a b s t r a c tThe IUCN Red List is the most useful list of species that are at risk for extinction worldwide, as it relies on a number of objective criteria. Nevertheless, there is a taxonomic bias that excludes species with small body sizes, narrow distribution ranges and low dispersal abilities, which constitute the vast majority of the planet's biota, particularly local endemics.By evaluating each IUCN criterion separately, we (i) identify the shortcomings for invertebrate applications, (ii) explain how risk categories may be wrongly applied due to inapplicable and/or misleading thresholds, (iii) suggest alternative ways of applying the existing criteria in a more realistic way and (iv) suggest possible new criteria that were not considered in the current evaluation framework but that could allow a more comprehensive and effective assessment of invertebrates.By adapting the criteria to rely more explicitly on the Area of Occupancy and the Extent of Occurrence, their respective trends and by using ecological modelling methods, the criteria's applicability would be increased. The change in some thresholds or, eventually, the creation of sub-categories would further increase their adequacy. Additionally, co-extinction could be introduced as an explicit part of the classification process.As a case study, we evaluated 48 species of Azorean arthropods and Iberian spiders according to the current criteria. More than one-quarter (27%) of all evaluated species were classified as Critically Endangered, 19% as Endangered, 6% as Vulnerable and 8% as Least Concern. The remaining 40% did not have enough data to reach a classification.

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Past climatic shifts have played a major role in generating and shaping biodiversity. Quaternary glacial cycles are the better known examples of dramatic climatic changes endured by ecosystems in temperate regions. Although still a matter of debate, some authors suggest that glaciations promoted speciation. Here we investigate the effect of past climatic changes on the diversification of the ground‐dwelling spider genus Harpactocrates, distributed across the major mountain ranges of the western Mediterranean. Concatenated and species‐tree analyses of multiple mitochondrial and nuclear loci, combined with the use of fossil and biogeographic calibration points, reveal a Miocene origin of most nominal species, but also unravel several cryptic lineages tracing back to the Pleistocene. We hypothesize that the Miocene Climatic Transition triggered major extinction events in the genus but also promoted its subsequent diversification. Under this scenario, the Iberian mountains acted as an island‐like system, providing shelter to Harpactocrates lineages during the climate shifts and favouring isolation between mountain ranges. Quaternary glacial cycles contributed further to the diversification of the group by isolating lineages in peripheral refugia within mountain ranges. In addition, we recovered some unique biogeographic patterns, such as the colonization of the Alps and the Apennines from the Iberian Peninsula.

Tree hollows are keystone structures that promote forest biodiversity. This study analyses the spatio‐temporal diversity of spiders in these microhabitats. Forty‐eight emergence traps were installed in tree cavities of Quercus pyrenaica forests in the Iberian Peninsula. Traps were collected monthly during a complete year. Generalised linear models and canonical correspondence analysis were used to evaluate the effect of two physical (hollow volume and height above ground) and three biotic variables (beetle richness and abundance and isopod abundance) on the spider diversity and composition of the entire assemblage and of the foraging guilds. Moreover, we examined the temporal segregation of the species using beta diversity metrics. Tree hollows hosted a rich spider assemblage (87 species) including 10 endemic and one vulnerable species. We registered four tree‐bark obligate and one hollow‐dependent species. Hollow height and beetle richness were the variables that better explained richness, while all variables analysed influenced spider abundances. However, contrary to the observed effect for other taxa (i.e. beetles), bigger cavities did not host more spider species. Temporal beta diversity throughout the year was very high and primarily explained by species turnover suggesting a temporal species segregation. We conclude that tree hollows constitute a key habitat for forest spiders and that special attention must be paid to the preservation of this microhabitat in forest ecosystems.