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The genus Paracladopus was established based on the type species P.chiangmaiensis in 2006. The two Paracladopus species are distributed in Thailand and Laos; however, neither of them has been documented in China to date. During our field work in 2020, we collected a river-weed in Wuzhi Mountain, Hainan Province of China. After checking the morphological characters, it was identified as P.chiangmaiensis. Then, we assembled and annotated its chloroplast genome based on the genome skimming data. The results showed that the complete chloroplast genome was 133,748 bp with 35% GC content, consisting of 76 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. A maximum-likelihood tree constructed based on the matk genes showed that WuMS109 was clustered with P.chiangmaiensis (AB537420, AB698348) without base difference and together with the remains of Paracladopus formed a sister clade to Cladopus. This is the first report of P.chiangmaiensis that represents a new generic record for China. The discovery of this river-weed could lay the foundation for investigating their biogeographical patterns and species evolution in further studies.The genus Paracladopus was established based on the type species P.chiangmaiensis in 2006. The two Paracladopus species are distributed in Thailand and Laos; however, neither of them has been documented in China to date. During our field work in 2020, we collected a river-weed in Wuzhi Mountain, Hainan Province of China. After checking the morphological characters, it was identified as P.chiangmaiensis. Then, we assembled and annotated its chloroplast genome based on the genome skimming data. The results showed that the complete chloroplast genome was 133,748 bp with 35% GC content, consisting of 76 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. A maximum-likelihood tree constructed based on the matk genes showed that WuMS109 was clustered with P.chiangmaiensis (AB537420, AB698348) without base difference and together with the remains of Paracladopus formed a sister clade to Cladopus. This is the first report of P.chiangmaiensis that represents a new generic record for China. The discovery of this river-weed could lay the foundation for investigating their biogeographical patterns and species evolution in further studies.

We describe , a new species of Podostemaceae from Yunxiao County, Fujian Province, China, based on morphological and molecular data and the genus is recorded here for the first time from China. has a gross morphology similar to , but it can be distinguished from the latter by its narrower roots, more numerous and longer leaves, shorter stigmas and more numerous ovules per locule. To distinguish the new species and study its phylogenetic position, its complete plastome was sequenced and characterised. The plastome is 132,110 bp in length, including a pair of inverted repeat regions (IRs) of 20,389 bp divided by the large single-copy (LSC) and small single-copy (SSC) regions of 79,022 bp and 12,310 bp, respectively. The plastome size of is relatively smaller compared to most angiosperms due to the absence of the 1 and 2 genes in the IR regions. The phylogenetic analyses also strongly support the separation of the new species from other taxa.

This paper introduces , a newly identified species that enriches our understanding of the diversity of the Podostemaceae in East Asia. Distinctive in its morphological traits, this species is characterized by the region's longest flowering shoots and exhibits a high number of elongated leaves per cluster, along with relatively slender roots. Phylogenetic analyses using Maximum Likelihood and Bayesian Inference methods on plastome and sequences confirm as a distinct species. It forms a clade with , its closest relative, together branching off from . The plastome of is 132,818 bp in length, comprising two inverted repeat regions of 20,881 bp, which are separated by large and small single-copy regions of 78,713 and 12,343 bp, respectively. Genetic analysis reveals the extensive loss of the and genes in the chloroplast genome, a trait common to the Podostemaceae, suggesting adaptations to environmental conditions or gene transfers to nuclear or mitochondrial genomes. This study improves the clarity of phylogenetic relationships in previous studies and underscores the importance of continued taxonomic and phylogenetic research.

Molecular data from Cladopus and Hydrobryum, members of the aquatic angiosperm family Podostemaceae, were analyzed phylogenetically using the chloroplast matK gene and internal transcribed spacer (ITS) regions of the nuclear ribosomal RNA (nrRNA) gene to infer the species relationships and the biogeographic history of the East Asian species. The phylogenies based on matK and ITS were incongruent for relationships in a northern clade of Cladopus, but the pattern of root morphologies (ribbon vs. linear) agreed with the matK phylogeny. The matK phylogeny revealed that all East Asian temperate species of each genus form a monophyletic group that is derived from tropical/subtropical species. A clock-constrained maximum-likelihood tree suggests that the divergence events of the temperate lineages from their tropical sisters occurred coevally in the two genera. Dispersal-vicariance analysis (DIVA) suggests that distribution at the middle latitudes was formed by a wide primary distribution covering tropical and temperate areas and a secondary dispersal event in Cladopus, and by a dispersal event in Hydrobryum. Two Kyushu-Fujian groups are found in Cladopus, one consisting of Japanese C. austro-osumiensis and Chinese C. fukiensis and another consisting of Japanese C. japonicus, C. austrosatsumensis, and C. doianus and Chinese C. chinensis, each of which shows little genetic differentiation between species from Kyushu, southern Japan, and Fujian, China, suggesting parallel biogeographic histories. Disjunct populations of Hydrobryum japonicum from Kyushu in southern Japan and from northern Thailand show little genetic differentiation, whereas a plant from Yunnan, China, diverged earlier than did the Japanese or Thai plants. The DIVA results suggest that the disjunctive distribution of Hydrobryum japonicum was formed by two dispersal events from Kyushu to Yunnan and to northern Thailand.

The new species X.X. Su, Miao Zhang & Bing-Hua Chen, from Fujian Province, China, is described and illustrated. It is similar to from Thailand, but differs in its two fertile stamens, fewer but longer vegetative ramuli, fewer but shorter flowering ramuli, shorter pedicels, capsule-stalk and stamens. The complete chroloplast genome of the new species is 129,074 bp long and has a typical quadripartite structure, including two inverted repeat regions (IRs) of 18,504 bp in length, separated by a large single-copy (LSC) and a small single-copy (SSC) regions of 79,000 bp and 13,066 bp, respectively. The 1 and 2 genes were lost compared to most higher plants, leading to a substantial reduction in the IR. The phylogenetic analysis using both and nrITS revealed that is sister to with moderate support, and formed a clade with other species, suggesting that the new species belongs to Tristichoideae.

[This corrects the article DOI: 10.3389/fpls.2019.01035.].[This corrects the article DOI: 10.3389/fpls.2019.01035.].

With the advent of next-generation sequencing technologies, whole-plastome data can be obtained as a byproduct of low-coverage sequencing of the plant genomic DNA. This provides an opportunity to study plastid evolution across groups, as well as testing phylogenetic relationships among taxa. Within the order Malpighiales (∼16,000 spp.), the Podostemaceae (∼300 spp.) stand out for their unique habit, living attached to rocks in fast-flowing aquatic habitats, and displaying highly modified morphologies that confound our understanding of their classification, biology, and evolution. In this study, we used genome skimming data to assemble the full plastid genome of 5 species within Podostemaceae. We analyzed our data in a comparative framework within Malpighiales to determine the structure, gene content, and rearrangements in the plastomes of the family. The Podostemaceae have one of the smallest plastid genomes reported so far for the Malpighiales, possibly due to variation in length of inverted repeat (IR) regions, gene loss, and intergenic region variation. We also detected a major inversion in the large single-copy region unique to the family. The uncommon loss or pseudogenization of and in angiosperms and in land plants in general is also found to be characteristic of Podostemaceae, but the compensatory mechanisms and implications of this and of the pseudogenization of , , and and loss of remain to be explained in this group. In addition, we estimated a phylogenetic tree among selected species in Malpighiales. Our findings indicate that the Podostemaceae are a distinct lineage with long branches that suggest faster rates of evolution in the plastome of the group, compared with other taxa in the order. This study lays the foundations for future phylogenomic studies in the family.

The clusioid clade of Malpighiales is comprised of five families: Bonnetiaceae, Calophyllaceae, Clusiaceae, Hypericaceae and Podostemaceae. Recent studies have found the plastome structure of Garcinia mangostana L. from Clusiaceae was conserved, while plastomes of five riverweed species from Podostemaceae showed significant structural variations. The diversification pattern of plastome structure of the clusioid clade worth a thorough investigation. Here we determined five complete plastomes representing four families of the clusioid clade. Our results found that the plastomes of the early diverged three families (Clusiaceae, Bonnetiaceae and Calophyllaceae) in the clusioid clade are relatively conserved, while the plastomes of the other two families show significant variations. The Inverted Repeat (IR) regions of Tristicha trifaria and Marathrum foeniculaceum (Podostemaceae) are greatly reduced following the loss of the ycf1 and ycf2 genes. An inversion over 50 kb spanning from trnK-UUU to rbcL in the LSC region is shared by Cratoxylum cochinchinense (Hypericaceae), T. trifaria and Ma. foeniculaceum (Podostemaceae). The large inversed colinear block in Hypericaceae and Podostemaceae contains all the genes in the 50-kb inversed colinear block in a clade of Papilionoideae, with two extra genes ( trnK-UUU and matK ) at one end. Another endpoint of both inversions in the two clusioids families and Papilionoideae is located between rbcL and accD . This study greatly helped to clarify the plastome evolution in the clusioid clade.

Dalzellia ubonensis M. Kato (2006), previously known only from Laos, Thailand, and Vietnam, is reported here for the first time from India, specifically from the Kallar River in the Vadasserikkara Range, Pathanamthitta district, Kerala. Detailed morphological examination revealed key diagnostic traits—absence of roots, broad crustose shoots, rosette leaf arrangement, and numerous ovules—that match the protologue of D. ubonensis and distinguish it from other Indian congeners, particularly Dalzellia gracilis. For molecular confirmation, genomic DNA was extracted and the plastid matK region was amplified and sequenced. BLASTn analysis showed ≥98% sequence identity and 100% query coverage with reference Dalzellia sequences in GenBank, corroborating its identity as D. ubonensis. This integrative taxonomic approach—combining classical morphological taxonomy with DNA barcoding—confirms a significant range extension for the species and represents the first verified record of D. ubonensis in India. This finding highlights the floristic uniqueness of Kerala’s riverine ecosystems and underscores the need for targeted exploration and conservation of aquatic Podostemaceae taxa in understudied regions of the Western Ghats.

PREMISE OF THE STUDY: The clusioid clade (Malpighiales) has an ancient fossil record (~90 Ma) and extant representatives exhibit a pantropical distribution represented on all former Gondwanan landmasses (Africa, Australia, India, Madagascar, and South America) except Antarctica. Several biogeographers have hypothesized that the clusioid distribution is an example of Gondwanan vicariance. Our aim is to test the hypothesis that the modern distribution of the clusioid clade is largely explained by Gondwanan fragmentation. METHODS: Using a four gene, 207-taxon data set we simultaneously estimated the phylogeny and divergence times of the clusioid clade using a Bayesian Markov chain Monte Carlo approach. Ancestral Area Reconstructions (AARs) were then conducted on a distribution of 1000 trees and summarized on a reduced phylogeny. KEY RESULTS: Divergence time estimates and AARs revealed only two or four cladogenic events that are potentially consistent with Gondwanan vicariance, depending on the placement of the ancient fossil Paleoclusia. In contrast, dispersal occurred on > 25% of the branches, indicating the current distribution of the clade likely reflects extensive recent dispersal during the Cenozoic (< 65 Ma), most of which occurred after the beginning of the Eocene (~56 Ma). CONCLUSIONS: These results support growing evidence that suggests many traditionally recognized angiosperm clades (families and genera) are too young for their distributions to have been influenced strictly by Gondwanan fragmentation. Instead, it appears that corridors of dispersal may be the best explanation for numerous angiosperm clades with Gondwanan distributions.