Ten new species of the genus Didymocarpus are described from Thailand: Didymocarpus alboroseus, D. flaviflorus Nangngam, D. hongsonensis Nangngam, D. kiewbangii, D. kwanjaiae, D. mekongensis, D. niveus, D. phuwuaensis, D. suchartii Nangngam and D. vilaiwaniae. Full descriptions, distributions, ecology and colour plates are provided for all taxa. These additional new species increase the total number of Didymocarpus in Thailand to thirty-five species, and therefore, a key to the species of Didymocarpus in Thailand is also provided in this paper.

This study presents a classical taxonomic approach to parts of Dendrobium sect. Pedilonum, focusing on a newly discovered species from Thailand and the D. cumulatum s.l. species complex. The new species, D. nakhonsiense seems endemic to Nakhon Si Thammarat Province in Peninsular Thailand where it is only known from one location. It is morphologically close to D. cowenii but is distinguished by its slightly larger flowers with a relatively longer, obtuse to rounded mentum and by its differently shaped dorsal sepal and labellum lamina. The D. cumulatum s.l. complex includes four taxa, viz. D. cumulatum, D. rhodocentrum, D. eoum, and D. calicopis. Based on extensive herbarium studies and morphological comparisons, we propose the recognition of two distinct species: D. cumulatum (syn.: D. rhodocentrum, D. calicopis) and D. eoum. Our findings contribute to the understanding of species diversity and distribution within Dendrobium sect. Pedilonum.

IntroductionThe terrestrial orchid genus Nervilia is diagnosed by its hysteranthous pattern of emergence but is nested among leafless myco-heterotrophic lineages in the lower Epidendroideae. Comprising ca. 80 species distributed across Africa, Asia and Oceania, the genus remains poorly known and plagued by vague and overlapping species circumscriptions, especially within each of a series of taxonomically intractable species complexes. Prior small-scale, exploratory molecular phylogenetic analyses have revealed the existence of cryptic species, but little is otherwise understood of origin, the scale and timing of its biogeographic spread, or the palaeoclimatic factors that have shaped its ecology and given rise to contemporary patterns of occurrence.MethodsHere, we sample widely throughout the generic range, including 45 named taxa and multiple accessions referable to several widespread ‘macrospecies’, as well as material of equivocal identity and probable undescribed status, for the first time enabling an evaluation of taxonomic boundaries at both species and sectional level. Using nuclear (ITS) and plastid (matK, trnL-F) sequence data, we conduct phylogenetic (maximum parsimony and Bayesian inference) and ancestral area analysis to infer relationships and resolve probable origin and colonisation routes.ResultsThe genus is strongly supported as monophyletic, as are each of its three sections. However, the number of flowers in the inflorescence and other floral characters are poor indicators of sectional affinity. Dated ancestral area analysis supports an origin in Africa in the Early Oligocene, with spread eastwards to Asia occurring in the Late Miocene, plausibly via the Gomphotherium land bridge at a time when it supported woodland and savanna ecosystems.DiscussionTaxonomic radiation in Asia within the last 8 million years ties in with dramatic Himalayan-Tibetan Plateau uplift and associated intensification of the Asia monsoon. Multiple long-range migrations appear to have occurred thereafter, as the genus colonised Malesia and Oceania from the Pliocene onwards. The bulk of contemporary species diversity is relatively recent, potentially explaining the ubiquity of cryptic speciation, which leaves numerous species overlooked and unnamed. Widespread disjunct species pairs hint at high mobility across continents, extinction and a history of climate-induced vicariance. Persistent taxonomic challenges are highlighted.

Somnuekia is described as a new genus of Malvaceae, currently known only from a few locations in the upper part of Tenasserim in northern and peninsular Thailand. Morphological and molecular phylogenetic analyses, based on plastid DNA sequence regions, support the recognition of this new genus within the Brownlowioideae (Malvaceae). Its distinct phylogenetic position, along with a distinct set of morphological and palynological characteristics, strongly support the recognition of Somnuekia as a new genus. A formal description of Somnuekia flaviflora is provided along with illustrations, photographs, a distribution map and conservation notes. Furthermore, this new genus is compared to other Asian genera within the subfamily.

Somnuekia is described as a new genus of Malvaceae, currently known only from a few locations in the upper part of Tenasserim in northern and peninsular Thailand. Morphological and molecular phylogenetic analyses, based on plastid DNA sequence regions, support the recognition of this new genus within the Brownlowioideae (Malvaceae). Its distinct phylogenetic position, along with a distinct set of morphological and palynological characteristics, strongly support the recognition of Somnuekia as a new genus. A formal description of Somnuekia flaviflora is provided along with illustrations, photographs, a distribution map and conservation notes. Furthermore, this new genus is compared to other Asian genera within the subfamily.

The new species Chayamaritia sirindhorniana (Gesneriaceae) is described from materials collected in Loei Province in Northeastern Thailand. As it is currently only known from the type locality, further exploration of the region is needed to assess its conservation status.

Sophora phulangkaensis is illustrated and newly described here. The species shows similarities with its congener, S. exigua, by having an obovate terminal leaf let and up to 15 leaflets but differs in the floralparts. A morphological comparison between the two species is provided along with a discussion. The phylogenetic place- ment of then ewspecies is presented and discussed based on molecular evidence by nuclear (ITS) and chloroplast markers (matK). The results suggest that the new species is nested into sect. Rubriflorae, which includes S. exigua and S. huamotensis. The circumscription of sect. Rubriflorae is expanded after being redefined by our findings. In addition, the updated key to species of the genus Sophora for the Flora of Thailand is given based on recent specimen observations. Additionally, lectotypes for S. exigua, S. tonkinensis, and S. violacea var. pilosa are designated.

Four new species of Microchirita (Gesneriaceae) from Thailand are described: Microchirita orothaiae, M. puglisiae, M. radiata and M. simia. With the addition of these species, 41 species are now recorded for Thailand.

Eleven species of Thrixspermum are newly recorded from Thailand. Four belong to sect. Thrixspermum: T. crassilabre (South-Western floristic region), T. lampongense (Eastern floristic region), T. latisaccatum (Peninsular), and T. tortum (Peninsular); and seven to sect. Dendrocolla: T. anceps (Peninsular), T. bromeliforme (of unknown provenance), T. duplocallosum (Peninsular), T. merapohense (Peninsular), T. pardale (Peninsular), T. patkaiense (Eastern), and T. pulchellum (Peninsular). Descriptions, photographs, and notes on distribution, ecology, phenology, vernacular names, and recognition are provided. Three names are lectotypified. Five species are considered to be uncommon in the wild: T. anceps, T. crassilabre, T. duplocallosum, T. patkaiense, T. tortum; and T. bromeliforme is known from cultivation and suspected to originate in Krabi Province, Peninsular Thailand.

Garcinia minutiflora (Clusiaceae), previously known only from Peninsular Malaysia, is reported as a new record from dry evergreen forest on limestone hills in Phangnga and Krabi Provinces, Peninsular Thailand. A detailed morphological description, illustrations and a distribution map of the species are presented, along with information on distribution, specimens examined, habitat, conservation assessment, phenology and vernacular name. In addition, G. minutiflora is lectotypified.

A new species of Dendrobium sect. Crinifera is described from Thailand. The late Peter O’Byrne is appropriately credited for his important preparatory work for our study and for coining the name of the new species, D. krabiense. Apparently endemic to southern Thailand, D. krabiense is similar to D. pardalinum but differs in the lip mid-lobe being distinctly clawed and in the lip ornaments only consisting of two lateral keels that extend from near lip base to claw of mid-lobe. Dendrobium krabiense is also similar to D. phuketense but differs in having larger, spotted flowers with a proportionally longer mentum. The material here referred to D. krabiense was previously misidentified as Flickingeria pallens (now considered a synonym of D. pardalinum).

Introduction Plants confined to island-like habitats are hypothesised to possess a suite of functional traits that promote on-spot persistence and recruitment, but this may come at the cost of broad-based colonising potential. Ecological functions that define this island syndrome are expected to generate a characteristic genetic signature. Here we examine genetic structuring in the orchid Phalaenopsis pulcherrima , a specialist lithophyte of tropical Asian inselbergs, both at the scale of individual outcrops and across much of its range in Indochina and on Hainan Island, to infer patterns of gene flow in the context of an exploration of island syndrome traits. Methods We sampled 323 individuals occurring in 20 populations on 15 widely scattered inselbergs, and quantified genetic diversity, isolation-by-distance and genetic structuring using 14 microsatellite markers. To incorporate a temporal dimension, we inferred historical demography and estimated direction of gene flow using Bayesian approaches. Results We uncovered high genotypic diversity, high heterozygosity and low rates of inbreeding, as well as strong evidence for the occurrence of two genetic clusters, one comprising the populations of Hainan Island and the other those of mainland Indochina. Connectivity was greater within, rather than between the two clusters, with the former unequivocally supported as ancestral. Discussion Despite a strong capacity for on-spot persistence conferred by clonality, incomplete self-sterility and an ability to utilize multiple magnet species for pollination, our data reveal that P. pulcherrima also possesses traits that promote landscape-scale gene flow, including deceptive pollination and wind-borne seed dispersal, generating an ecological profile that neither fully conforms to, nor fully contradicts, a putative island syndrome. A terrestrial matrix is shown to be significantly more permeable than open water, with the direction of historic gene flow indicating that island populations can serve as refugia for postglacial colonisation of continental landmasses by effective dispersers.

Garcinia exigua (Clusiaceae), previously known from Borneo [Malaysia (Sarawak) and Brunei], is reported as a new record from dry evergreen forest on limestone hill in Krabi Province, Peninsular Thailand. A detailed morphological description, illustrations and a distribution map of the species are provided, along with information on distribution, specimens examined, habitat, conservation status, phenology, etymology and vernacular name.

Five new species of Thrixspermum (Orchidaceae) are described from Thailand, two from sect. Dendrocolla: T. alboluteum (South-West floristic region), T. praetermissum (East); and three from sect. Thrixspermum: T. simile (South-East), T. flammeum (East), T. polystictum (East). Descriptions, illustrations, notes on distribution, ecology, phenology, conservation status, and morphological comparisons with allied species are provided. Thrixspermum musciflorum and its variety nilagiricum are reduced to the synonymy of T. formosanum. Thrixspermum album is reduced to the synonymy of T. pulchellum. We select a lectotype and an epitype for T. trichoglottis (Hook.f.) Kuntze and provide a detailed description of this common but so far incompletely known species.

Three new species of the genus Millettia; M. calcicola Mattapha, G.P.Lewis & Hawkins, M. fulva Mattapha, F.Forest & Hawkins and M. khaoyaiensis Mattapha, Schrire & Suddee, are described and illustrated. Key diagnostic characters of these species are discussed.

Ehretia pranomiana sp. nov. is illustrated and described from northern and south‐western Thailand. The new species is similar to E. macrophylla and E. acuminata by having elliptic leaves with a serrate margin, but can be distinguished by being a scrambling shrub with densely hispid leaf blades, corymbose inflorescence with 4–10 flowers, corolla with erect lobes and calyx longer than fruit at maturity. An updated identification key to the species of Ehretia known from Thailand is provided.

Eight new species of Microchirita (Gesneriaceae) from Thailand are described: Microchirita candida, M. chonburiensis, M. formosa, M. fuscifaucia, M. poomae, M. rayongensis, M. striata and M. suwatii. With the addition of these species, 37 species are now recorded for Thailand, considerably more than any other country.

Taeniophyllum rudolfii, previously known only from New Caledonia, was newly discovered in lower montane forest in southern Thailand. A description, line drawings and photographs are provided. In addition, a lectotype is also designated here.

Abstract. Saisorn W, Suddee S. 2023. Seed micromorphology of tribe Desmodieae (subfamily Papilionoideae, family Leguminosae) from Thailand with its taxonomic implications. Biodiversitas 24: 5572-5585. The seed micromorphology of 21 genera and 58 species of the tribe Desmodieae in Thailand was studied. The result showed that the shape of the seed can be ellipsoid or transversely ellipsoid, irregular, oblongoid, quadrangular, rectangular, reniform, rhomboid, subcircular, and triangular. An oblongoid shape is restricted to the genus Sohmaea; the seeds’ length, width, and thickness are 0.94-5.93 mm, 0.78-3.65 mm, and 0.39-1.92 mm, respectively. The testa color can be light green to green, yellow, light to dark brown, or black. Testa patterns can be classified into nine types: colliculate, colliculate-rugulate, fissured, pitted, reticulate, reticulate-reticulate, reticulate-rugulate, rugulate, and smooth. The rim-arillate aril can be thin, thick, or well-developed. This tribe is classified into three groups based on aril types. Group I: a thin rim-arillate type is restricted to Akschindlium godefroyanum. Group II: a thick rim-arillate type is found on the seeds of the most studied plants. Group III: a well-developed rim-arillate type is a taxonomic characteristic of Codariocalyx. The overall shape of the rim-arillate aril is subcircular, circular, subcircular-elliptic, elliptic, elliptic-oblong, and oblong. An oblong shape of the rim-arillate aril is a unique character for Grona heterophylla compared to other species within Grona.

Diospyros bambuseti is a rare species endemic to Thailand that was previously known only from type specimens. The only male specimens of this species were collected in 1930 from a bamboo forest in Aranya Prathet district, now Sa Kaeo Province, Thailand. Both male and female plants were rediscovered in Surat Thani Province, upper Peninsular Thailand during 2015–2020. In this work, we provide an emended description, detailed ecological data, photographs, and illustrations of recently collected specimens. We performed lectotypification and investigated the phylogenetic placement and sister taxa of D. bambuseti based on the DNA sequences of eight plastid regions. D. bambuseti is closely related to D. ehretioides, D. fasiculosa, and D. venosa. Finally, we provide a detailed morphological comparison of D. bambuseti with related species.