, ca. 2-3 mm, bracts glabrous; calyx white 20-21 × 3.2-3.5 mm, glabrous, apex obviously 3-toothed; corolla tube white, ca. 3.9-4.1 cm, labellum lateral lobes, ca. 1.5-1.7 × 0.6-0.7 cm; stamen with sparse pubescent, filament white, glabrous, 1-2 mm; anther connective appendage yellowish proximally, purplish distally; ovary white, sparsely white pubescent, epigynous glands, ca. 6-7 mm long, tapered, apex whorled, yellow. This new species is also similar to Z. teres, but has a different flower colour.

Ophiorrhiza monsvictoriae (Rubiaceae, Rubioideae), a new species from Myanmar.

A new species, Ophiorrhiza monsvictoriae S.S.Zhou & L.D.Duan, discovered at Natma Taung (Mt.Victoria) National Park, Chin State, Myanmar, is described and illustrated. The new species is morphologically similar to O. dulongensis, but differs from the latter by its stipules broadly triangular, 2-4 mm long, inflorescence axillary, 1-flowered, bracts lanceolate to subulate, 1-2 mm long, puberulous, calyx pilose, 1-2 mm long, lobes and tube equal length, corolla narrowly funnelform, 15 mm long, puberulous outside.

New contributions to the flora of Myanmar â .

In this study, we describe several new taxa belonging to the flora of Myanmar. One new family, Polyosmaceae (Polyosma wallichii Benn.) is recorded. Over ten new genera are recorded for the first time, including Amentotaxus Pilger (Taxaceae), Hydrobryopsis Engler (Podostemaceae), Cyrtosia Blume and Biermannia King & Pantling (Orchidaceae), Eleutharrhena Forman and Haematocarpus Miers (Menispermaceae), Craigia W.W. Smith & W.E. Evans (Malvaceae), Amblyanthopsis Mez (Primulaceae), Huodendron Rehder and Rehderodendron Hu (Styracaceae), Platea Blume (Metteniusaceae), Achyrospermum Blume (Lamiaceae), Christisonia Gardner (Orobanchaceae). In addition, five new species are described and illustrated: Tupistra natmataungensis Y.H. Tan & H.B. Ding, Biermannia burmanica Y.H. Tan & Bin Yang, Impatiens megacalyx Y.H. Tan & H.B. Ding, Amblyanthopsis burmanica Y.H. Tan & H.B. Ding, Platea kachinensis Y.H. Tan & H.B. Ding. The distribution, ecology, phenology, and conservation status of these new species are also described.

Coelogyne victoria-reginae (Orchidaceae, Epidendroideae, Arethuseae), a new species from Chin State, Myanmar.

Coelogyne victoria-reginae, a new species of section Proliferae, from Natma Taung (Mt.Victoria) National Park, Chin State, Myanmar, is described and illustrated. It is morphologically similar to C. prolifera, but the clustered pseudobulbs, pure brownish- red flowers and column wing with irregular notches at the apex of the new species differ from the other species. A preliminary risk-of-extinction assessment shows that the new species is regarded as EN C2a[i] according to the IUCN Red List Categories and Criteria.

Two new species of Trivalvaria (Annonaceae) from northern Myanmar.

Trivalvaria rubra and Trivalvaria casseabriae, two new species of Annonaceae from Putao, Kachin State, Myanmar, are here described and illustrated. They are morphologically similar to T. costata and T. macrophylla. The major differences between them are outlined and discussed. A diagnostic key to the species of Trivalvaria is provided.

Dendrobium naungmungense (Orchidaceae, Dendrobieae), a new species from Kachin State, Myanmar.

Dendrobium naungmungense, a new species from Naungmung, Kachin State, North Myanmar, is described and illustrated. It is morphologically similar to D. ciliatilabellum and D. vexabile, but the epichile is oblong with three long-ciliate laminae and the column wing has significant denticulation. A preliminary risk-of-extinction assessment shows that the new species should be regarded as Critically Endangered (CR) according to the IUCN Red List Categories and Criteria.

Aristolochia sinoburmanica (Aristolochiaceae), a new species from north Myanmar.

Aristolochia sinoburmanica Y.H.Tan & B.Yang, a new species of Aristolochiaceae from Putao, Kachin State, Myanmar, is described and illustrated. According to morphology (strongly curved perianth, 3-lobed limb, as well as 3-lobed gynostemium, anthers 6, adnate in 3 pairs to the base of gynostemium, opposite to the lobes), the species belongs to Aristolochia subgenus Siphisia. It is morphologically similar to A. faviogonzalezii, A. hainanensis, A. tonkinensis, A. saccata and A. xuanlienensis. The major differences between them are outlined and discussed. A detailed description, along with line drawings, photographs, habitat, distribution and conservation status, as well as a comparison to morphologically similar species, are also provided.

Hedychium putaoense (Zingiberaceae), a new species from Putao, Kachin State, Northern Myanmar.

Hedychium putaoense Y.H. Tan & H.B. Ding, a new species of Zingiberaceae from Putao, Kachin state, Northern Myanmar, is described and illustrated. It is similar to H. densiflorum Wall. and H. longipedunculatum A.R.K. Sastry & D.M. Verma, but differs by its very small bract (4-6 × 2.5-3 mm vs. 18-19 × 5-5.5 mm and ca. 11 × 7 mm, respectively), semicircle and dark red bracteole, orange flower and broadly falcate to lanceolate lateral staminodes.

Premna grandipaniculata (Lamiaceae, Premnoideae), a remarkable new species from north Myanmar.

A remarkable new Premna species from Myanmar, P. grandipaniculata Y.H.Tan & Bo Li (Lamiaceae), is here described and illustrated. It differs from all known congeneric taxa by having huge complicated panicles which have tertiary branches formed by spike-like thyrses. In Premna, such a spike-like thyrse is found in P. bracteata and P. interrupta, but those species can be easily distinguished from P. grandipaniculata by their habit, indumentum, leaf size and inflorescence structure.

Coelogyne magnifica (Orchidaceae), a new species from northern Myanmar.

Coelogyne magnifica (Orchidaceae), a new species from Putao, Kachin State, Myanmar, is described and illustrated. It belongs to Coelogyne section Ocellatae Pfitzer & Kraenzl. and it is morphologically similar to Coelogyne corymbosa and C. taronensis, but can be distinguished from these species by its larger flowers, lanceolate sepals and petals, a narrowly ovate lip, which has two bright yellow patches surrounded by shiny brownish red and two fimbriate or erose-lacerate lateral keels on the lip. The major differences between these species are outlined and discussed.