Updated distribution and new emerging populations of Cynometracebuensis F. Seid. (Fabaceae), a critically endangered endemic plant from the Philippines.

Background: Cynometracebuensis F. Seid. is an endemic and threatened tree from the Philippines. The species was previously described to exclusively thrive in the Tabunan Forest of the Central Cebu Protected Landscape. Due to its narrow geographic distribution and threats from land conversion, slash-and-burn activities and non-regulated wood harvesting by locals, C.cebuensis was assessed as Critically Endangered (CR) under criteria B1a and B1b (as well as B2a and B2b) of the IUCN Red List in 2013. The present study provides new additional locations of C.cebuensis in the Municipalities of Argao and Minglanilla in Cebu along with population data and habitat characteristics for each site. Although new populations of C.cebuensis were discovered, it remains at significant risk of extinction in its natural habitat. Urgent and comprehensive conservation efforts are imperative to prevent its extinction. New information: This paper provides the updated distribution map of Cynometracebuensis F. Seid, a critically endangered endemic species in the Philippines showing five (5) distribution records.

Evaluating building stones: Physical-mechanical changes from high-temperature fire and water cooling.

Heritage sites built with natural stone are at risk from fires, which can alter stone properties and compromise its structural integrity. Over 60 studies in the past three decades have examined fire impact on natural stone, providing insights for their prevention and restoration. The primary objectives are to develop effective strategies to mitigate fire risks, protect heritage structures, and ensure the preservation of our cultural legacy. Two noteworthy Portuguese limestones used as heritage building materials: Lioz (LL) and grey Ançã stone (GAS), were studied regarding the effect of high-temperature exposure for simulating fire at 200 °C, 400 °C and 600 °C, followed by cooling in water to reproduce fire extinguish in natural stone buildings. The findings provided insights into how the different temperatures impact the stone morphological, physical and mechanical properties. Color measurements (CIE L*a*b*) showed a color difference from 3 to 32 %; SEM-EDS confirmed microstructure modifications after fire exposure with cracks formation and intragranular porosity development. Among the diverse physical and mechanical properties of the stones, uniaxial compressive strength decreased from 1 to 33 %, Leeb D hardness decreased up to 12.2 %, lowering in open porosity was detected in the range 70-289 % and ultrasound speed propagation were significantly affected after thermal cycle at 600 °C with a negative variation reaching 49 %. Results from TGA show a loss of mass due to retained water (∼40 °C) and loss of hydration water at âˆ¼ 120 °C in both limestones. The total mass loss (∼42-∼44 %) is associated with the loss of H2O, CO2. In conclusion, stones with higher toughness and compression strength exhibited reduced damage at high temperatures due to their enhanced resistance to fracturing under stress. As limestone's mechanical strength decreases under high temperatures, it's advisable to increase its thickness to ensure sufficient support for loads and intended conditions of use. The deficiency of analysis on limestone's mechanical decay from fire reveals a significant knowledge gap regarding the complete extent of damage and deterioration in stone heritage structures.

Integrative taxonomy reveals two new giant pill-millipedes of the genus Zephronia Gray, 1832 from eastern Thailand (Diplopoda, Sphaerotheriida, Zephroniidae).

A large amount of material of the millipede genus Zephronia Gray, 1832 was collected during 2014-2023 from many parts of eastern Thailand. An integrative study of morphological characters and genetic data (COI gene) revealed two new species: Z.chantaburiensis Srisonchai & Wesener, sp. nov. and Z.macula Srisonchai & Wesener, sp. nov. The two new species clearly differ from other congeners by their unique characteristics, especially in their colour pattern and telopod shape. The interspecific genetic distances of the 658 bp COI gene barcoding fragment between these new species and all other species of giant pill-millipede from Thailand, Laos and Cambodia are 12.01-23.49% for Z.chantaburiensis sp. nov. and 17.93-25.13% for Z.macula sp. nov. While relationships among species remain preliminary, the phylogenetic tree shows that species of Zephronia are interspersed with species of Sphaerobelum Verhoeff, 1924 and Prionobelum Verhoeff, 1924. Phylogenetic analyses place both new species in a clade termed Zephronia s.s., which receives support also from morphological data, showing a unique position of the organ of Tömösváry. Z.macula sp. nov. appears to occur over a broad distribution whereas Z.chantaburiensis sp. nov. was found only at the type locality. Given that all known records are in the eastern part of Thailand, we thus regard both species as endemic. Morphological illustrations based on SEM micrographs and a distribution map are also provided.

Effects of Dolomitic Limestone on the Properties of Magnesium Oxysulfate Cement.

This study investigated the effects of substituting magnesium oxide (MgO) with dolomitic limestone (DL) on the mechanical and physical properties of magnesium oxysulfate (MOS) cement. Additionally, the hydration formation phases and the influence of the molar ratio on the MOS cement's performance were examined. The corresponding action mechanisms were identified and explored by compressive strength tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), isothermal calorimetry, and a thermogravimetric analysis (TGA). The results showed that replacing MgO with DL decreased the reaction speed and heat release rate generated in the hydration process of the MOS cement. This substitution also reduced the quantity of non-hydrated MgO particles and delayed the formation of Mg(OH)2. The diminished formation of Mg(OH)2 contributed to an increase in the apparent porosity of pastes containing DL, thus alleviating internal stresses induced by Mg(OH)2 formation and enhancing their mechanical strength after 28 days of curing. Conversely, the increased porosity improved the CO2 diffusion within the structure, promoting the formation of magnesium carbonates (MgCO3). Through the characterization of the cement matrix (XRD and TGA), it was possible to identify phases, such as the brucite, periclase, and 318 phases. The obtained results revealed the potential of incorporating mineral fillers like limestone as a promising approach to producing MOS cement with a reduced environmental impact and better properties at higher curing ages.

The Synergistic Effect of Calcained Coal-Series Kaolinite and Limestone on the Hydration of Portland Cement.

Limestone calcined clay cement (LC3) presents a promising alternative material due to its reduced CO2 emissions and superior mechanical properties compared to traditional Portland cement (PC). This study investigates the synergistic effect of calcined coal-series kaolinite (CCK) and limestone (LS) on the hydration behavior of cement, specifically focusing on varying mass ratios. The combination of CCK and LS promotes the formation of strätlingite and carboaluminates, which enhances early-age strength development. Additionally, the inclusion of CCK facilitates the formation of carboaluminates during later stages of hydration. After 56 days of hydration, the content of carboaluminates is over 10%wt. This stimulation of secondary hydration products significantly refines the evolution of pore structure, with the harmful large pores gradually transformed into harmless medium pores and gel pores, leading to marked improvements in compressive strength from 7 to 28 days. Replacing 45% PC with CCK and LS at mass ratio of 7 to 2, the compressive strength of blends reaches 47.2 MPa at 28 days. Overall, the synergistic interaction between CCK and LS presents unique opportunities to minimize the CO2 footprint of the cement industry without compromising early and long-term performance.

Calcium and phosphorus digestibility in broilers as affected by varying phytate concentrations from corn.

Dietary phytate P (PP) concentration impacts Ca and P digestibility in broilers. Research was conducted to determine the impact of increasing concentration of dietary PP, with and without phytase, on broiler standardized ileal digestibility (SID) of Ca and P. Digestible (Dig) Ca and P were calculated by multiplying SID and the analyzed dietary Ca and P concentrations. The experiment was a factorial arrangement of 2 phytase (0 and 1,000 U/kg) and 4 PP (0.16, 0.23, 0.29, and 0.34%) concentrations. Treatments were fed for 36 h from 20 to 22 d of age (4 b/pen, n ≥ 7 replicate pens/treatment). Different ratios of corn and corn germ were used to achieve the desired PP concentrations. A limestone with 800 µm geometric mean diameter was used as the sole Ca source to achieve 0.7% Ca in the final diets (96% Ca from limestone). An additional diet was fed that was N, Ca- and P-free, for the determination of endogenous losses of each nutrient. Distal ileal digesta were pooled from all birds in a pen. There were no interactions between PP and phytase on SID Ca or Dig Ca from limestone. Irrespective of phytase inclusion, increasing PP from 0.16 to 0.34% decreased SID Ca from 53.8 to 38.1% (P < 0.05). The SID Ca averaged 41.5 and 51.4% in diets containing 0 and 1000 U phytase/kg, respectively, across all PP concentrations (P < 0.05). Interactions were seen between PP and phytase on SID and Dig P (P < 0.05) with SID P of 31.1, 24.0, 20.1, and 16.3% for broilers fed 0.16, 0.23, 0.29, and 0.34% PP diets without phytase, respectively. When phytase was included at 1000 U/kg, SID P was 89.9, 87.5, 73.9 and 60.4% for diets containing 0.16, 0.23, 0.29 and 0.34% PP, respectively (P < 0.05). Overall, phytase improved SID Ca and P independent of PP concentration. However, with increasing PP concentration, both SID Ca and P were negatively affected.

Determination of calcium digestibility and bioavailability in 5 limestone sources using commercial broiler and crossbred chickens.

Three experiments were conducted to determine effect of feeding 5 commercial limestones varying in solubility (88-97%), mean particle size (500-700 microns), and geographical origin on Ca bioavailability and digestibility in commercial broiler and crossbred chickens. In Experiment 1, both crossbred and commercial chickens were used to measure the effect of dietary Ca level on tibia bone ash to develop a slope-ratio Ca bioavailability assay. Chickens were fed diets that contained Ca levels ranging from 0.20% to 0.95% from 9 to 22 d-of-age. Regressions of bone ash (mg/tibia and %) on supplemental Ca intake yielded large linear responses in both types of chickens in Experiment 1. In Experiment 2, relative bioavailability of Ca in 5 limestones using bone ash as primary response criterion was determined. Thirteen diets were fed to commercial Ross 308 male broilers which were either a Ca-deficient diet (0.30% Ca) or that diet supplemented 0.15 or 0.30% Ca from either reagent grade calcium carbonate (RCaCO3) or 1 of the 5 commercial limestones from 9 to 22 d-of-age. Bioavailability of Ca in limestones relative to RCaCO3 was determined using multiple linear regression of bone ash (mg/tibia and %) on supplemental Ca intake, which yielded slope-ratio relative Ca bioavailability values ranging from 90% to 106% in Experiment 2. In Experiment 3, apparent ileal digestibility (AID) and apparent total tract retention (TTR) of Ca in broiler chickens was measured for the 5 limestones using corn-based diets. The AID and TTR of Ca at 21 d-of-age were low and variable with a range of 20 to 34% for AID of Ca and 12 to 31% for TTR of Ca. Results from these studies indicate that a slope-ratio bone ash assay with either crossbred or modern commercial chickens can be used to measure relative bioavailability of Ca in limestones and there were few consistent differences in relative Ca bioavailability, AID of Ca, and TTR of Ca among 5 commercial limestones evaluated herein.

Superhydrophobicity, Photocatalytic Self-Cleaning and Biocidal Activity Combined in a Siloxane-ZnO Composite for the Protection of Limestone.

The erosion phenomena of the natural stone in cultural heritage are induced by various sources. Consequently, the development of multifunctional protective materials that combine two or more useful properties is an effective strategy in addressing the synergistic effects of various erosion mechanisms. A multifunctional coating, consisting of a silane-based precursor and zinc oxide (ZnO) nanoparticles (NPs), is produced and tested for the protection of limestone. The hybrid coating combines the following three properties: superhydrophobicity, including water-repellency, photocatalytic self-cleaning and biocidal activity. The relative concentration of the NPs (0.8% w/w), used for the suggested composite coating, is carefully selected according to wetting studies, colourimetric measurements and durability (tape peeling) tests. The non-wetting state is evidenced on the surface of the composite coating by the large contact angle of water drops (≈153°) and the small contact angle hysteresis (≈5°), which gives rise to a physical self-cleaning scenario (lotus effect). The photocatalytic chemical self-cleaning is shown with the removal of methylene blue, induced by UV-A radiation. Moreover, it is shown that the suggested coating hinders the incubation of E. coli and S. aureus, as the inhibitions are 94.8 and 99.9%, respectively. Finally, preliminary studies reveal the chemical stability of the suggested coating.

Current advances and future prospects of in-situ desulfurization processes in oxy-fuel combustion reactors.

Oxy-fuel circulating fluidized bed combustion is known as one of the most potent fuel combustion technologies that capture ultra-low greenhouse gases and pollutant emissions. While many investigations have been conducted for carbon capturing, the associated in-situ desulfurization process using calcium-based sorbents should also be underlined. This paper critically reviews the effects of changes in the operating environment on in-situ desulfurization processes compared to conventional air combustion. A comprehensive understanding of the process, encompassing hydrodynamic, physical and chemical aspects can be a guideline for designing the oxy-fuel combustion process with effective sulfur removal, potentially eliminating the need of a flue gas desulfurization unit. Results from thermogravimetric analyzers and morphological changes of calcium-based materials were presented to offer an insight into the sulfation mechanisms involved in the oxy-fuel circulating fluidized beds. Recently findings suggested that in-situ direct desulfurization is influenced not only by the desulfurization kinetics but also by the fluidization characteristics of calcium-based materials. Therefore, a complex reaction analysis that incorporated oxy-combustion reactions, computational fluid dynamics modeling, in-situ desulfurization reaction models and particle behavior can provide a thorough understanding of desulfurization processes across the reactor. Meanwhile, machine learning as a robust tool to predict desulfurization efficiency and improve operational flexibility should be applied with consideration of environmental improvement and economic feasibility.

Salt Crystallization in Limestone: Materials Decay and Chemomechanical Approach.

Salt crystallization is a particularly relevant issue in the conservation of limestones used in Cultural Heritage sites. In this study, various facies of limestones were characterized through porosimetric and mechanical tests. The samples were subjected to experiments to determine their resistance to salt crystallization by verifying the number of cycles at which 50% of them began to lose weight. This number of experimental cycles was compared with the result calculated by the analytical procedure of a chemomechanical model found in the literature. The comparison showed a significant capability of the model to predict the experimental data.

Cadmium Minimization in Grains of Maize and Wheat Grown on Smelting-Impacted Land Ameliorated by Limestone.

Cadmium (Cd) contamination in agricultural soils has emerged as a significant concern, particularly due to its potential impact on plant-based food. Soil pH reductions can exacerbate Cd mobility, leading to excessive accumulation in crops. While liming has been demonstrated as an effective method to mitigate Cd accumulation in rice grains in acid soils of southern China, its efficacy in remediating acid soils in northern China remains unclear. In this study, a multi-year field experiment was conducted on farmland impacted by zinc ore smelting at coordinates of 33.92° N 112.46° E to investigate the use of limestone for controlling Cd accumulation in wheat and maize grains. The results indicated that applying 7.5 t ha-1 of limestone significantly raised the soil pH from 4.5 to 6.8 as anticipated. Different rates of limestone application (2.25, 4.45, and 7.50 t ha-1) reduced Cd bioavailability in the soil by 20-54%, and Cd accumulation in wheat grains by 5-38% and maize grains by 21-63%, without yield penalty. The remediation effects were sustained for at least 27 months, highlighting limestone as a promising ameliorant for smelting-affected farmland in northern China.

Arsenic and metal levels in snake tissues from Lagoa Santa Karst, Brazil.

Concentrations of one metalloid (As) and eight metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were determined in tissues (muscle, liver, and kidney) of eight snake species (Bothrops neuwiedi, Crotalus durissus, Dipsas mikanii, Epicrates crassus, Helicops modestus, Micrurus carvalhoi, Oxyrhopus guibei, and Oxyrhopus trigeminus) from Lagoa Santa Karst. Except for Cu and Zn, all other analyzed elements were detected in concentrations within the ranges previously reported for snakes inhabiting polluted areas, emphasizing Hg (specific Hg mean concentrations varied from 0.87 to 9.76 µg g-1 d.w). The highest mean concentrations of all elements except Zn were found in muscle samples of the false corals O. guibei (means ranged from 2.01 [Pb] to 9.76 [Hg]). The highest Zn mean concentration (13.77 µg g-1 d.w) was detected in the kidney of the water snake H. modestus. No significant correlation was found between element concentrations and body size for all species. Significant interorgan differences were observed for As, Cr, Cu, Hg, Mn, Pb, and Zn concentrations in the three tissues in H. modestus. Significant interspecific differences were found in at least one organ for all elements. Significant pairwise differences were found between diet specialist species and between these species and broader diet species, while no significant difference was found between the broader diet species. The bioaccumulation of As and metals in snakes from Lagoa Santa Karst could be associated with natural rock dissolution and erosion processes but also with the wide-scale mining in the region and the increased agriculture and urbanization.

Yushaniadezhui (Poaceae, Bambusoideae), a new bamboo species from Yunnan, China.

A new bamboo species, Yushaniadezhui, from Kunming, Yunnan, China is described and illustrated in this paper. The new species used to be misidentified as Y.polytricha. Based on careful comparison of morphological features and molecular phylogeny evidence, we confirmed its identity as a new member of the genus Yushania. Yushaniadezhui resembles Y.maculata, Y.polytricha and Y.weixiensis in several aspects, such as culm height and branch complement structure. However, the glabrous culm leaf sheaths and internodes, the absence of auricles and oral setae on most foliage leaves, except the one-year-old foliage leaves, the pubescence on the adaxial surface of the one-year-old foliage leaves and its limestone habitat preference can readily distinguish this new species from its related taxa. Moreover, we emphasise that individuals from various populations and molecular markers with different inheritance patterns for phylogeny reconstruction should be included in new species discovery, especially in plant groups with complex evolutionary histories.

Tension Capacity of Crushed Limestone-Cement Grout.

The feasibility of using crushed limestone instead of sand in cement grout is examined in this work. This study entails performing several tests, including the Brazilian test, the compressive strength test, and the stress-strain correlation test. The curing times used were 7, 14, and 28 days for mixtures with various proportions of cement to limestone (1:1, 1:2, and 1:4). The conventional sand-cement grout laboratory tests were prepared using a similar methodology to examine the effectiveness of the suggested substitute. The findings show that the limestone-based grout has sufficient strength, but that it is less than that of the typical sand material. The values of the tensile strength and elastic modulus were determined. A focus was made on the tensile strength and stress-strain relationship. A special laboratory set-up was used to look at the progress of failure using strain gauges fitted to the cylindrical samples both vertically and horizontally. The angular shape of the particles' ability to interlock is responsible for the material's increase in strength. According to this study, crushed limestone can be used as a substitute for sand in circumstances where sand supply is constrained. The suggested grout can be used in the shotcrete of tunnels and rock surfaces.

Harnessing phosphate limestone waste as a cost-effective solution for acid mine drainage treatment.

Mining mineral ores like pyrrhotite often generates positive and negative outcomes for the community. On the one hand these valuable minerals are explored to provide economic opportunities. On the other, mining pyrrhotite presents adverse environmental and health effects that relates to acid mine drainage (AMD) formation in abandoned mines. This suggest that the sustainable mining of valuable minerals in Pyrrhotite requires cost and environmentally friendly approaches. In this research, we simulate in-situ neutralisation effect of phosphate limestone waste (PLW) on AMD from two mining sites in Morocco under continuous oxic conditions. To this end, we conducted batch tests to assess the effectiveness of PLW in mitigating AMD and releasing contaminants. These tests involved reacting limestone particles (at two sizes: <2 cm and < 4 cm) with AMD leachates over a five-day period The results indicated that the AMD is characterised by a pH of 2.5 and an electrical conductivity of 11.8 mS/cm. The inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses showed a high sulfate concentration of 3668.83 mg/L and the presence of some metals, notably copper, aluminium, and iron. The neutralisation process of the AMD using PLW under oxic conditions was highlighted by the variation in pH while the water was in contact with the PLW. The pH rose from 2.5 to 5.25 while the electrical conductivity decreased from 11.8 to 7.03 mS/cm. During the treatment of the AMD with PLW, the percentage of sulfate removal from the effluent was 35 %. In addition, iron and aluminium were significantly removed from the AMD with a percentage of 99 % in the leachate. Therefore, these results indicate that neutralising AMD using this passive treatment approach is effective and may serve as a cost-effective mitigation for AMD, since no excessive grinding is required for the PLW.

Preparation of an environment-friendly microbial limestone dust suppressant and its dust suppression mechanism.

The development of an efficient and environmentally friendly dust suppressant is crucial to address the issue of dust pollution in limestone mines. Leveraging the synergistic microbial-induced calcium carbonate precipitation (MICP) technology involving NaHCO3 and dodecyl glucoside (APG), the optimal ratio of the dust suppressant was determined through single-factor and response surface tests. The dust suppression efficacy and mechanisms were analyzed through performance testing and microscopic imaging techniques, indicating that the optimal ratio of the new microbial dust suppressant was 20% mineralized bacteria cultured for 72 h, 0.647 mol L-1 cementing solution, 3.142% NaHCO3, and 0.149% APG. Under these conditions, the yield of calcium carbonate increased by 24.89% as compared to when no NaHCO3 was added. The dust suppressant demonstrated excellent wind, moisture, and rain resistance, as well as curing ability. More calcite was formed in the dust samples after treatment, and the stable form of the dust suppressant contributed to consolidating the limestone dust into a cohesive mass. These findings indicate that the synergistic effect of NaHCO3 and APG significantly enhanced the dust suppression capabilities of the designed microbial dust suppressant.

Effects of Fineness and Morphology of Quartz in Siliceous Limestone on the Calcination Process and Quality of Cement Clinker.

With the increasing depletion of high-quality raw materials, siliceous limestone, sandstone and other hard-to-burn raw materials containing crystalline SiO2 are gradually being used to produce clinker. This study investigates the influence of the quartz content and particle size in siliceous limestone on the calcination process and the resultant quality of cement clinker. Two different siliceous limestones were grinded to different fineness, and calcinated with some other materials. The content of the clinkers was analyzed with the XRD-Rietveld method and the microstructure of the clinkers was observed with laser scanning confocal microscopy (LSCM) and field emission scanning electron microscopy (FESEM). Three key outcomes of this study provide new insights on the use of siliceous limestone in cement production, namely that (i) reducing the fineness values of siliceous limestone from 15% to 0% of residue on a 0.08 mm sieve decreases the quantity of these larger quartz particles, resulting in an increase in C3S content by up to 8% and an increase in 28d compressive strength by up to 4.4 Mpa, which is 62.30 Mpa; (ii) the morphology of quartz-either as chert nodules or single crystals-affects the microstructure of C2S clusters in clinker, finding that chert nodules result in clusters with more intermediate phases, whereas large single crystals lead to denser clusters; (iii) the sufficient fineness values of siliceous limestone SL1 and SL2 are 5% and 7% of residue on a 0.08 mm sieve, respectively, which can produce a clinker with a 28d compressive strength greater than 60 Mpa, indicating that for different kinds of quartz in siliceous limestone, there is an optimum grinding solution that can achieve a balance between clinker quality and energy consumption without having to grind siliceous limestone to very fine grades.

Impact of Different Mineral Reinforcements on HDPE Composites: Effects of Melt Flow Index and Particle Size on Physical and Mechanical Properties.

The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

Polygalaqii, a new species of Polygalaceae from limestone landform in Southern Hunan, China.

Polygalaqii, a new species, is described and illustrated from limestone landform in southern Hunan, China. The new species resembles P.fallax and P.arillata in flower structure of the plants, but readily differs from the latter two in having erect and shorter inflorescences (0.2-1cm VS 10-15cm VS 7-10cm), and fewer flowers (1-5 flowers VS 10-30 flowers VS 10-20 flowers), and the latter two have a later flowering period (late March to mid-April VS May to August VS May to October). And it is an extremely unique new species that will hibernate in the hot summer of July and August. Following the IUCN Red List Criteria, P.qii is assessed as 'Data Deficient (DD)'.

Cyrtomiumadenotrichum (Dryopteridaceae), a new species from Guangxi, China.

Cyrtomiumadenotrichum Y. Nong & R.H. Jiang (Dryopteridaceae), a new species from Guangxi, China, is described and illustrated. This new species is similar to C.nephrolepioides (Christ) Copel., C.obliquum Ching & K. H. Shing ex K. H. Shing, C.sinningense Ching & K. H. Shing ex K. H. Shing and C.calcis Liang Zhang, N.T.Lu & Li Bing Zhang in having erect rhizomes, dense, leathery lamina and rounded sori, but it can be easily distinguishable by its stipe sparsely glandular, base obvious oblique, basiscopic base truncate, acroscopic base auriculate or ovate.