Effects of plant hybridization on the structure and composition of a highly rich community of cynipid gall wasps: the case of the oak hybrid complex <Emphasis Type="Italic">Quercus magnoliifolia</Emphasis> x <Emphasis Type="Italic">Quercus resinosa</Emphasis> in Mexico

The richness and composition of herbivore communities can be influenced by the genetic variation of host plants. Hybrid plant populations are ideal to test these effects because they usually harbor high genetic variation and display a mosaic of phenotypic characters. The goal of this study was to examine the effect of hybridization between two Mexican white oaks, Q. magnoliifolia and Q. resinosa, on the composition and diversity of the associated cynipid gall wasp community. We used eight nuclear microsatellite markers to genotype 150 oak individuals sampled at three different altitudes at the Tequila volcano and conducted monthly samplings of galls in each individual over the course of 2 years. A Bayesian assignment analysis indicated genetic admixture between the two oak species at the study site and allowed classifying individuals as Q. magnoliifolia, Q. resinosa or hybrids. Gall morphospecies richness was significantly higher in the hybrids, intermediate in Q. magnoliifolia and lower in Q. resinosa. Overall, 48 different gall morphospecies were found, with 21 of them being shared among the three groups of plants, 13 between two groups of plants, and 14 were unique to one group of plants, with eight of these being found in hybrids. Several of the shared galls showed differences in abundance among plant groups. Therefore, genetic structure in this oak complex significantly influences the diversity and composition of the associated gall wasp community, and hybrid individuals are probably acting as potential sinks and bridges for the colonization of plant hosts by these highly specialized insect species.     

Geographic patterns of genetic variation in nuclear and chloroplast genomes of two related oaks (<Emphasis Type="Italic">Quercus aliena</Emphasis> and <Emphasis Type="Italic">Q. serrata</Emphasis>) in Japan: implications for seed and seedling transfer

In this study, we assessed geographic patterns of genetic variations in nuclear and chloroplast genomes of two related native oaks in Japan, Quercus aliena and Q. serrata, in order to facilitate development of genetic guidelines for transfer of planting stocks for each species. A total of 12 populations of Q. aliena and 44 populations of Q. serrata were analyzed in this study. Genotyping of nuclear microsatellites in Q. aliena was done with only nine populations (n = 212) due to limited numbers of individuals in two populations, while all 12 populations (n = 89) were used in sequencing chloroplast DNA (cpDNA). In Q. serrata, 43 populations (n = 1032) were genotyped by nuclear microsatellite markers, while cpDNA of 44 populations (n = 350) was sequenced. As anticipated, geographic patterns detected in the variations of Q. aliena’s nuclear genome and its chloroplast haplotype distribution clearly distinguished northern and southern groups of populations. However, those of Q. serrata were inconsistent. The geographic distribution of its chloroplast haplotypes tends to show the predicted differentiation between northern and southern lineages, but geographic signals in the genetic structure of its nuclear microsatellites are weak. Therefore, treating northern and southern regions of Japan as genetically distinct transferrable zones for planting stocks is highly warranted for Q. aliena. For Q. serrata, the strong NE-SW geographic structure of cpDNA should be considered.     

Investigating the genetic diversity and differentiation patterns in the <Emphasis Type="Italic">Penstemon scariosus</Emphasis> species complex under different sample sizes using AFLPs and SSRs

Habitat fragmentation due to anthropogenic activities is the major cause of biodiversity loss. Endemic and narrowly distributed species are the most susceptible to habitat degradation. Penstemon scariosus is one of many species whose natural habitat is vulnerable to industrialization. All varieties of P. scariosus (P. scariosus var. albifluvis, P. scariosus var. cyanomontanus, P. scariosus var. garrettii, P. scariosus var. scariosus) have small distribution ranges, but only P. scariosus var. albifluvis is being considered for listing under the Endangered Species Act. We used eight microsatellites or simple sequence repeats (SSRs) loci and two amplified fragment length polymorphism (AFLP) primer combinations to investigate the population genetic structure and diversity of P. scariosus varieties. Moreover, we compared the utility of the two marker systems in conservation genetics and estimated an appropriate sample size in population genetic studies. Genetic differentiation among populations based on F_st ranged from low to moderate (F_st?=?0.056–0.157) and from moderate to high when estimated with D_es (D_es?=?0.15–0.32). Also, AMOVA analysis shows that most of the genetic variation is within populations. Inbreeding coefficients (F_is) were high in all varieties (0.20–0.56). The Bayesian analysis, STRUCTURE, identified three clusters from SSR data and four clusters from AFLPs. Clusters were not consistent between marker systems and did not represent the current taxonomy. MEMGENE revealed that a high proportion of the genetic variation is due to geographic distance (R²?=?0.38, P?=?0.001). Comparing the genetic measurements from AFLPs and SSRs, we found that AFLP results were more accurate than SSR results across sample size when populations were larger than 25 individuals. As sample size decreases, the estimates become less stable in both AFLP and SSR datasets. Finally, this study provides insight into the population genetic structure of these varieties, which could be used in conservation efforts.     

Inheritance and gene mapping of the white flower trait in <Emphasis Type="Italic">Brassica juncea</Emphasis>

Despite being a unique marker trait, white flower inheritance in Brassica juncea remains poorly understood at the gene level. In this study, we investigated a B. juncea landrace with white petal in China. The white petal phenotype possessed defective chromoplasts with less plastoglobuli than the yellow petal phenotype. Genetic analysis confirmed that two independent recessive genes (Bjpc1 and Bjpc2) controlled the white flower trait. We then mapped the BjPC1 gene in a BC₄ population comprising 2295 individuals. We identified seven AFLP (amplified fragment length polymorphism) markers closely linked to the white flower gene. BLAST search revealed the sequence of AFLP fragments were highly homologous with the Scaffold000085 and Scaffold000031 sequences on the A02 chromosome in the Brassica rapa genome. Based on this sequence homology, we developed simple sequence repeat (SSR) primer pairs and identified 13 SSRs linked to the BjPC1 gene, including two that were co-segregated (SSR9 and SSR10). The two closest markers (SSR4 and SSR11) were respectively 0.9 and 0.4 cM on either side of BjPC1. BLAST analysis revealed that these marker sequences corresponded highly to A02 in B. juncea. They were mapped within a 33 kb genomic region on B. rapa A02 (corresponds to a 40 kb genomic region on B. juncea A02) that included three genes. Sequence BjuA008406, homologous to AtPES2 in Arabidopsis thaliana and Bra032956 in B. rapa, was the most likely candidate for BjPC1. These results should accelerate BjPC1 cloning and facilitate our understanding of the molecular mechanisms controlling B. juncea petal color.     

DNA taxonomy in the timber genus <Emphasis Type="Italic">Milicia</Emphasis>: evidence of unidirectional introgression in the West African contact zone

DNA-based techniques are helpful in characterising hybridisation patterns in plant species. To be efficient in disentangling species boundaries and interspecific gene flow, it is recommended to combine various methodologies and types of markers. Here, we used different analytical tools (algorithms implemented in Structure, Tess, NewHybrids and HIest, and the haploweb approach) and three nuclear genetic markers (7 nuclear simple sequence repeat loci (SSRs), 62 single-nucleotide polymorphism loci (SNPs) and a single-copy gene region, At103) to revisit hybridisation patterns in the commercially important African tree genus Milicia. Samples were collected in the natural ranges of Milicia regia and Milicia excelsa in West Africa. Using real data sets, simulated purebreds and hybrid genotypes, we found that SNPs yielded results more consistent than SSRs; outputs from the Bayesian and maximum-likelihood analyses differed significantly using the SSRs, whereas they were perfectly congruent using SNPs. A proportion of 12.4% hybrids were detected amongst the SNP genotype samples. A haploweb analysis of At103 gene sequences confirmed the existence of interspecific hybrids. There was also a clear evidence of advanced generations of hybrids (backcrossed individuals) but only towards M. regia. Although more investigation is required for understanding the mechanisms responsible for this asymmetric introgression, we suggest that it may be due to the differences in flowering time between species and between sexes, combined with a maternal inheritance of flowering time.     

Predictive capability of a leaf optical meter for determining leaf pigment status during senescence

We conducted an experiment to assess the predictive capability of a leaf optical meter for determining leaf pigment status of Acer mono Maxim., A. ginnala Maxim., Quercus mongolica Fisch., and Cornus alba displaying a range of visually different leaf colors during senescence. Concentrations of chlorophyll (Chl) a, Chl b, and total Chl [i.e., Chl (a+b)] decreased while the concentration of carotenoids (Car) remained relatively static for all species as leaf development continued from maturity to senescence. C. alba exhibited the lowest average concentration of Chl (a+b), Chl a, and Car, but the highest relative anthocyanin concentration, while Q. mongolica exhibited the highest Chl (a+b), Chl b, and the lowest relative anthocyanin concentration. A. mono exhibited the highest Chl a and Car concentrations. The relationships between leaf pigments and the values measured by the optical meter generally followed an exponential function. The strongest relationships between leaf pigments and optical measurements were for A. mono, A. ginnala, and Q. mongolica (R ² ranged from 0.64 to 0.95), and the weakest relationships were for C. alba (R ² ranged from 0.13 to 0.67). Moreover, optical measurements were more strongly related to Chl a than to Chl b or Chl (a+b). Optical measurements were not related to Car or relative anthocyanin concentrations. We predicted that weak relationships between leaf pigments and optical measurements would occur under very low Chl concentrations or under very high anthocyanin concentrations; however, these factors could not explain the weak relationship between Chl and optical measurements observed in C. alba. Overall, our results indicated that an optical meter can accurately estimate leaf pigment concentrations during leaf senescence — a time when pigment concentrations are dynamically changing — but that the accuracy of the estimate varies across species. Future research should investigate how species-specific leaf traits may influence the accuracy of pigment estimates derived from optical meters.     

Increased nitrogen deposition alleviated the adverse effects of drought stress on <Emphasis Type="Italic">Quercus variabilis</Emphasis> and <Emphasis Type="Italic">Quercus mongolica</Emphasis> seedlings

The plasticity response of Quercus variabilis and Quercus mongolica seedlings to combined nitrogen (N) deposition and drought stress was evaluated, and their performance in natural niche overlaps was predicted. Seedlings in a greenhouse were exposed to four N deposition levels (0, 4, 8, and 20 g N m^?2 year^?1) and two water levels (80 and 50 % field-water capacity). Plant traits associated with growth, biomass production, leaf physiology, and morphology were determined. Results showed that drought stress inhibited seedling performance, altered leaf morphology, and decreased fluorescence parameters in both species. By contrast increased N supply had beneficial effects on the nutritional status and activity of the PSII complex. The two species showed similar responses to drought stress. Contrary to the effects in Q. mongolica, N deposition promoted leaf N concentration, PSII activity, leaf chlorophyll contents, and final growth of Q. variabilis under well-watered conditions. Thus, Q. variabilis was more sensitive to N deposition than Q. mongolica. However, excessive N supply (20 g N m^?2 year^?1) did not exert any positive effects on the two species. Among the observed plasticity of the plant traits, plant growth was the most plastic, and leaf morphology was the least plastic. Therefore, drought stress played a primary role at the whole-plant level, but N supply significantly alleviated the adverse effects of drought stress on plant physiology. A critical N deposition load around 20 g N m^?2 year^?1 may exist for oak seedlings, which may more adversely affect Q. variabilis than Q. mongolica.     

Development of microsatellite markers for the carnivorous plant <Emphasis Type="Italic">Genlisea aurea</Emphasis> (Lentibulariaceae) using genomics data of NGS

Genlisea aurea A.St.-Hil. is a carnivorous plant endemic species to Brazil in the Lentibulariaceae family. Very few studies have addressed the genetic structure and conservation status of G. aurea and the Lentibulariaceae. Microsatellites markers are advantageous tools that can be employed to predict the vulnerability of Lentibulariaceae species. Therefore, the development of molecular markers focusing the population analyses of Genlisea for future genetic studies and conservation actions are essential. Thus, we developed simple sequence repeats (SSRs) based on in silico analyses of G. aurea draft genome assembly. We characterized 40 individuals from several populations and identified 12 loci that were polymorphic, with heterozygosity between 0.123 and 0.650. We demonstrated that the G. aurea SSR markers work cross-species in Genlisea filiformis, G. repens, G. tuberosa and G. violacea. These markers will be important for future population, phylogeographic and conservation studies in G. aurea and other Genlisea species.     

Long-term monitoring of saproxylic beetles from Mediterranean oak forests: an approach to the larval biology of the most representative species

Branches of Quercus species killed by Coraebus florentinus (Coleoptera, Buprestidae) are a chief resource for many saproxylic insects, mainly of the orders Coleoptera and Diptera, in the oak forests of the southern Iberian Peninsula. To investigate the biology of these species, a total of 127 dry oak branches that had been previously colonised by C. florentinus were collected and kept in the laboratory, in conditions comparable to the outdoor climate. For 4 years, the emergence of saproxylic insects from the branches was monitored. We obtained 651 individuals, belonging to 19 species of 6 families. Three buprestids (Anthaxia hungarica, A. millefolii and Agrilus angustulus) and one cerambycid (Chlorophorus ruficornis) made up 68% of the total abundance. Results on host tree preferences indicated that A. hungarica and C. ruficornis show more affinity to holm oaks (Q. ilex). Conversely, A. angustulus and A. hastulifer prefer cork oaks (Q. suber). Preimaginal stages have long durations, but vary in relation to the body size of species: smaller species such as A. angustulus and A. millefolii exhibit shorter larval time, reaching the maximum of emergences after 12 months monitoring, whereas larger species such as A. hungarica and C. ruficornis display a longer pre-adult period (3 and 4 years, respectively). The insects were found to be active in spring and summer and to have a balanced sex ratio in all of the species studied. Finally, our results also indicate the importance of long-term maintenance of these branches in the natural environment for the conservation of saproxylic biodiversity in the Iberian “dehesa”.     

Spatial pattern and association of tree species in a mixed <Emphasis Type="Italic">Abies holophylla</Emphasis>-broadleaved deciduous forest in Odaesan National Park

The mixed Abies holophylla-broadleaved deciduous forest is mature relative to other forest types in the midland of South Korea. The spatial distribution patterns of eight dominant canopy tree species were analyzed using Ripley’s K function. This study was conducted to clarify interspecific and intraspecific associations among growth stages and to interpret the coexistence mechanism among such species, by extension, to forecast their future. Disturbance-driven site heterogeneity has spatially separated disturbance-resistant Magnolia sieboldii from the other seven species. Spatial distribution of other species is affected by dispersal mechanisms and interspecific and intraspecific competition. These species were classified into three groups. The first group, composed of A. holophylla, Tilia amurensis, Acer pseudo-sieboldianum, and Quercus mongolica, was the most dominant and intraspecifically affinitive. Additionally, it seemed that they were established before the others. Q. mongolica and T. amurensis are poorly resistant to shade and are likely to be crowded out. In contrast, the other two species may continue, as they are highly resistant to shade and have high reproductivity. The second group was composed of Carpinus cordata, Acer tegmentosum, and Acer mono, i.e., late-successional species that wait for chances with shade tolerance and high reproductivity. These species are expected to occupy much of the Q. mongolica and T. amurensis space. M. sieboldii, i.e., the third group, were negatively related with other species and have dominated the valleys where intense disturbances are repeated. Understories have poor reproductivity, but a stationary population is expected to be maintained if canopy gaps are created by occasional disturbances.     

Generic reclassification and species boundaries in the rediscovered freshwater mussel ‘<Emphasis Type="Italic">Quadrula’ mitchelli</Emphasis> (Simpson in Dall, 1896)

The Central Texas endemic freshwater mussel, Quadrula mitchelli (Simpson in Dall, 1896), had been presumed extinct until relict populations were recently rediscovered. To help guide ongoing and future conservation efforts focused on Q. mitchelli we set out to resolve several uncertainties regarding its evolutionary history, specifically its unknown generic position and untested species boundaries. We designed a molecular matrix consisting of two loci (cytochrome c oxidase subunit I and internal transcribed spacer I) and 57 terminal taxa to test the generic position of Q. mitchelli using Bayesian inference and maximum likelihood phylogenetic reconstruction. We also employed two Bayesian species validation methods to test five a priori species models (i.e. hypotheses of species delimitation). Our study is the first to test the generic position of Q. mitchelli and we found robust support for its inclusion in the genus Fusconaia. Accordingly, we introduce the binomial, Fusconaia mitchelli comb. nov., to accurately represent the systematic position of the species. We resolved F. mitchelli individuals in two well supported and divergent clades that were generally distinguished as distinct species using Bayesian species validation methods, although alternative hypotheses of species delineation were also supported. Despite strong evidence of genetic isolation within F. mitchelli, we do not advocate for species-level status of the two clades as they are allopatrically distributed and no morphological, behavioral, or ecological characters are known to distinguish them. These results are discussed in the context of the systematics, distribution, and conservation of F. mitchelli.     

Species-specific alleles at a <Emphasis Type="Italic">β-</Emphasis>tubulin gene show significant associations with leaf morphological variation within <Emphasis Type="Italic">Quercus petraea</Emphasis> and <Emphasis Type="Italic">Q. robur</Emphasis> populations

Quercus petraea and Q. robur are largely sympatric oak species in western and central Europe and known for their intensive genetic exchange which has made the discovery of species-diagnostic markers a huge challenge. Various natural white oak populations (Q. petraea/Q. robur including mixed stands) were investigated for their variability and differentiation patterns at a β-tubulin gene (qutub8) in a European-wide survey. This gene was chosen as a possible candidate among loci subjected to selection and maintaining integrity between species. Two frequent alleles depicted as indels within qutub8’s first intron showed remarkably high interspecific genetic differentiation, with Weir and Cockerham’s theta per allele values ranging from 0.17 to 0.30 for one allele and from 0.04 to 0.19 for the other allele in such mixed oak stands where the multi-allelic qutub8 locus showed significant interspecific F _ST . For three mixed stands, qutub8’s F _ST significantly departed from the expected neutral differentiation patterns (F _ST ranging from 0.063 to 0.080 for this multi-allelic marker) and thus could be influenced by selection. Significant associations were found between genotypic variation and leaf dimensions as well as leaf structure patterns, after having accounted for species and stand effects. Qutub8 represents a locus that exhibits significant species differentiation and is linked to morphological discriminant traits. Consequently, qutub8 likely contributes to species divergence within the European white oak complex.     

Genetic variation and differentiation in populations of Japanese emperor oak <Emphasis Type="Italic">Quercus dentata</Emphasis> Thunb. and Mongolian oak <Emphasis Type="Italic">Quercus mongolica</Emphasis> Fisch. ex Ledeb.) in the south of the Russian Far East

Allozyme variation of Japanese emperor oak Quercus dentata Thunb. and Mongolian oak Quercus mongolica Fisch. ex Ledeb.) was examined in 11 populations of these species from southern Primorye. Analysis of 18 loci showed that in these populations, 66.7% of genes of Mongolian oak are polymorphic, the number of alleles per locus being 2.28. In Japanese emperor oak, these parameters were respectively 59.8 and 2.36%. The observed heterozygosity in both species did not differ from the expected values, constituting 0.198 in Japanese emperor oak and 0.161 in Mongolian oak. The Nei’s distance between Quercus mongolica and Q. dentata was 0.053. The main contribution to the species differentiation is made by loci Lap-1, Idh-1, Pgm-1, and Ndh-1, although none of them is diagnostic. The Japanese emperor oak and Mongolian oak populations formed separate clusters in an UPGMA dendrogram. Taking into account morphological and ecological isolation of the species, we suggest that the differences in gene frequencies may reflect selection acting in favor of adaptation to different growth conditions and counteracting between-species hybridization.     

In silico polymorphic novel SSR marker development and the first SSR-based genetic linkage map in pistachio

Simple sequence repeats (SSRs) are co-dominant markers, and are very useful in constructing consensus maps in heterozygous perennial plant species like pistachio. Pistacia vera L. is the only cultivated species in the genus Pistacia. It is dioecious with a haploid chromosome count of n =?15. Saturated genetic linkage maps can be a reference to identify markers linked to economically important phenotypic traits that could be useful for early breeding and selection programs. Therefore, this study aimed to develop polymorphic SSR markers in silico and to construct the first SSR-based genetic linkage map in pistachio. The DNA sequences of three cultivars (Siirt, Ohadi, and Bagyolu) of P. vera and one genotype belonging to P. atlantica (Pa-18) were obtained by next-generation sequencing, and 625 polymorphic SSR loci were identified from 750 screened in silico polymorphic SSR primer pairs. The novel SSRs were used to construct SSR-based genetic linkage maps in pistachio along with published SSRs in Siirt × Bagyolu F1 population. Most (71.4%) of the SSRs were common markers that were used to construct consensus and parental maps spanning 15 linkage groups (LGs). A total of 384, 317, and 341 markers were mapped in the consensus, female, and male genetic maps with total lengths of 1511.3, 1427.0, and 1453.4 cM, respectively. The large number of SSR markers discovered and the first SSR-based genetic linkage map constructed in this study will be useful for anchoring loci for map integration, and will facilitate marker-assisted selection efforts for important horticultural traits in the genus Pistacia.     

Construction of genetic transformation system of <Emphasis Type="Italic">Salix mongolica</Emphasis>: in vitro leaf-based callus induction,adventitious buds differentiation,and plant regeneration

Songnen meadow grassland is a typical saline-alkaline land majorly comprised of carbonate soil. Salix mongolica, a woody species with high adaptability to carbonate soil, is an important supplementary feed in the grassland. Therefore, it is necessary to cultivate new varieties of S. mongolica by using genetic engineering methods to reveal the functions of the plant’s related genes and to construct a plant regeneration and genetic transformation system. In this study, we used leaves of S. mongolica as the explants for induction of leaf-based callus, differentiation of adventitious buds and rooting of adventitious by adding different ratios of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzyl aminopurine and naphthaleneacetic acid into the Murashige and Skoog medium. Under the screening conditions of 7.5 mg L^?1 hygromycin B and transformation period of 2–5 min using a specific Agrobacterium containing pCXSN-gus plasmids infection concentration (OD_λ600?=?0.5), we obtained transgenic strains. PCR detected exogenous gus gene integrated into the chromosome of S. mongolica, Southern blot analysed the T0 transgenic strains single copy inserted into the chromosome, Northern hybridization signals indicated that gus gene mRNA was expressed in the five contemporary transgenic strains. The infected callus, adventitious buds, and regenerated plants displayed a blue color through detection by GUS staining, which reflected the activity of ß-glucuronidase enzyme. This result demonstrated the successful establishment of an Agrobacterium-mediated genetic transformation system from the callus (S. mongolica leaf as a transformation receptor).     

Reconstruction of molecular phylogeny of closely related <Emphasis Type="Italic">Amorphophallus</Emphasis> species of India using plastid DNA marker and fingerprinting approaches

Plastid DNA markers sequencing and DNA fingerprinting approaches were used and compared for resolving molecular phylogeny of closely related, previously unexplored Amorphophallus species of India. The utility of individual plastid markers namely rbcL, matK, trnH–psbA, trnLC–trnLD, their combined dataset and two fingerprinting techniques viz. RAPD and ISSR were tested for their efficacy to resolves Amorphophallus species into three sections specific clades namely Rhaphiophallus, Conophallus and Amorphophallus. In the present study, sequences of these four plastid DNA regions as well as RAPD and ISSR profiles of 16 Amorphophallus species together with six varieties of two species were generated and analyzed. Maximum likelihood and Bayesian Inference based construction of phylogenetic trees indicated that among the four plastid DNA regions tested individually and their combined dataset, rbcL was found best suited for resolving closely related Amorphophallus species into section specific clades. When analyzed individually, rbcL exhibited better discrimination ability than matK, trnH–psbA, trnLC–trnLD and combination of all four tested plastid markers. Among two fingerprinting techniques used, the resolution of Amorphophallus species using RAPD was better than ISSR and combination of RAPD +ISSR and in congruence with resolution based on rbcL.     

Phylogeography and evolution of two closely related oak species (<Emphasis Type="Italic">Quercus</Emphasis>) from north and northeast China

Orographic and climatic influences during the Pleistocene have had a crucial role on interspecific divergence and population demography during speciation. However, associations between demographic histories of closely related species and related climatic events, especially in north and northeast China, are still underexplored. Genetic analyses with four chloroplast DNA and two nuclear genes and species distribution modeling were used for two closely related oak species (Quercus liaotungensis and Quercus mongolica) to test if their interspecific divergence and phylogeographical histories were possibly related to the Pleistocene-era climatic events. Potential divergence of the two oak species was estimated at about 0.92–2.15 Ma. Species distribution models and genetic data showed varying phylogeographical histories and spatial population structures between the two oaks, leading to different patterns of interspecific gene flow between the chloroplast and nuclear genes. The results indicate that speciation event between the two species is recent and may have been triggered by geological and climatic fluctuations linked to the upheavals of the Qinghai-Tibetan Plateau at the Pliocene/Pleistocene boundary. The two closely related oaks possess varying population demography during the interglacial-glacial climatic oscillations of the Quaternary, probably due to the various niche adaptations among different distribution ranges across their species trajectories.     

Three new species of <Emphasis Type="Italic">Russula</Emphasis> from South China

Russula lotus, R. nivalis, and R. purpureoverrucosa are proposed here as new taxa based on morphological and molecular evidences. The new species are described with illustration photographs and line drawings, and compared against related species. Morphologically, R. lotus (subgenus Heterophyllidia, section Heterophyllae, subsection Cyanoxanthinae) is characterized by a medium-sized basidioma with a pale pink to purplish pink pileus whose center area is yellowish white, white to cream white lamellae occasionally forked with lamellulae, a cream white smooth stipe, broadly ellipsoid to ellipsoid basidiospores ornamented with disconnected amyloid warts and inamyloid suprahilar plage, dispersed sulphovanillin (SV)-negative pileocystidia, and the pileipellis with suprapellis cells claw-assembled. Russula nivalis (subgenus Russula, section Russula, subsection Russula) is characterized by a very small pure white basidioma with a pileus 7–12 mm in diameter, abundant clavate pileocystidia and caulocystidia changing purplish red in SV, and broadly ellipsoidal to ellipsoid basidiospores ornamented with strongly amyloid warts and ridges interconnected by fine lines in an uncompleted or completed reticulum, mostly with inamyloid suprahilar plage. Russula purpureoverrucosa (subgenus Incrustatula, section Lilaceinae, subsection Lilaceinae) is characterized by a medium-sized basidioma with a red to grayish magenta pileus slightly areolate in small irregular warts from center to margin, a stipe with the same color and warts as the pileus, white to cream white occasionally forked lamellae with lamellulae, broadly ellipsoidal to ellipsoid basidiospores ornamented with amyloid warts and ridges rarely connected, abundant clavate pleurocystidia covered with thick yellowish incrustations, and the pileipellis with suprapellis cells a typical trichoderm, some of which covered with yellowish incrustations, pileocystidia absent. Phylogenetic analysis of nucleotide sequences of the internal transcribed spacer (ITS) region provided further evidence that the described species belong to the subsections above respectively, and represent new taxa.