Patterns of floristic inventory and plant collections in Myanmar.

Myanmar is one of the most biodiverse countries in the Asia-Pacific region due to a wide range of climatic and environmental heterogeneity. Floristic diversity in Myanmar is largely unknown, resulting in a lack of comprehensive conservation plans. We developed a database of higher plants in Myanmar derived from herbarium specimens and literature sources, and analyzed patterns of diversity inventories and collection inconsistencies, aiming to provide a baseline floristic data of Myanmar and act as a guide for future research efforts. We collected 1,329,354 records of 16,218 taxa. Results show that the collection densities at the township level was variable, with 5% of townships having no floristic collections. No ecoregion had an average collection density of greater than 1 specimen/km2 and the lowest collection density was found in the Kayah-Karen Montane Rainforests, which covered 8% of Myanmar's total area. The highest sampling densities were found in Mandalay Region, Chin State, and Yangon Region. Despite floristic collections over the past three centuries, knowledge of the distribution of the vast majority of plant taxa remained limited, particularly for gymnosperms, pteridophytes, and bryophytes. More botanical surveys and further analyses are needed to better describe Myanmar's floristic diversity. An important strategy to promote knowledge of the biodiversity patterns in Myanmar is to improve the collection and digitalization of specimens and to strengthen cooperation among countries.

Corrigendum to Patterns of floristic inventory and plant collections in Myanmar [Plant Divers. 45 (3) (2023) 302-308].

[This corrects the article DOI: 10.1016/j.pld.2023.01.008.].

Plastid genome evolution of a monophyletic group in the subtribe Lauriineae (Laureae, Lauraceae).

Litsea, a non-monophyletic group of the tribe Laureae (Lauraceae), plays important roles in the tropical and subtropical forests of Asia, Australia, Central and North America, and the islands of the Pacific. However, intergeneric relationships between Litsea and Laurus, Lindera, Parasassafras and Sinosassafras of the tribe Laureae remain unresolved. In this study, we present phylogenetic analyses of seven newly sequenced Litsea plastomes, together with 47 Laureae plastomes obtained from public databases, representing six genera of the Laureae. Our results highlight two highly supported monophyletic groups of Litsea taxa. One is composed of 16 Litsea taxa and two Lindera taxa. The 18 plastomes of these taxa were further compared for their gene structure, codon usage, contraction and expansion of inverted repeats, sequence repeats, divergence hotspots, and gene evolution. The complete plastome size of newly sequenced taxa varied between 152,377 bp (Litsea auriculata) and 154,117 bp (Litsea pierrei). Seven of the 16 Litsea plastomes have a pair of insertions in the IRa (trnL-trnH) and IRb (ycf2) regions. The 18 plastomes of Litsea and Lindera taxa exhibit similar gene features, codon usage, oligonucleotide repeats, and inverted repeat dynamics. The codons with the highest frequency among these taxa favored A/T endings and each of these plastomes had nine divergence hotspots, which are located in the same regions. We also identified six protein coding genes (accD, ndhJ, rbcL, rpoC2, ycf1 and ycf2) under positive selection in Litsea; these genes may play important roles in adaptation of Litsea species to various environments.

Thylacopterisminuta (Polypodiaceae), a new fern species from Myanmar.

The genus Thylacopteris is a small, phylogenetically isolated genus belonging to the fern family Polypodiaceae. This study describes a new species, Thylacopterisminuta, based on collections obtained during field surveys of Shan State, Myanmar. This new species is distinct from other species of Thylacopteris in its small size and presence of sclerenchyma strands in the rhizome. This species is also distinct from the only other species of Thylacopteris with molecular data available, T.papillosa, in a plastid rbcL phylogeny of Polypodiaceae. This new discovery of Thylacopteris from Myanmar suggests that this genus is still overlooked in Southeast Asia.

Lepisorusmedioximus (Polypodiales, Polypodiaceae), a new species from Shan State of Myanmar.

A new species of the species-rich fern genus Lepisorus (Polypodiales, Polypodiaceae) has been found to occur in Shan state, Myanmar. Lepisorusmedioximus is described based on morphological characters and phylogenetic evidence. Phylogenetic analyses showed that the specimens of L.medioximus formed a distinct clade nested in the Pseudovittaria clade. The morphological comparison demonstrated that the species is distinct from phylogenetically related species, namely L.elegans, L.contortus, and L.tosaensis, in the morphology of the rhizome scales, size, and shape of the lamina, position of sori, and paraphyses.

Data on pteridophyte species diversity and status of the International Union for Conservation of Nature in each political unit of Myanmar.

The data in this article provide information about the species richness of each political unit in Myanmar and their preliminary conservation status. The dataset was compiled by gathering scattered data from different sources. The majority of the data were compiled from the authors' collections and historical and recent floristic treatments. Online databases and herbarium specimens were additional resources used for data compilation. In total, 603 species were documented and species names were standardized in accordance with the International Plant Names Index and Pteridophyte Phylogeny Group. Species composition between political units was calculated using the minimum variance of the Jaccard's dissimilarity matrix. Conservation status for 558 pteridophyte species from Myanmar was evaluated based on the global occurrences and occurrences only in Myanmar, and species with less than three occurrences were excluded from the analysis. This dataset can be applied as the reference data for future taxonomic revisions, biodiversity assessments, and conservation planning. Moreover, the data can be used for global diversity assessment, broad-scale species distribution modeling and bioclimatic modeling. The data provided in this manuscript have been analyzed and discussed in Khine and Schneider [1].

Correction to: Towards the conservation of the Mesozoic relict fern Christensenia: a fern species with extremely small populations in China.

In the original publication of the article, one of the author names, "Tao Fuijwara" was published incorrectly. The correct name is Tao Fujiwara.

Towards the conservation of the Mesozoic relict fern Christensenia: a fern species with extremely small populations in China.

The Chinese occurrences of the marattioid fern genus Christensenia have been considered as requiring protection because of its extreme rarity and very small population size. Here, we explored different biological aspects to enable protection of these rare ferns, well known as Mesozoic living fossils. Firstly, we documented the cytology of the Chinese occurrences for the first time. This is the second tetraploid record of Christensenia worth for further studies to confirm its taxonomic status. Secondly, we obtained the first complete plastid genome of this genus, which confirmed the proposed conservatism of the plastid genome structure in marattioid ferns. By comparing the chloroplast genome with other marattioids, we identified several candidate regions to develop highly variable markers to investigate the intra-species diversity of marattioid ferns. Thirdly, phylogenetic analyses of rbcL sequences implied that there are at least two distinct species of Christensenia. Finally, we re-assessed the conservation status of Christensenia in the context of its local and global distribution by assessing specimen information extracted from publications and digitized voucher information. This assessment confirmed the need to obtain more accurate information about the distribution of this genus to assess the status incorporating the disjunct distribution from southern China and India in the North towards the Solomon Islands in the South.

Selliguea kachinensis (Polypodiaceae), a new fern species of uncertain affinity from Northern Myanmar.

We describe Selliguea kachinensis as a new species from Northern Myanmar and discuss its generic placement in either Selliguea or Arthromeris. The conservation status is assessed as Data Deficient. In addition, we make the new combination Selliguea erythrocarpa (Mett. ex Kuhn) Hovenkamp, S. Linds., Fraser-Jenk.