Cololejeunea metzgeriopsis, a new species record for Thailand

Cololejeunea metzgeriopsis (K. I. Goebel) Gradst. et al., a neotenic liverwort, was newly discovered in lowland evergreen forest, southern Thailand. A description and illustrations of Thai plants are provided

Thysananthus ciliaris (Lejeuneaceae, Marchantiophyta): a new record of Thysananthus species for Thailand

Thysananthus ciliaris (Sande Lac.) Sukkharak, a rare species from Sumatra and Peninsular Malaysia, was newly discovered in lowland evergreen forest, southern Thailand. A detailed description and illustrations are here provided

The genus Colura section Glotta (Lejeuneaceae, Marchantiophyta) in Thailand

The genus Colura (Dumort.) Dumort. sect. Glotta Grolle et R. L. Zhu in Thailand is studied based on herbarium specimens and especially on recent collections. The section is reported from Thailand for the first time. Two species are recognized, namely C. bisvoluta Herzog et Jovet-Ast and C. karstenii K. I. Goebel. Descriptions, illustrations, and a key to species are provided

Liverworts show a globally consistent mid‐elevation richness peak

The study of elevational gradients allows to draw conclusions on the factors and mechanisms determining patterns in species richness distribution. Several earlier studies investigated liverwort diversity on single or few elevational transects. However, a comprehensive survey of the elevational distribution patterns of liverwort richness and their underlying factors is lacking so far. This study's purpose was to fill this gap by compiling an extensive data set of liverwort elevational patterns encompassing a broad diversity of mountains and mountain ranges around the world. Using polynomial regression analyses, we found a prevalence of hump‐shaped richness patterns (19 of 25 gradients), where liverwort species richness peaked at mid‐elevation and decreased towards both ends of the gradient. Against our expectation and unlike in other plant groups, in liverworts, this pattern also applies to elevational gradients at mid‐latitudes in temperate climates. Indeed, relative elevation, calculated as the percentage of the elevational range potentially inhabited by liverworts, was the most powerful predictor for the distribution of liverwort species richness. We conclude from these results that the admixture of low‐ and high‐elevation liverwort floras, in combination with steep ecological gradients, leads to a mid‐elevation floristic turnover shaping elevational patterns of liverwort diversity. Our analyses further detected significant effects of climatic variables (temperature of the warmest month, potential evapotranspiration, and precipitation of the warmest month) in explaining elevational liverwort richness patterns. This indicates that montane liverwort diversity is restricted by high temperatures and subsequent low water availability especially towards lower elevations, which presumably will lead to serious effects by temperature shifts associated with global warming

Phaeoceros perpusillus var. scabrellus (Notothyladaceae, Anthocerotophyta), a new taxon from northern Thailand

A new variety of hornwort from northern Thailand, Phaeoceros perpusillus var. scabrellus is described based on morphological characters and molecular phylogenetic analyses. In this study, phylogenetic analyses supported that the new variety is closely related to P. perpusillus var. perpusillus. Morphologically, it is distinguished from the autonimic variety in nearly smooth spores under light microscope. A taxonomic description, illustrations, and light and scanning electron micrographs are provided. In addition, the new variety is assessed as Endangered (EN), demonstrating its rarity by being currently known from only three subpopulations

Comparative analysis of plastid genomes in the non-photosynthetic genus Thismia reveals ongoing gene set reduction

Heterotrophic plants provide intriguing examples of reductive evolution. This is especially evident in the reduction of their plastid genomes, which can potentially proceed toward complete genome loss. Several milestones at the beginning of this path of degradation have been described; however, little is known about the latest stages of plastome reduction. Here we analyze a diversity of plastid genomes in a set of closely related non-photosynthetic plants. We demonstrate how a gradual loss of genes shapes the miniaturized plastomes of these plants. The subject of our study, the genus Thismia, represents the mycoheterotrophic monocot family Thismiaceae, a group that may have experienced a very ancient (60–80 mya) transition to heterotrophy. In all 18 species examined, the plastome is reduced to 14–18 kb and is highly AT-biased. The most complete observed gene set includes accD, seven ribosomal protein genes, three rRNA, and two tRNA genes. Different clades of Thismia have undergone further gene loss (complete absence or pseudogenization) compared to this set: in particular, we report two independent losses of rps2 and rps18

Aphyllorchis periactinantha (Orchidaceae, Neottieae), a new mycoheterotrophic species from peninsular Thailand

A new orchid species from southern Thailand, Aphyllorchis periactinantha, is described and illustrated. The novelty is characterized by the subactinomophic flowers, the concave labellum, not divided into hypochile and epichile, the reduced staminodes, the shallowly bilobed stigma and the semicircular rostellum. A key to the species of Aphyllorchis in Thailand is updated

Aphyllorchis periactinantha (Orchidaceae, Neottieae), a new mycoheterotrophic species from peninsular Thailand

A new orchid species from southern Thailand, Aphyllorchis periactinantha, is described and illustrated. The novelty is characterized by the subactinomophic flowers, the concave labellum, not divided into hypochile and epichile, the reduced staminodes, the shallowly bilobed stigma and the semicircular rostellum. A key to the species of Aphyllorchis in Thailand is updated

Bryophyte Studies in Thailand: Past, Present, and Future

The historical development of bryophyte studies in Thailand is reviewed. Two historical periods are distinguished: the first period, 1899-1977, during which collections were made and studies were carried out by foreign botanists/bryologists in the framework of expeditions and the Flora of Thailand project; and the second one, 1977 to the present day, in which bryophyte work has been done mainly by Thai bryologists. In total, two species of hornworts, 20 of liverworts, and 63 of mosses have been described as new to science based on collections from Thailand. Of these, 48 are hitherto only known from Thailand and may be considered endemic to the country. Future work should focus more on taxonomic treatments of individual genera although further area-based research is also necessary.</p

Taxonomic Studies on Thai Anthocerotophyta I. The Genera Dendroceros and Megaceros (Dendrocerotaceae)

A taxonomic review of the hornwort genera Dendroceros Nees and Megaceros Campb. in Thailand is presented, based on herbarium specimens and field surveys. Three species are recognized, namely D. cucullatus Steph., D. suplanus Steph. and M. flagellaris (Mitt.) Steph. A key, descriptions and line drawings and notes on the ecology and geographical distribution of the species are provided