Among the four species of Echinacanthus (Acanthaceae), one distributed in the West Himalayan region and three restricted to the Sino-Vietnamese karst region. Because of its ecological significance, molecular markers are necessary for proper assessment of its genetic diversity and phylogenetic relationships. Herein, the complete chloroplast genomes of four Echinacanthus species were determined for the first time. The results indicated that all the chloroplast genomes were mapped as a circular structure and each genomes included 113 unique genes, of which 80 were protein-coding, 29 were tRNAs, and 4 were rRNAs. However, the four cp genomes ranged from 151,333 to 152,672 bp in length. Comparison of the four cp genomes showed that the divergence level was greater between geographic groups. We also analyzed IR expansion or contraction in the four cp genomes and the fifth type of the large single copy/inverted repeat region in Lamiales was suggested. Furthermore, based on the analyses of comparison and nucleotide variability, six most divergent sequences (rrn16, ycf1, ndhA, rps16-trnQ-UUG, trnS-GCU-trnG-UCC, and psaA-ycf3) were identified. A total of 37–45 simple sequence repeats were discovered in the four species and 22 SSRs were identified as candidate effective molecular markers for detecting interspecies polymorphisms. These SSRs and hotspot regions could be used as potential molecular markers for future study. Phylogenetic analysis based on Bayesian and parsimony methods did not support the monophyly of Echinacanthus. The phylogenetic relationships among the four species were clearly resolved and the results supported the recognition of the Sino-Vietnamese Echinacanthus species as a new genus. Based on the protein sequence evolution analysis, 12 genes (rpl14, rpl16, rps4, rps15, rps18, rps19, psbK, psbN, ndhC, ndhJ, rpoB, and infA) were detected under positive selection in branch of Sino-Vietnamese Echinacanthus species. These genes will lead to understanding the adaptation of Echinacanthus species to karst environment. The study will help to resolve the phylogenetic relationship and understand the adaptive evolution of Echinacanthus. It will also provide genomic resources and potential markers suitable for future species identification and speciation studies of the genus.

Justicia L. is the most species-rich genus of Acanthaceae in Peru and is here accepted in its broader traditional circumscription. The present paper marks a preliminary step towards a complete revision of the genus in Peru. Taxonomic notes and full synonymy are provided for 45 species including twenty-one new species, all apparently endemic to Peru: Justicia angustituba J.R.I.Wood & R.Villanueva, J. baguensis J.R.I.Wood & R.Villanueva, J. bambusiformis J.R.I.Wood & R.Villanueva, J. chamaecaulis J.R.I.Wood & R.Villanueva, J. cajamarcensis R. Villanueva & J.R.I.Wood, J. discolor J.R.I.Wood & R.Villanueva, J. falcifolia J.R.I.Wood & R.Villanueva, J. huallagensis R.Villanueva & J.R.I.Wood, J. hyalina J.R.I.Wood & R. Villanueva, J. lactiflora J.R.I.Wood & R.Villanueva, J. longibracteata J.R.I.Wood & R.Villanueva, J. oppositiflora R.Villanueva & J.R.I.Wood, J. oxapampensis R. Villanueva & J.R.I.Wood, J. rojasiae R.Villanueva & J,R.I.Wood, J. saccata R.Villanueva & J.R.I.Wood, J. sagasteguii J.R.I.Wood & R.Villanueva, J. schunkei J.R.I.Wood & R. Villanueva, J. spathuliformis R.Villanueva & J.R.I.Wood, J. tumbesiana R.Villanueva & J.R.I.Wood, J. valenzuelae J.R.I.Wood & R.Villanueva and J. werffii J.R.I.Wood & R.Villanueva. New subspecies, subsp. machupicchuensis J.R.I.Wood & R.Villanueva of J. alpina Lindau and subsp. filisepala J.R.I.Wood & R.Villanueva of J. discolor are described. The genus Tessmanniacanthus Mildbr. is united with Justicia, the only species in the genus, T. chlamydocardioides Mildbr. being treated as Justicia chlamydocardioides (Mildbr.) R.Villanueva & J.R.I.Wood. Justicia loxensis Wassh., J. poeppigiana (Nees) Lindau, J. sessilifolia (Lindau) Wassh., J. soukupii (Standl. & F.A. Barkley) V.A.W.Graham and J. tenuistachys (Rusby) Wassh. & J.R.I.Wood are treated as synonyms respectively of J. chimboracensis Wassh., J. secundiflora (Ruiz & Pav.) Vahl, J. alpina Lindau, J. radicans Vahl and J. tenuiflora Ruiz & Pav. Fourteen names are lectotypified. The paper is copiously illustrated with line drawings, photographs and pollen images. Distribution maps supplement the information on ecology and distribution provided for all species discussed.

The genusDicliptera(Justicieae, Acanthaceae) consists of approximately 150 species distributed throughout the tropical and subtropical regions of the world. Newly obtained chloroplast genomes (cp genomes) are reported for five species ofDilciptera(D. acuminata,D. peruviana,D. montana,D. ruizianaandD. mucronata) in this study. These cp genomes have circular structures of 150,689–150,811 bp and exhibit quadripartite organizations made up of a large single copy region (LSC, 82,796–82,919 bp), a small single copy region (SSC, 17,084–17,092 bp), and a pair of inverted repeat regions (IRs, 25,401–25,408 bp). Guanine-Cytosine (GC) content makes up 37.9%–38.0% of the total content. The complete cp genomes contain 114 unique genes, including 80 protein-coding genes, 30 transfer RNA (tRNA) genes, and four ribosomal RNA (rRNA) genes. Comparative analyses of nucleotide variability (Pi) reveal the five most variable regions (trnY-GUA-trnE-UUC, trnG-GCC, psbZ-trnG-GCC, petN-psbM,andrps4-trnL-UUA), which may be used as molecular markers in future taxonomic identification and phylogenetic analyses ofDicliptera. A total of 55-58 simple sequence repeats (SSRs) and 229 long repeats were identified in the cp genomes of the fiveDiclipteraspecies. Phylogenetic analysis identified a close relationship betweenD. ruizianaandD. montana, followed byD. acuminata,D. peruviana, andD. mucronata. Evolutionary analysis of orthologous protein-coding genes within the family Acanthaceae revealed only one gene,ycf15,to be under positive selection, which may contribute to future studies of its adaptive evolution. The completed genomes are useful for future research on species identification, phylogenetic relationships, and the adaptive evolution of theDiclipteraspecies.

Acanthus is a unique genus consisting of both true mangrove and terrestrial species; thus, it represents an ideal system for studying the origin and adaptive evolution of mangrove plants to intertidal environments. However, little is known regarding the two respects of mangrove species in Acanthus. In this study, we sequenced the transcriptomes of the pooled roots and leaves tissues for a mangrove species, Acanthus ilicifolius, and its terrestrial congener, A. leucostachyus, to illustrate the origin of the mangrove species in this genus and their adaptive evolution to harsh habitats. We obtained 73,039 and 69,580 contigs with N50 values of 741 and 1557 bp for A. ilicifolius and A. leucostachyus, respectively. Phylogenetic analyses based on four nuclear segments and three chloroplast fragments revealed that mangroves and terrestrial species in Acanthus fell into different clades, indicating a single origin of the mangrove species in Acanthus. Based on 6634 orthologs, A. ilicifolius and A. leucostachyus were found to be highly divergent, with a peak of synonymous substitution rate (Ks) distribution of 0.145 and an estimated divergence time of approximately 16.8 million years ago (MYA). The transgression in the Early to Middle Miocene may be the major reason for the entry of the mangrove lineage of Acanthus into intertidal environments. Gene ontology (GO) classifications of the full transcriptomes did not show any apparent differences between A. ilicifolius and A. leucostachyus, suggesting the absence of gene components specific to the mangrove transcriptomes. A total of 99 genes in A. ilicifolius were identified with signals of positive selection. Twenty-three of the 99 positively selected genes (PSGs) were found to be involved in salt, heat and ultraviolet stress tolerance, seed germination and embryo development under periodic inundation. These stress-tolerance related PSGs may be crucial for the adaptation of the mangrove species in this genus to stressful marine environments and may contribute to speciation in Acanthus. We characterized the transcriptomes of one mangrove species of Acanthus, A. ilicifolius, and its terrestrial relative, A. leucostachyus, and provided insights into the origin of the mangrove Acanthus species and their adaptive evolution to abiotic stresses in intertidal environments.

Aphelandra knappiae is an important plant from the family Acanthaceae. The complete chloroplast genome of the genus Aphelandra was sequenced for the first time. The plastome of A. knappiae was 152,457 bp in length. It consisted of a large single-copy (LSC) region (83861 bp) and a small single-copy (SSC) region (17,888 bp), which were separated by two inverted repeats (IRs, 25,354 bp). This plastome contained 114 unique genes, including 80 protein-coding genes, 30 tRNAgenes, and 4 rRNA genes. The overall GC content was 38.5%. Furthermore, phylogenetic analysis of five species in the Acanthaceae was also conducted. The whole chloroplast genome of this species will be useful for the future plant evolutionary, phylogeny and genomic studies in the family Acanthaceae.

A new species, Lysimachia huangsangensis (Primulaceae), from Hunan, China is described and illustrated. The new species is closely related to L. carinata because of the crested calyx, but differs in the leaf blades that are ovate to elliptic and (3–)4.5–9 × 2–3.4 cm, 2–5-flowered racemes, and the calyx lobes that are ovate-lanceolate and 5–6 × 3–4 mm. The systematic placement and conservation status are also discussed.