Aristolochiaceae, comprising about 600 species, is a unique plant family containing aristolochic acids (AAs). In this study, we sequenced seven species of Aristolochia, and retrieved eleven chloroplast (cp) genomes published for comparative genomics analysis and phylogenetic constructions. The results show that the cp genomes had a typical quadripartite structure with conserved genome arrangement and moderate divergence. The cp genomes range from 159,308 bp to 160,520 bp in length and have a similar GC content of 38.5%–38.9%. A total number of 113 genes were identified, including 79 protein-coding genes, 30 tRNAs and four rRNAs. Although genomic structure and size were highly conserved, the IR-SC boundary regions were variable between these seven cp genomes. The trnH-GUG genes, are one of major differences between the plastomes of the two subgenera Siphisia and Aristolochia. We analyzed the features of nucleotide substitutions, distribution of repeat sequences and simple sequences repeats (SSRs), positive selections in the cp genomes, and identified 16 hotspot regions for genomes divergence that could be utilized as potential markers for phylogeny reconstruction. Phylogenetic relationships of the family Aristolochiaceae inferred from the 18 cp genome sequences were consistent and robust, using maximum parsimony (MP), maximum likelihood (ML), and Bayesian analysis (BI) methods.
Aristolochia subgen. Siphisia, comprising 98 species, is mainly distributed in East and South Asia, with some scattered in North and Central America. It has often been recognized as one of three subgenera of Aristolochia and can be distinguished from both remaining subgenera (Aristolochia subgen. Aristolochia and Aristolochia subgen. Pararistolochia) by morphological synapomorphies such as a strongly curved perianth with a 3-lobed limb, and especially the 3-lobed gynostemium, anthers paired on the outer surface of each gynostemium segment. However, recent cladistic analyses based on morphological characters and molecular data suggested that Aristolochia s.l. should be divided into four genera in two subtribes. In this study, a comprehensive analysis of molecular data of two plastid genic spacers (rps16-trnK and petB-petD), and two nuclear genes (phyA and ITS2) with an extensive sampling of Asian and American species was conducted. The combined datasets confirmed that Aristolochia subgen. Siphisia should be treated as an independent genus. Then Isotrema is reinstated here with 87 new combinations for the most comprehensive enumeration.
The infrageneric classification of Ficus (Moraceae) has raised concerns since Berg put forward his six subgenera system. Molecular analyses have revealed some unnatural groups within this system. The status of F. subg. Synoecia and the relationships between this subgenus and its allies are among the major challenges facing classification within the genus. To resolve these problems, we reconstructed the phylogenetic trees with three nuclear markers from 147 ingroup taxa (including approximately half of F. subg. Synoecia species and three‐fifths of F. subg. Ficus) and implemented ancestral area and life‐form reconstructions to trace the evolutionary history. Results showed that F. subg. Synoecia and F. subg. Ficus (except F. subsect. Ficus) constituted a well‐supported monophylum, which is sister to F. subg. Terega. This monophylum comprises two clades: one clade covers F. subsect. Frutescentiae of F. sect. Ficus and F. subsect. Plagiostigma of F. sect. Pogonotrophe, and the other covers F. sect. Eriosycea, F. sect. Apiosycea and the rest of F. sect. Pogonotrophe. Ancestral area reconstruction revealed that the first clade has a distinct origin in East Asia, but the second one shows fewer obvious signs. Ancestral life‐form reconstruction suggested that the climbing habit, a key trait used to divide F. subg. Ficus and F. subg. Synoecia, has evolved independently more than four times, rendering it an unsuitable characteristic to circumscribe the subgenera. Thus, we merged F. subg. Synoecia and F. subg. Ficus (excluding F. subsect. Ficus) into one subgenus, containing two newly delimited sections and six new synonyms.
From 2000 to 2019, 11,895 new names or new additions to the Chinese vascular flora were proposed by 4226 individuals (4086 articles and 140 books), as documented in the Chinese Plant Names Index (CPNI). During those 20 years, 4407 new taxa of vascular plants were described from China, including 7 new families, 132 new genera, 3543 new species, 68 new subspecies, 497 new varieties and 160 new forms. Additionally, 3562 new combinations and names at new rank and 306 new replacement names were also proposed. Among these various new names were 150 invalid names and 108 illegitimate names, including some that have not been resolved. Six hundred and forty three vascular plants were reported as new to China, while 2349 names were reduced to synonyms of 1406 taxa. The data show that the Chinese flora increased in size at the rate of about 200 taxa annually during those years. Despite the increased attention given to biodiversity in recent years, the evidence indicates that a large number of species in China have yet to be discovered. Further basic investigation of the Chinese flora is needed. Additionally, in the past two decades only 8.5% of the newly published species have been based on molecular evidence, but in the past five years such data have increased significantly, reaching about 20%. Molecular data will undoubtedly become increasingly significant in the discovery of new species in the coming years. Yunnan, Guangxi, Sichuan, Xizang and Taiwan were important sources of new discoveries, with more than 3300 new taxa and records from these five provinces. By area, Taiwan and Hainan, two islands in southern China, have the highest density of newly discovered species. Regional plant surveys are still needed, especially in areas in the southwest and on the southern islands.
Aristolochia pseudoutriformis X.X.Zhu & J.S.Ma, sp. nov. and A. yangii X.X.Zhu & J.S.Ma, sp. nov., two new species from Yunnan, China, are described and illustrated here. The former is morphologically similar to A. utriformis and A. forrestiana and the latter is similar to A. cucurbitoides and A. forrestiana. According to Ma’s (1989a) classification, both new species belong to Aristolochia subgenus Siphisia on the basis of the 3-lobed gynostemium and oblong anthers that are adnate in pairs, opposite the gynostemium lobes. Meanwhile, the two new species are assessed as Vulnerable (VU D2) according to IUCN Red List criteria.
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