Body colouration is involved in multiple aspects of species ecology and behaviour. Melanism, a common colour polymorphism, has been associated with camouflage and thermoregulation, particularly in diverse, high-altitude habitats of arid regions. This study reports the first case of melanism in the lacertid Acanthodactylus boskianus, two scorpions, Leiurus haenggii and Compsobuthus manzonii, and the first records of brown-black melanistic colouration in three rodent species, Acomys dimidiatus, Meriones crassus, and Sekeetamys calurus, in the dark lava fields (harrat) of north-western Saudi Arabia. Additionally, it expands observations of melanism in the endemic colubrid Rhynchocalamus hejazicus and provides the first documented records of brown-black melanistic Acomys russatus for the region, consistent with earlier predictions. These observations suggest that colour polymorphism may serve a cryptic function through background matching in both diurnal and nocturnal species, but other roles of melanism should be further investigated. Despite their extent, lava fields in arid regions remain poorly studied due to their remoteness and limited accessibility, yet they offer unique opportunities to investigate phenotypic evolution in arid ecosystems.

Deserts harbor unique natural and cultural heritage that is found nowhere else in the world. However, threats to these heritage resources are rising due to increasing levels of accessibility, human population and exploitation of natural resources. Thus, new alternative tools are needed to safeguard these fragile environments. In this respect, ecotourism has the potential to preserve the desert biome while supporting local cultures, traditional livelihoods and sustainable development. Deserts display many opportunities to promote ecotourism, such as unique biodiversity protected by large national parks and reserves, geological features, archeological and historical sites evidencing past cultures, and a great variety of ethnic groups and costumes. Still, protection of desert heritage is challenged in many countries due to low levels of security, development and political stability. Ecotourism generates a plethora of environmental, economic and socialcultural impacts that need to be considered when developing tourist activities in desert environments. However, ecotourism should not be envisaged as a panacea for all the challenging impacts that deserts are facing, but it can offer a sustainable tool to contribute positively to the wellbeing of people and communities living within deserts. Ultimately, desert ecotourism can contribute to the 2030 agenda of the United Nations for the Sustainable Development Goals and the conservation and management of desert heritage.

Aquila verreauxii es considerada un depredador altamente especializado que se alimenta principalmente de damanes y ocupa hábitats montañosos escarpados a lo largo de su distribución en África y la Península Arábiga. A pesar de su gran tamaño y de sus similitudes morfológicas con rapaces carroñeras, el consumo de carroña ha sido raramente documentado y no se había registrado previamente en la Península Arábiga. En este estudio reportamos el primer caso confirmado de uso sostenido de carroña por Aquila verreauxii en Arabia Saudita, documentado mediante cámaras activadas por movimiento en una estación de cebo en la Reserva de la Biosfera Harrat Uwayrid, en la región de AlUla, al noroeste de Arabia Saudita. Dos individuos de Aquila verreauxii visitaron un cadáver de cabra en la estación de cebo durante cuatro días consecutivos en diciembre de 2024, con una presencia combinada que superó las 11 horas. Las águilas mostraron alimentación repetida y prolongada, sin aparente reticencia en la explotación de la carroña ni competencia interespecífica. No se registraron buitres ni otras grandes rapaces en el sitio durante el período de cuatro días. Nuestras observaciones sugieren que la carroña puede representar una oportunidad de alimentación de bajo costo para Aquila verreauxii en este entorno árido, donde las presas tradicionales pueden ser menos abundantes. Nuestras observaciones también aportan evidencia adicional de flexibilidad conductual en una rapaz típicamente considerada un depredador obligado. Este estudio resalta el valor del seguimiento sistemático para detectar comportamientos poco frecuentes y mejorar el conocimiento de la ecología trófica de las rapaces en regiones poco estudiadas. [Traducción de Bruno Herlander Martins]

The common perception of the Desert biome is that it generally constitutes remote areas of low diversity. However, the world's largest warm desert, the Sahara, together with the neighboring arid Sahel exhibit high topographic and climate heterogeneity and have experienced strong climatic oscillations that have shaped land-cover and biodiversity distribution. This review summarizes the knowledge on the Sahara-Sahel biodiversity patterns based on the distribution of terrestrial vertebrate species richness (also called α-diversity) and species turnover or the change in species among sites (β-diversity). The distribution of α-diversity in the Sahara-Sahel follows the general latitudinal gradient, with higher percentage of species found in the southern Sahel region. This broad latitudinal gradient pattern is disrupted by higher number of species distributed along hypothesized ecological corridors and refugia. The distribution of β-diversity highlights the boundaries of the Sahara-Sahel hotspots of species richness. At local scale, recent studies have emphasized the natural value of isolated and residual wetlands (oases, lakes, and seasonal rivers) of high productivity, acting as refugia for relict populations. Among these wetlands, mountain rock-pools constitute local hotspots of biodiversity.

This work provides the first confirmed evidence of successful inland breeding of the Sooty Falcon (Falco concolor) in the AlUla region of northwestern Saudi Arabia, significantly expanding the known breeding range and population size of this globally threatened ("Vulnerable") species. Surveys conducted across six nature reserves and six areas rich in biodiversity between 2023 and 2024 documented at least 38 breeding pairs, primarily concentrated in the Sharaan National Park, with additional pairs observed in Gharameel Nature Reserve and Wadi Nakhlah Nature Reserve. Breeding behaviours, including courtship, copulation, territorial nest defence, hunting, and the successful fledging of juveniles, were predominantly observed either on top of small inselbergs or on steep sandstone cliffs and rocky escarpments, highlighting the suitability of these habitats, which are widespread throughout the AlUla region. This newly identified population represents nearly 2% of the estimated global breeding population of the species, underscoring the conservation significance of this discovery. The findings demonstrate the ecological adaptability of the Sooty Falcon to arid inland environments and emphasize the critical role of conservation areas, such as those established by the Royal Commission for AlUla, in safeguarding and enhancing core habitats and protecting populations of threatened raptors. Further research and long-term monitoring are essential to refine population estimates, understand species ecology, habitat suitability, and inform adaptive conservation strategies.

Large-scale monitoring networks employing remote sensors have harnessed big data to evaluate conservation efforts on a global scale. While dryland ecosystems are anticipated to expand, and management activities like rewilding and habitat restoration are increasing, the use of data streams and modern analytical methods to plan conservation interventions and quantify their effectiveness remains limited. We recommend establishing a global network for dryland practitioners to bridge critical data gaps, providing two real-world examples. A pilot study in the Kingdom of Saudi Arabia shows how coordinated use of multiple remote sensors and a standardised data pipeline could improve interoperability and facilitate the use of more accurate ecological models. Likewise, the Wildlife Observatory of Australia demonstrates that robust metadata and shared analytical frameworks enable the effective integration of diverse datasets using hierarchical occupancy models. Key steps to build this network include forming a steering committee, engaging stakeholders from various backgrounds, piloting projects in different regions, agreeing on protocols and exploring seed funding opportunities.

The desert biome is usually perceived as bare and rather homogeneous area that exhibit relatively low diversity in comparison to other biomes. However, deserts are surprisingly rich, harboring about 25% of continental vertebrate species and comprising highly adapted and specialized species that are found nowhere else. They display high rates of endemism due to the adaptive processes of organisms to the extreme environmental conditions, as well as locally endangered hotspots of biodiversity. Biodiversity is distributed according to the extreme climatic conditions of deserts, and concentrates in mountains, suitable climatic corridors, and in the rare, generally small, and fragile wetlands. Geological events and palaeoclimatic oscillations largely drove the main evolutionary processes, acting over diversification and speciation events mainly through vicariance. Remarkable and unique adaptations for survival in the aridity, heat, and salinity conditions of deserts are found in species inhabiting these environments. Desert biodiversity is currently threatened by increasing human exploitation activities and climate change. Still, deserts classify as one of the last wild biomes on Earth, where implementing conservation actions would be most cost-effective. Long-term conservation of desert biodiversity requires appropriate policy instruments that promote conservation and sustainable use of natural resources. Raising environmental alertness and pride within local communities of the value and uniqueness of the desert wildlife is needed to pressure strong policy change.

Understanding intraspecific venom variation requires distinguishing the contributions of neutral population history from natural selection. This study aims to determine whether venom variation in Vipera ammodytes species complex is structured across eight phylogenetic groups. Despite a complex evolutionary history, venom composition did not differ among phylogenetic groups within the analytical framework used, suggesting that shared ancestry alone does not explain venom variation. Whether local adaptation to environmental conditions explains the observed variation remains an open question for future studies.

Land-use/land-cover (LULC) is a critical driver of ecosystem dynamics globally. Arid regions are particularly vulnerable to global change factors, and comprehensive LULC assessments are crucial for evaluating the environmental stability of these areas. Despite considerable developments of remote sensing (RS) data/products and classification algorithms, the available multi-scale maps fail to represent the complex heterogeneity of LULC in these areas. The major limitation resides not on the improvements in data resolutions or the complexity of algorithmic decisions, but rather on the lack of approaches prioritizing detailed categorization of LULC in arid regions. Therefore, we propose an integrative multi-classification approach of LULC based on RS techniques and in-situ data for general application in arid regions, using the north-western Saudi Arabia as pilot area. Using in-situ data (N = 7523) and a Landsat-8 time-series, we applied a supervised classification of non-dynamic classes representing regional geodiversity, combined with a clustering analysis of dynamic harmonic regression model coefficients to categorize ecologically dynamic classes. The map was obtained with high accuracy for non-dynamic classes (Kappa≈0.84; overall accuracy≈0.87; overall producer's accuracy≈0.86; overall user's accuracy≈0.89) and dynamic classes (combined overall accuracy≈0.76). The final map presents a total of 15 classes, considerably improving the available categorical resolution for the study area. The approach is transferable to other arid regions, having the potential to integrate other finer-scale RS data and classification algorithms. We urge for increased efforts in data collection and the implementation of approaches considering the prominent diversity of LULC in arid regions.

Background:This study presents the first faunistic records of blister beetles (Coleoptera, Meloidae) from north-western Saudi Arabia, specifically Hejaz mountains and north Tihama, expanding the known distribution range of the species within the country. Field surveys were conducted between 2022 and 2024, aiming to cover different seasons. These observations contribute to the knowledge of the diversity of meloid fauna of the country and underscoring the importance of continued faunistic exploration in north-western Saudi Arabia, a region that remains relatively under-surveyed in terms of meloid diversity. New information:Three species (Hycleus borchmannianus, Hycleus trizonatus, Mylabris filicornis) and one genus (Sitaris) are recorded for the first time in Saudi Arabia. Besides that, this work also provides the first description of the male morphology and genitalia of Mylabris desertica Bologna, 2007.

Background/Objectives: Ants are one of the most abundant animal groups on the planet and have a considerable impact on ecosystems. In the Cabo Verde Archipelago, the study of invertebrates is very scarce and ants are no exception. Methods: In this work we focus on the taxonomic analysis of formicids and study their distribution and the possible presence of invasive species in the Cabo Verde Islands. In addition, the diversity of Cabo Verde ants is compared with that of the closest African coastal countries, Senegal and Mauritania, to study a possible colonization of African ants into the archipelago. For this, we use two molecular markers, cytochrome oxidase I and the wingless gene, to perform phylogenetic analyses and haplotype networks that facilitate identification. Results: Nine taxa were identified, five invasive species, Paratrechina longicornis, Pheidole megacephala, Trichomyrmex destructor, Brachyponera sennaarensis, and Solenopsis globularia, one endemic Monomorium subopacum and three unidentified species of native genera, Monomorium sp., Lepisiota sp. Camponotus sp. Conclusions: Molecular network patterns as well as phylogenetic analyses suggest that ants are widespread throughout the archipelago, a likely consequence of human introductions.

Challenges in freshwater organism conservation in West Africa are worsened by significant knowledge gaps, even for charismatic species like crocodiles. This study addresses these gaps by assessing crocodile diversity, distribution, and conservation threats in Guinea-Bissau, where existing data is outdated. We used visual surveys, inquiries, molecular barcoding, camera trapping, and bibliographic reviews to investigate crocodile populations. Notably, we found evidence suggesting the Nile crocodile (Crocodylus niloticus), previously thought extinct in West Africa since about 200 years, may persist in Guinea-Bissau's Cacheu region. We also confirmed the presence of the West African crocodile (Crocodylus suchus) in major river basins and coastal lagoons, including the Bijagós Archipelago, and the West African dwarf crocodile (Osteolaemus cf. tetraspis) in the southern mainland and the Bijagós Archipelago. Habitat loss and deliberate killings were identified as major threats. Standardized surveys and genetic sampling are essential to assess population size, connectivity, and genetic diversity, informing evolutionary studies and conservation planning. Conservation efforts should prioritize habitat protection through community-managed reserves and restoration initiatives. Additionally, engaging local communities to raise awareness and develop conflict mitigation strategies is crucial, particularly in areas with human-crocodile interactions.

Aim: Macroscale biodiversity inferences are critical for spatial conservation planning, yet they are affected by the limitations of global datasets and the paucity of genetic data. In this study, we conducted a comprehensive sampling campaign and explored how biodiversity shortfalls impact spatial diversity metrics across a mid-altitude desert ecotone, where mega conservation and restoration projects are underway. Location: AlUla region (NW Arabian Peninsula). Taxa: Terrestrial reptiles. Methods We generated a DNA barcode library including 580 field-collected samples to investigate species distributions, candidate species and intraspecific diversity. Species distributions were mapped using climatic envelopes, while candidate species and intraspecific diversity were assessed with phylogenetic methods. Patterns of alpha and beta diversity were mapped based on IUCN and GARD expert maps (expected diversity) and on an integrative assessment combining field and bibliographic occurrences (observed diversity). Topographic drivers of nucleotide diversity were tested using Generalised Linear Mixed Models. Results: Over one-third of the verified species in the region (n = 58) experienced Linnean, Wallacean or Darwinian shortfalls, including 6 candidate species, 11 new to the region and 7 harbouring significant intraspecific diversity. Additionally, 13 species predicted by expert maps were absent. Both IUCN and GARD projections showed significant mismatches with observed alpha and beta diversity, though GARD provided alpha-diversity estimates closer to observed patterns. Nucleotide diversity increased with absolute altitude. Main Conclusions: Field and genetic-based data significantly enhance biodiversity knowledge and conservation tools for this rapidly developing desert region. By addressing the critical limitations of macroscale approaches in undersampled yet diverse landscapes, we demonstrate how global databases often overlook local community turnovers, misleading diversity estimates. Thereby, we highlight the need for fine-scale integrative research to inform conservation strategies and the power of DNA barcoding for inter- and intraspecific biodiversity assessments.

During recent botanical expeditions in the northwestern Saudi Arabia, Sarga purpureosericea Spangler was recorded and collected for the first time in the country. This finding enriches Saudi Arabia’s grass flora and highlights the importance of further botanical exploration. We formally include this species in the national flora, supported by a voucher specimen deposited at the University of Porto Herbarium (PO). This record bridges a significant biogeographical gap between eastern Africa and the Indian subcontinent. Additionally, we provide a second-step lectotypification of the name. The original lectotypification, based on specimens housed at the Kew Herbarium (K) and the Missouri Botanical Garden Herbarium (MO), constitutes a first-step designation under Article 9.17 of the ICN. We now designate a second-step lectotype that aligns more precisely with Spangler’s original intent.

ABSTRACTLinnaean and Wallacean shortfalls (Uncertainties on species taxonomy and distribution, respectively) are major factors hampering efficient conservation planning in the current context of biodiversity erosion. These shortfalls concern even widespread and abundant species in relatively well-studied regions such as the Mediterranean biodiversity hotspot which still hosts a large fraction of unrecognised biodiversity, notably in small vertebrates. Species delimitations have long been based on phylogenetic analyses of a small number of standard markers, but accurate lineage identification in this context can be obscured by incomplete lineage sorting, introgression or isolation by distance. Recently, integrative approaches coupling various sets of characters or analyses of contact zones aiming at estimating reproductive isolation (RI) have been advocated instead. Analyses of introgression patterns in contact zone with genomic data represent a powerful way to confirm the existence of independent lineages and estimate the strength of their RI at the same time. The Spiny-footed Lizard Acanthodactylus erythrurus (Schinz, 1833) is widespread in the Iberian Peninsula and the Maghreb and exhibits a large amount of genetic diversity, although the precise number and distribution of its genetic lineages remain poorly understood. We applied a RADseq approach to obtain a genome wide SNPs dataset on a contact zone in central Morocco between the previously described Rif and Middle-Atlas lineages. We show that these two lineages exhibit strong RI across this contact zone, as shown by the limited amount and restricted spatial extant of gene flow. We interpret these results as evidence for species-level divergence of these two lineages. Our study confirms the usefulness of RADseq approaches applied on contact zones for cryptic diversity studies and therefore to resolve Linnaean and Wallacean shortfalls.

The desert vipers of the genus Cerastes are a small clade of medically important venomous snakes within the family Viperidae. According to published morphological and molecular studies, the group is comprised by four species: two morphologically similar and phylogenetically sister taxa, the African horned viper ( Cerastes cerastes ) and the Arabian horned viper ( Cerastes gasperettii ); a more distantly related species, the Saharan sand viper ( Cerastes vipera ), and the enigmatic Böhme’s sand viper ( Cerastes boehmei ), only known from a single specimen in captivity allegedly captured in Central Tunisia. In this study, we analyzed one mitochondrial marker (COI) as well as genome-wide data (ddRAD sequencing) from 28 and 41 samples, respectively, covering the entire distribution range of the genus to explore the population genomics, phylogenomic relationships and introgression patterns within the genus Cerastes . Additionally, and to provide insights into the mode of diversification of the group, we carried out niche overlap analyses considering climatic and habitat variables. Both nuclear phylogenomic reconstructions and population structure analyses have unveiled an unexpected evolutionary history for the genus Cerastes , which sharply contradicts the morphological similarities and previously published mitochondrial approaches. Cerastes cerastes and C. vipera are recovered as sister taxa whilst C. gasperettii is a sister taxon to the clade formed by these two species. We found a relatively high niche overlap (OI > 0.7) in both climatic and habitat variables between C. cerastes and C. vipera , contradicting a potential scenario of sympatric speciation. These results are in line with the introgression found between the northwestern African populations of C. cerastes and C. vipera . Finally, our genomic data confirms the existence of a lineage of C. cerastes in Arabia. All these results highlight the importance of genome-wide data over few genetic markers to study the evolutionary history of species.

Hyperarid habitats comprise the most dominant and harsh portion of the Sahara Desert, yet how local biotas have responded to paleoclimatic shifts and landscape heterogeneity remains unclear. Here, we assess the historical biogeography of Cerastes cerastes , a conspicuous but poorly known vertebrate inhabiting the hyperarid Sahara, to understand the links between intermittent and stable climatic suitability and patterns of genetic diversity and differentiation in these extreme environments. We combine phylogeographic and ecological modelling tools using a comprehensive species dataset, which includes DNA samples (n = 62) and occurrence records (n = 557) covering most of its range. We show that paleoclimatic oscillations were major evolutionary and biogeographic drivers in C. cerastes , which exhibits different levels of intra-specific diversity and allopatric lineage structuration across the desert. High lineage richness in the north-western Sahara contrasts with an overall lack of genetic diversity throughout the central and eastern Sahara. Climatic refugia along the desert 's periphery and around mountain patches harbour single endemic lineages, stressing the links between stable climatic conditions and population isolation and divergence. Increasing climatic suitability during historical arid phases prompted widespread connectivity across the desert. This study lays the groundwork for better understanding the historical dynamics of the hyperarid Sahara.