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Tropospheric ozone (O3) is a phytotoxic air pollutant adversely affecting plant growth. High O3 exposures are often concurrent with summer drought. The effects of both stresses on plants are complex, and their interactions are not yet well understood. Here, we investigate whether drought can mitigate the negative effects of O3 on plant physiology and growth based on a meta‐analysis. We found that drought mitigated the negative effects of O3 on plant photosynthesis, but the modification of the O3 effect on the whole‐plant biomass by drought was not significant. This is explained by a compensatory response of water‐deficient plants that leads to increased metabolic costs. Relative to water control condition, reduced water treatment decreased the effects of O3 on photosynthetic traits, and leaf and root biomass in deciduous broadleaf species, while all traits in evergreen coniferous species showed no significant response. This suggested that the mitigating effects of drought on the negative impacts of O3 on the deciduous broadleaf species were more extensive than on the evergreen coniferous ones. Therefore, to avoid over‐ or underestimations when assessing the impact of O3 on vegetation growth, soil moisture should be considered. These results contribute to a better understanding of terrestrial ecosystem responses under global change. Summary statement: Drought mitigated the negative effects of elevated O3 on some photosynthesis‐related parameters but not on the growth of the whole plant. The mitigation effects of drought on O3‐induced reductions in photosynthesis and biomass were greater in the deciduous species than in the evergreen species. [ABSTRACT FROM AUTHOR]

In the 1990s, a sampling network for the biomonitoring of forests using epiphytic lichen diversity was established in the eastern Iberian Peninsula. This area registered air pollution impacts by winds from the Andorra thermal power plant, as well as from photo-oxidants and nitrogen depositions from local and long-distance transport. In 1997, an assessment of the state of lichen communities was carried out by calculating the Index of Atmospheric Purity. In addition, visible symptoms of morphological injury were recorded in nine macrolichens pre-selected by the speed of symptom evolution and their wide distribution in the territory. The thermal power plant has been closed and inactive since 2020. During 2022, almost 25 years later, seven stations of this previously established biomonitoring were revaluated. To compare the results obtained in 1997 and 2022, the same methodology was used, and data from air quality stations were included. We tested if, by integrating innovative methodologies (NIRS) into biomonitoring tools, it is possible to render an integrated response. The results displayed a general decrease in biodiversity in several of the sampling plots and a generalised increase in damage symptoms in the target lichen species studied in 1997, which seem to be the consequence of a multifactorial response. [ABSTRACT FROM AUTHOR]

Context: Ozone concentrations near the land surface are rising in Asia while they are declining or stagnating in Europe and North America. Ozone is the most widespread air pollutant negatively affecting vegetation, and its increased concentrations pose a major threat to food quality and production and other ecosystem services in Asia.Method: In this review, we provide an overview of scientific challenges in the impacts of ozone pollution on Asian vegetation, and synthesize the challenges toward mitigation of the impacts.Result: We argue that new policy initiatives need to seek both reduction of ozone levels and enhancement of plant tolerance to ozone to maintain food quality and ensure food supplies.Conclusion: The scientific advancements must be transferred to actions by two types of institutions: a) environmental agencies for reducing ozone levels and b) agricultural research institutions for enhancing plant tolerance to ozone. In connecting the scientific advancements with the institutional actions, scientists in Asian countries should play the key role taking advantages of interdisciplinary and international collaborations. [ABSTRACT FROM AUTHOR]

The cover image is based on the Original Article Drought mitigates the adverse effects of O3 on plant photosynthesis rather than growth: A global metaanalysis considering plant functional types by Bo Shang et al., https://doi.org/10.1111/pce.14808..By Bo Shang; Evgenios Agathokleous; Vicent Calatayud; Jinlong Peng; Yansen Xu; Shuangjiang Li; Shuo Liu and Zhaozhong FengReported by Author; Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

Elevated concentrations of ground‐level ozone (O3) and atmospheric nitrogen (N) deposition occur concurrently. The negative effects of elevated O3 on plants have been widely studied and are well understood nowadays. However, how the effects of elevated O3 on plants may be driven by N deposition remains an unsolved puzzle.We conducted a meta‐analysis and showed that the negative effects of elevated O3 on photosynthesis, stomatal conductance, growth and biomass production of semi‐natural and natural vegetation may remain unchanged by N deposition in the coming future under realistic increases in O3 concentrations (+20 to 40 ppb) and N deposition (up to 60 kg ha−1 year−1). The negative effect of elevated O3 on chlorophyll content is offset by soil N addition; however, the negative effect on biomasses is not offset by soil N addition.Across functional groups and O3 levels, N addition exacerbated O3 effects on root when N increased from 0–10 kg N ha−1 year−1 to 11–30 kg N ha−1 year−1. However, an analysis as per the plant functional group revealed that such a N‐dependent O3 effect was significant only in perennial non‐woody plants, and was non‐significant when only realistic increases in O3 concentrations were considered. Likewise, N addition appeared to exacerbate O3‐negative effects on photosynthesis of trees when N increased from 0–30 kg N ha−1 year−1 to >60 kg N ha−1 year−1; however, this effect was significant only when realistic increases in O3 concentrations were considered.The results suggest potential error in the current estimates of the overall O3 impacts on plants due to no consideration of soil N availability, and encourage further studies on the interaction of O3 and N availability that will permit more robust analyses in the future. Elevated O3 will likely remain a persistent agricultural and ecological issue independently of N deposition. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

A stomatal ozone (O 3) flux-response relationship for relative yield of maize was established by parameterizing a Jarvis stomatal conductance model. For the function (f VPD) describing the limitation of stomatal conductance by vapor pressure deficit (VPD, kPa), cumulative VPD during daylight hours was superior to hourly VPD. The latter function is proposed as a methodological improvement of this multiplicative model when stomatal conductance peaks during the morning and it is reduced later as it is the case of maize in this experiment. The model agreed relatively well with the measured stomatal conductance (R2 = 0.63). Based on the comparison of R2 values of the response functions, POD 6 (Phytotoxic Ozone Dose over an hourly threshold 6 nmol m−2 s−1) and AOT40 (accumulated hourly O 3 concentrations over a threshold of 40 ppb) performed similarly. The critical levels based on POD 6 and AOT40 for 5% reduction in maize yield were 1.17 mmol m−2 PLA and 8.70 ppm h, respectively. In comparison with other important crops, the ranking of sensitivity of maize strongly differed depending on the O 3 metric used, AOT40 or POD 6. The newly proposed response functions are relevant for O 3 risk assessment for this crop in Asia. Image 1 • The Jarvis stomatal conductance model of maize was parameterized. • Cumulative VPD during daylight hours was superior to hourly VPD for f VPD. • An O 3 flux-yield response relationship was developed for maize for the first time. • The performance of O 3 exposure- and flux–based approaches was similar. [ABSTRACT FROM AUTHOR]

Wheat is a major staple food and its sensitivity to the gas pollutant ozone (O3) depends on the cultivar. However, few chamber-less studies assessed current ambient O3 effects on a large number of wheat cultivars. In this study, we used ethylenediurea (EDU), an O3 protectant whose protection mechanisms are still unclear, to test photosynthetic pigments, gas exchange, antioxidants, and yield of 15 cultivars exposed to 17.4 ppm h AOT40 (accumulated O3 over an hourly concentration threshold of 40 ppb) over the growing season at Beijing suburb, China. EDU significantly increased light-saturated photosynthesis rate (Asat), photosynthetic pigments (i.e., chlorophyll and carotenoid), and total antioxidant capacity, while reduced malondialdehyde and reduced ascorbate contents. In comparison with EDU-treated plants (control), plants treated with water (no protection from ambient O3) significantly decreased yield, weight of 1000 grains, and harvest index by 20.3%, 15.1%, and 14.2%, respectively, across all cultivars. There was a significant interaction between EDU and cultivars in all tested variables with exception of Asat, chlorophyll, and carotenoid. The cultivar-specific sensitivity to O3 was ranked from highly sensitive (> 25% change) to less sensitive (< 10% change) by comparing the difference of the average grain yield of plants applied with and without EDU. Neither stomatal conductance nor antioxidant capacity contributed to the different response of the cultivars to EDU, suggesting that another mechanism contributes to the large variation in response to O3 among cultivars. Generally, the results indicate that present O3 concentration is threatening wheat production in Northern China, highlighting the urgent need for policy-making actions to protect this critical staple food. [ABSTRACT FROM AUTHOR]

Five winter wheat cultivars were exposed to ambient (A-O 3 ) and elevated (E-O 3 , 1.5 ambient) O 3 in a fully open-air fumigation system in China. Ozone exposure- and flux based response relationships were established for seven physiological variables related to photosynthesis. The performance of the fitting of the regressions in terms of R 2 increased when second order regressions instead of first order ones were used, suggesting that effects of O 3 were more pronounced towards the last developmental stages of the wheat. The more robust indicators were those related with CO 2 assimilation, Rubisco activity and RuBP regeneration capacity ( A sat , J max and V c max ), and chlorophyll content ( Chl ). Flux-based metrics (POD y , Phytotoxic O 3 Dose over a threshold y nmol O 3 m − 2 s − 1 ) predicted slightly better the responses to O 3 than exposure metrics (AOTX, Accumulated O 3 exposure over an hourly Threshold of X ppb) for most of the variables. The best performance was observed for metrics POD 1 ( A sat , J max and V c max ) and POD 3 ( Chl ). For this crop, the proposed response functions could be used for O 3 risk assessment based on physiological effects and also to include the influence of O 3 on yield or other variables in models with a photosynthetic component. [ABSTRACT FROM AUTHOR]

The effects of elevated ozone on C (carbon), N (nitrogen) and P (phosphorus) ecological stoichiometry and nutrient resorption in different organs including leaves, stems and roots were investigated in poplar clones 546 ( P. deltoides cv. ‘55/56’ × P. deltoides cv. ‘Imperial’) and 107 ( P. euramericana cv. ‘74/76’) with a different sensitivity to ozone. Plants were exposed to two ozone treatments, NF (non-filtered ambient air) and NF60 (NF with targeted ozone addition of 60 ppb), for 96 days in open top chambers (OTCs). Significant ozone effects on most variables of C, N and P ecological stoichiometry were found except for the C concentration and the N/P in different organs. Elevated ozone increased both N and P concentrations of individual organs while for C/N and C/P ratios a reduction was observed. On these variables, ozone had a greater effect for clone 546 than for clone 107. N concentrations of different leaf positions ranked in the order upper > middle > lower, showing that N was transferred from the lower senescent leaves to the upper ones. This was also indicative of N resorption processes, which increased under elevated ozone. N resorption of clone 546 was 4 times larger than that of clone 107 under ambient air (NF). However, elevated ozone (NF60) had no significant effect on P resorption for both poplar clones, suggesting that their growth was only limited by N, while available P in the soil was enough to sustain growth. Understanding ecological stoichiometric responses under ozone stress is crucial to predict future effects on ecological processes and biogeochemical cycles. [ABSTRACT FROM AUTHOR]

Current ozone (O 3 ) levels are high enough to negatively affect vegetation and may become worse in the future. Ozone risk assessments have recently shifted from exposure-based to flux-based metrics. Modeling stomatal O 3 fluxes requires hourly O 3 and meteorological data, which are not always available. Large datasets of O 3 concentrations measured with passive samplers exist worldwide, and usually provide weekly to monthly means. We tested the suitability of using aggregated data instead of hourly data for O 3 flux calculations with 3-year time series of O 3 data from 24 Spanish air quality stations. Five different approaches and three different parameterizations were tested. Ozone-averaged values in combination with hourly meteorological data provided the most robust estimates of accumulated O 3 fluxes (Phytotoxic Ozone Dose with no threshold, POD0), and the median of the absolute percent error (MAPE) due to aggregation came close to 5%. Aggregations from 1 week to 1 month yielded similar errors, which is important in the cost-efficiency terms of the chosen passive sampler exposure periodicity. One major limitation of these approaches is that they are not suitable for high POD thresholds, and that accuracy of the measurements with passive samplers has to be strictly assured in order to finally obtain acceptable errors. A combination of meteorological data and O 3 passive sampler measurements may be used to estimate O 3 fluxes at remote forest sites as a valuable risk assessment tool. [ABSTRACT FROM AUTHOR]

The combined effects of ozone (O3) and drought on isoprene emission were studied for the first time. Young hybrid poplars (clone 546, Populus deltoides cv. 55/56 x P. deltoides cv. Imperial) were exposed to O3 (charcoal-filtered air, CF, and non-filtered air +40 ppb, E-O3) and soil water stress (well-watered, WW, and mild drought, MD, one-third irrigation) for 96 days. Consistent with light-saturated photosynthesis ( Asat), intercellular CO2 concentration ( Ci) and chlorophyll content, isoprene emission depended on drought, O3, leaf position and sampling time. Drought stimulated emission (+38.4%), and O3 decreased it (−40.4%). Ozone increased the carbon cost per unit of isoprene emission. Ozone and drought effects were stronger in middle leaves (13th-15th from the apex) than in upper leaves (6th-8th). Only Asat showed a significant interaction between O3 and drought. When the responses were up-scaled to the entire-plant level, however, drought effects on total leaf area translated into around twice higher emission from WW plants in clean air than in E-O3. Our results suggest that direct effects on plant emission rates and changes in total leaf area may affect isoprene emission from intensively cultivated hybrid poplar under combined MD and O3 exposure, with important feedbacks for air quality. [ABSTRACT FROM AUTHOR]

Ozone (O3) sensitivity varies greatly among plant species. Leaf traits such as stomatal conductance, antioxidant capacity and leaf morphology and anatomy may play important roles in controlling this variation, but the relative contributions of each trait remain elusive. In this study, we examined the differences in O3 sensitivity among 29 deciduous and evergreen woody species used for urban greening in China in an open-top chamber experiment. Elevated O3 caused visible injury and reductions in net photosynthesis, and these effects differed significantly among species. The deciduous species Sorbaria sorbifolia, Hibiscus syriacus and Fraxinus chinensis were the most sensitive, while evergreen species ranked among the most tolerant. O3 sensitivity was linked to both low leaf mass per area (LMA) and low leaf area-based antioxidant levels, but not to variation in leaf mass-based antioxidant levels or stomatal conductance. The well-known and easily measured leaf trait LMA thus represents a potentially useful metric for O3 risk assessment and for selecting appropriate species for urban greening in O3-polluted areas. [ABSTRACT FROM AUTHOR]

Fast urbanization has led to ozone (O 3 ) being the main pollutant in summer in most of China. To assess future ground-level O 3 effects on the service of urban greening species and clarify the underlying mechanism of O 3 damage, four common urban greening species, Ailanthus altissima (AA), Fraxinus chinensis (FC), Platanus orientalis (PO) and Robinia pseudoacacia (RP) were exposed to non-filtered air (NF) and to elevated O 3 (E-O 3 ) in open-top chambers. E-O 3 induced visible injury in all species as well as microscopic alterations such as collapse of the palisade parenchyma cells, callose accumulation, or chloroplast and mitochondrial accelerated senescence. E-O 3 significantly reduced light-saturated CO 2 assimilation ( A sat ), the maximum activity of Rubisco ( Vc max ), the maximum electron transport rate ( J max ), and fluorescence parameters such as the quantum yield of noncyclic electron transport ( ϕ PSII ), and the quenching of photochemical efficiency of PSII ( q P). It also increased total antioxidant capacity, phenolics and ascorbate contents. No significant interaction between O 3 and species was found in photosynthetic performance and antioxidant systems, suggesting that the four species selected were sensitive to O 3 . Of all four species, AA was the most sensitive species due to a combination of earlier injury onset, anatomical features, lower antioxidant responses and higher stomatal conductance. The sensitivity of tree species to O 3 is a factor to be considered for urban greening. Ozone may affect important urban forest ecosystem services by reducing CO 2 assimilation. [ABSTRACT FROM AUTHOR]

Four genotypes of snap bean ( Phaseolus vulgaris L.) were selected to study the effects of ambient ozone concentration at a cropland area around Beijing by using 450 ppm of ethylenediurea (EDU) as a chemical protectant. During the growing season, the 8 h (9:00–17:00) average ozone concentration was very high, approximately 71.3 ppb, and AOT40 was 29.0 ppm.h. All genotypes showed foliar injury, but ozone-sensitive genotypes exhibited much more injury than ozone-tolerant ones. Compared with control, EDU significantly alleviated foliar injury, increased photosynthesis rate and chlorophyll a fluorescence, Vc max and J max , and seed and pod weights in ozone-sensitive genotypes but not in ozone-tolerant genotypes. EDU did not significantly affect antioxidant contents in any of the genotypes. Therefore, EDU effectively protected sensitive genotypes from ambient ozone damage, while protection on ozone-tolerant genotypes was limited. EDU can be regarded as a useful tool in risk assessment of ambient ozone on food security. [ABSTRACT FROM AUTHOR]

Despite the high ozone levels measured in China, and in Beijing in particular, reports of ozone-induced visible injury in vegetation are very scarce. Visible injury was investigated on July and August 2013 in the main parks, forest and agricultural areas of Beijing. Ozone injury was widespread in the area, being observed in 28 different species. Symptoms were more frequent in rural areas and mountains from northern Beijing, downwind from the city, and less frequent in city gardens. Among crops, injury to different types of beans (genera Phaseolus, Canavalia and Vigna) was common, and it was also observed in watermelon, grape vine, and in gourds. Native species such as ailanthus, several pines and ash species were also symptomatic. The black locust, the rose of Sharon and the Japanese morning glory were among the injured ornamental plants. Target species for broader bio-monitoring surveys in temperate China have been identified. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lichens support the quantification of empirical critical loads for ecosystems at large scales. [•] It was possible to determine a nitrogen critical load of 2.4 kgha− 1 yr− 1. [•] The correlations between lichens and pollutants were higher in nemoral-boreal conifer forests. [Copyright &y& Elsevier]

Ozone effects on the perennial forb Lamottea dianae were studied in an open-top chamber experiment. Ozone was found to induce reductions in CO2 assimilation and water use efficiency in the leaves of this species. These reductions were mainly related to a decline in the in vivo CO2 fixation capacity of Rubisco (V c,max ), rather than to stomatal limitations or photoinhibitory damage (F v :F m ). In addition to chloroplast degeneration, other observed effects were callose accumulation, formation of pectinaceous wart-like cell wall exudates and phloem alterations. Moreover, ozone exposure significantly reduced root dry biomass. The possible relevance of these adverse effects for Mediterranean forbs is commented. These results show that endemic plants can be very sensitive to ozone, suggesting that risks associated with this pollutant should be taken into account for conservation purposes. [Copyright &y& Elsevier]

Plants of one evergreen oak (Quercus ilex) and three deciduous oaks (Q. faginea, with small leaves; Q. pyrenaica and Q. robur, with large leaves) were exposed both to filtered air and to enhanced ozone levels in Open-Top Chambers. Q. faginea and Q. pyrenaica were studied for the first time. Based on visible injury, gas exchange, chlorophyll content and biomass responses, Q. pyrenaica was the most sensitive species, and Q. ilex was the most tolerant, followed by Q. faginea. Functional leaf traits of the species were related to differences in sensitivity, while accumulated ozone flux via stomata (POD1.6) partly contributed to the observed differences. For risk assessment of Mediterranean vegetation, the diversity of responses detected in this study should be taken into account, applying appropriate critical levels. [Copyright &y& Elsevier]

Plant responses to enhanced ozone levels have been studied in two pairs of evergreen-deciduous species (Pistacia terebinthus vs. P. lentiscus; Viburnum lantana vs. V. tinus) in Open Top Chambers. Ozone induced widespread visible injury, significantly reduced CO2 assimilation and stomatal conductance (gs ), impaired Rubisco efficiency and regeneration capacity (V c,max, J max) and altered fluorescence parameters only in the deciduous species. Differences in stomatal conductance could not explain the observed differences in sensitivity. In control plants, deciduous species showed higher superoxide dismutase (SOD) activity than their evergreen counterparts, suggesting metabolic differences that could make them more prone to redox imbalances. Ozone induced increases in SOD and/or peroxidase activities in all the species, but only evergreens were able to cope with the oxidative stress. The relevancy of these results for the effective ozone flux approach and for the current ozone Critical Levels is also discussed. [Copyright &y& Elsevier]

Abstract: Ozone damage on trees leaves no residue that can be detected analytically; therefore visible assessment is the only easily detectable method for collecting evidence. Here we present an evaluation of an assessment method using damaged detected on trees grown in commercial tree nurseries. The extent of visible ozone injury to susceptible species was investigated on a total of 95 species across 13 nurseries, over four European countries during the 2006 season. Commercial nurseries were chosen because nurseries stock a wide range of accessible, susceptible species which are irrigated when necessary and therefore represent the optimum conditions for assessment of potential risk. Ozone climate at each site was characterised using a combination of passive and active samplers to estimate the accumulated ozone exposure over a threshold of 40ppb (AOT40). Meteorological and ozone monitoring data were used to calculate cumulative ozone flux using the DO3SE model (). Ozone injury was observed in all countries demonstrating that the impacts of ozone are not restricted to countries with higher ozone concentrations; the longer day-length, higher moisture availability and cooler conditions in northern Europe resulted in a greater potential for ozone uptake. Further use of commercial nurseries as an important, unofficial, bioindicator network is warranted. [ABSTRACT FROM AUTHOR]

Ozone-like visible injury was detected on Hibiscus syriacus plants used as ornamental hedges. Weekly spray of the antiozonant ethylenediurea (EDU, 300ppm) confirmed that the injury was induced by ambient ozone. EDU induced a 75% reduction in visible injury. Injury was more severe on the western than on the eastern exposure of the hedge. This factor of variability should be considered in ozone biomonitoring programmes. Seeds were collected and seedlings were artificially exposed to ozone in filtered vs. not-filtered (+30ppb) Open-Top Chambers. The level of exposure inducing visible injury in the OTC seedlings was lower than that in the ambient-grown hedge. The occurrence of visible injury in the OTC confirmed that the ozone sensitivity was heritable and suggested that symptomatic plants of this deciduous shrub population can be successfully used as ozone bioindicators. EDU is recommended as a simple tool for diagnosing ambient ozone visible injury on field vegetation. [Copyright &y& Elsevier]

Zwackhiomyces cervinae Calat., Triebel & Perez-Ortega is described as new to science from Spain and Iran. This lichenicolous species grows on the lateral side of the squamules of Acarospora cervina, and it is characterized by its relatively large ascospores, which are brown when overmarure. It is compared with several Zwackhiomyces species and with other taxa sharing some of its characters. A key to all the known species of the genus is also provided. [ABSTRACT FROM AUTHOR]

Monitoring of forest condition and ozone (O3) at 83 sites in France, Italy, Luxenbourg, Spain and Switzerland resulted in a number of findings in relation to the knowledge of O3 exposure (concentration and cumulative AOT40), feasibility of the assessment of stomatal O3 flux and relationships between O3 and crown defoliation of beech and visible symptoms on native vegetation. However, the project provides evidence of issues to be addressed within the current monitoring system (data quality, validation sites and response indicators) and indications as to how the monitoring of O3 risk in the context of an effect-oriented monitoring program can be improved. [Copyright &y& Elsevier]

Abstract: Urban atmospheres contain complex mixtures of air pollutants including mutagenic and carcinogenic substances such as benzene, diesel soot, heavy metals and polycyclic aromatic hydrocarbons. In the frame of a European network for the assessment of air quality by the use of bioindicator plants, the Tradescantia micronucleus (Trad-MCN) test was applied to examine the genotoxicity of urban air pollution. Cuttings of Tradescantia clone #4430 were exposed to ambient air at 65 monitoring sites in 10 conurbations employing a standardised methodology. The tests revealed an elevated genotoxic potential mainly at those urban sites which were exposed to severe car traffic emissions. This bioassay proved to be a suitable tool to detect local ‘hot spots’ of mutagenic air pollution in urban areas. For its use in routine monitoring programmes, however, further standardisation of cultivation and exposure techniques is recommended in order to reduce the variability of results due to varying environmental conditions. [Copyright &y& Elsevier]

Lichenostigma radicans Calat. & Barreno, a lichenicolous fungus growing on vagrant Aspicilia species, is described as new to science from Spain. It is superficially similar to L. maureri, with cushion-like ascomata, but differing mainly by its ascomata connected at their base to immersed, brown, vegetative hyphae. Comments on the variability of iodine reactions of asci and ascospore walls, and on an associated conidial fungus with small bacilliform conidia, are given for L. maureri. [Copyright &y& Elsevier]

The morphology, anatomy, ecology and distribution of Buellia tesserata and Dimelaena radiata are discussed. New data on their chemistry are given. The present study reveals a very close relationship between both taxa and consequently their different generic position is questioned. Buellia fimbriata is reduced to synonymy with Buellia tesserata. [Copyright &y& Elsevier]

Comments on and a key to the 13 Polycoccum species known in Spain are presented, including synopses of their world distributions. Amongst these is P. rubellianae sp. nov., a lichenicolous fungus growing on thalli of Caloplaca rubelliana in eastern Spain (Valencia). It has relatively small ascomata, the lower part pale brown, and also small ascospores which are coarsely verrucose and have a thick gelatinous sheath when young. The new species is associated with a Phoma-like anamorph. The identity and systematic position of P. opulentum requires further study as the name has been applied to different species, and the occurrence of P. marmoratum in Spain is in need of confirmation. The Spanish record of P. arnoldii on Lecania cyrtella probably refers to another yet undescribed species. [Copyright &y& Elsevier]