The complete chloroplast genome of Semiaquilegia danxiashanensis (Ranunculaceae), a rare species endemic to Danxia landform in Guangdong, China.

Semiaquilegia danxiashanensis is currently known only from the type locality, Danxia Mountain, characterized by its spectacular red sandstone cliffscape. In this study, we assembled the complete chloroplast genome sequence of S. danxiashanensis and inferred its phylogenetic relationships. Total length of the chloroplast genome was 160,548 bp, with an overall GC content of 39%. The chloroplast genome had typical quadripartite structure and contained one LSC region (89,882 bp) and one SSC region (17,386 bp), which were separated by two IRs regions (26,640 bp, respectively). It comprised 133 genes, including 84 protein coding genes, 41 tRNA genes and eight rRNA genes. The maximum likelihood phylogenetic analysis indicated that S. danxiashanensis was sister to S. adoxoides; meanwhile, Semiaquilegia was closely related to both Urophysa and Aquilegia in Ranunculaceae. This study sheds light on the evolutionary history of Semiaquilegia and provides preliminary data for future comparative analysis of chloroplast genomes.

Aspleniumguodanum (Aspleniaceae), a distinct new fern species from northern Guangdong, China, based on morphological data and molecular phylogeny.

A new spleenwort species, Aspleniumguodanum, was found and described from Danxia landform region in Guangdong, China. The new species has close resemblance to A.subcrenatum Ching ex S.H.Wu in morphology, but can be distinguished by having plants small, stipes and rachises not covered with fibrous scales, relatively fewer pairs of pinnae, pinnae short, pinna margin weakly biserrate, pinna apex acute and lower pinnae obviously reduced. Phylogenetic analyses, based on six plastid markers (atpB, rbcL, rps4 & rps4-trnS and trnL & trnL-F) of the new species and its relatives, support a close relationship between A.guodanum and A.subcrenatum. Only one population with no more than 50 individuals were found and, therefore, it is recommended to be classified as Critically Endangered (CR) following IUCN Red List Criteria.

Comparison of ecosystem health in different geomorphic regions of Chishui River Basin, Southwest China.

Ecosystem health of the Chishui River Basin (CRB, a crucial ecological barrier in the upper reaches of the Yangtze River) is vital for the ecological security and sustainability of the Yangtze River Basin. We used RUSLE model, SWAT model, Fragstats and geographic detectors to construct a theoretical framework of ecosystem health assessment for CRB, and examined the spatiotemporal variations and driving factors of ecosystem health in CRB under ecological restoration from 2010 to 2020. The results showed that ecosystem service in the CRB decreased and then increased during 2010-2020 and the overall trend was downward. The overall ecosystem service function was higher in the Danxia (non-karst) area than that in the karst area. The ecosystem health was generally subhealthy, with the Danxia area being mostly extremely healthy and healthy, whereas the karst area mostly subhealthy and unhealthy. There were differences in the dominant drivers of ecosystem health between karst and Danxia areas. Vegetation, precipitation, and bedrock bareness rate were the dominant drivers in the karst area, while vegetation, land use, and precipitation were the dominant factors in Danxia area. After interaction detection, the explanatory power of impact factors increased, and the dominant interaction factor combinations in different geomorphological type regions had shown great differences. Among them, precipitation∩normalized difference vegetation index (NDVI), precipitation∩digital elevation model (DEM) and precipitation ∩ bedrock bareness rate were the dominant interaction factor combinations in the karst area, and NDVI∩precipitation, NDVI∩land use and NDVI∩DEM were the dominant interaction factor combinations in Danxia area. These results would provide scientific support for health maintenance and conservation of CRB ecosystem.

Selaginellawuyishanensis (sect. Tetragonostachyae, Selaginellaceae), a new species from East China and its phylogenetic position based on molecular data.

A new spikemoss species, Selaginellawuyishanensis, is described and illustrated based on materials collected from Fujian Province, East China. The new species can be distinguished from S.lutchuensis Koidzumi and S.albociliata P. S. Wang by its leaves with extremely long cilia (up to 8 mm) and distinctly white margins, ovate ventral sporophylls, and sporophyll-pteryx completely inverted on dorsal sporophylls. In the present work, a molecular phylogeny, taxonomic description, distribution information, line drawing, and photographs of this new species are presented. A morphological comparison is also given to distinguish it from morphologically similar species in Selaginellasect.Tetragonostachyae (Hook. & Grev.) Hieron. & Sadeb.

Wikstroemiafragrans (Thymelaeaceae, Daphneae), a new species from Mount Danxia, China based on morphological and molecular evidence.

A new species, Wikstroemiafragrans (Thymelaeaceae, Daphneae), from Danxiashan National Park, Shaoguan, Guangdong of China is described and illustrated. It is similar to the sympatric W.trichotoma, but can be differentiated easily from the latter by its shorter racemose inflorescences, yellowish green calyx tube, and smaller leaves. It also resembles the allopatric W.fargesii, but differs from it by its strigose-pubescent ovary and disk scale that is 2- or 3-dentate apically. Phylogenetic analysis using the nuclear DNA internal transcribed spacer (ITS) region revealed that W.fragrans falls within the Wikstroemia clade; based on current sampling, W.fragrans is closely-related to W.capitata. It is also the first species of Wikstroemia known to be endemic to the Danxia landform and is classified provisionally as Critically Endangered according to the IUCN Red List Categories and Criteria.

Lespedezadanxiaensis (Fabaceae), a new species from Guangdong, China, based on molecular and morphological data.

Lespedezadanxiaensis (Fabaceae), a new species from Danxiashan National Nature Reserve in Guangdong Province, is described and illustrated. The new species is morphologically similar to Lespedezapilosa, but it can be easily distinguished by its thin leathery leaflets and long peduncles. Phylogenetic analysis based on ITS confirmed that the new species belongs to Lespedezasubg.Macrolespedeza. The new species is the first known species of Lespedeza endemic to Danxia landform and is currently only known from Mount Danxia, Guangdong.

Strong Genetic Structure Observed in Primulina danxiaensis, a Small Herb Endemic to Mount Danxia With Extremely Small Populations.

Danxia landform occurring sporadically in southern China is a unique type of petrographic geomorphology. It has nurtured about 400 rare or threatened plant and animal species, whose diversity, endemism, and conservation have called increasing scientific and public attentions. Among them, Primulina danxiaensis (W. B. Liao, S. S. Lin, and R. J. Shen) W. B. Liao and K. F. Chung is a tiny perennial grass species recorded only in Mount Danxia, a natural World Heritage Site as part of China's Danxia. In this study, restriction site-associated DNA sequencing (RAD-seq) was performed to investigate genetic diversity among these 12 populations of P. danxiaensis. A total of 432,041 variant sites were detected in 84,779 loci across 94 samples. The expected heterozygosity (H E ) ranged from 0.017 to 0.139. Bottleneck signals were detected in most populations, Tajima's D tests showed that most loci could be under recent positive selection, and one of the six positively selected loci identified by BayeScan was annotated as tRNAGlu, which may contribute to the species' adaptation to shady environment. STRUCTURE analysis and phylogenetic tree showed that the 12 populations of P. danxiaensis could be divided into four gene pools (clades) corresponding to their geographic locations, and significant correlation was observed between genetic and geographic distances. Our study demonstrated that P. danxiaensis maintained a middle level of genetic diversity and strong population structure; geographic distance could be an important factor limiting gene flow among populations of P. danxiaensis, which were only sporadically recorded in Mount Danxia.

Impatiens wuyiensis (Balsaminaceae), a new species from Fujian of Southeast China, based on morphological and molecular evidences.

BACKGROUND: Southeast Asia, together with tropical Africa, Madagascar, South India and Sri Lanka, and the eastern Himalayas, are the five primary hotspots of species diversity of Impatiens (Balsaminaceae). China is also rich in Impatiens species, especially in the limestone karsts or 'Danxia' landforms. With zygomorphic flowers and diverse corolla morphology and color, the species in Impatiens are well-known for their ornamental use, but they are also notorious in taxonomy. During the preparation of revision of Impatiens in Zhejiang and adjacent regions, an unknown species was collected from Mt. Wuyi in Fujian Province, Southeast China. RESULTS: Phylogenetic analyses based on nuclear ITS, chloroplast atpB-rbcL and trnL-F sequences, together with micromorphology of pollen grains and seed coats, strongly supported the close relationship of the new species with Impatiens platysepala Y.L.Chen and I. chloroxantha Y.L.Chen. In turn, both molecular data and morphological characters also were sufficient to distinguish the new species from the other two counterparts. CONCLUSIONS: Our detailed morphological observations and molecular phylogenetic analyses support the recognition of Impatiens wuyiensis as a species new to science.