The present checklist of the spiders (Araneae) of Algeria is based on literature items published from 1846 to 2022. Altogether 876 species belonging to 51 families are listed. Taxonomic references are mentioned for each species, with indication of synonymous usage or taxa changes. Information about species distribution in the Algerian provinces is also provided, revealing significant disparities in knowledge about each province. Linyphiids present the highest number of known species (155) and the highest endemic richness (54 species). Eight families are represented by a single species. 227 species are known exclusively from Algeria. Moreover, a comparison was executed between the results reported in Algeria and those reported in the neighboring countries (Tunisia, Morocco, and Libya).

The application of geometric morphometry on mosquito wings (Culicidae) is considered a powerful tool for evaluating correlations between the phenotype (e.g., shape) and environmental or genetic variables. However, this has not been used to study the wings of the avian malaria vector, Culiseta longiareolata. Therefore, the goal of this study is to investigate the intra-specific wing variations between male and female Cs. longiareolata populations in different types of larval habitats and climatic conditions in Algeria. A total of 256 Cs. longiareolata mosquito samples were collected from January 2020 to July 2021 in three cities (Annaba, El-Tarf, and Guelma) of northeastern Algeria that have two distinct climatic condition levels (sub-humid and sub-arid) and different types of larval habitats (artificial and natural). Nineteen (19) wing landmarks (LMs) were digitized and analyzed based on geometric morphometry. Our results revealed differences in the wing shape of female and male mosquito populations, indicating sexual dimorphism. Moreover, canonical variance analysis (CVA) showed that factors, such as climatic conditions and type of larval habitats, also affect the wing shape of female and male Cs. longiareolata mosquito populations. Furthermore, the wing shape of male populations was more distinct compared with female populations.

Spiders, as predatory arthropods, play essential roles in ecosystem equilibrium and serve as bioindicators. To contribute to the understanding of spider diversity in northeast Algeria (Annaba province), a survey of spider fauna was conducted in both forest and urban sites over two consecutive years using the "hand collecting" method. A total of 879 adult spiders (681 females and 198 males) were identified, representing 25 families and 67 species. The Salticid Plexippus paykulli (Audouin, 1826) was the most abundant species, with 127 specimens collected. The most abundant families were Salticidae and Araneidae, with counts of 171 and 139 individuals, respectively. The Shannon-Weaver index varied from 2.17 to 3.68 bits across the different sites, while evenness values ranged from 0.60 to 0.75. This study significantly expanded the known spider species in Annaba province from 96 to 138.

The rediscovery of Pseudomyrmecion ramalium Bedel, 1885, a rare and endemic saproxylic longhorn beetle, in the Djebel Edough forest in Algeria is reported. Hind wings are for the first time showed and described, evidencing the brachyptery of this species. Erroneous nomenclatorial, biological and chorological data referred by previous authors are discussed and corrected. This species, which had not been observed in the region since 1900, is an obligate saproxylic insect exclusively associated with the Algerian oak Quercus canariensis Willd. Classified as an endangered species on the IUCN Red List due to its rarity and the threats to its habitat, P. ramalium represents a conservation priority. Its rediscovery highlights the need for further research to assess the current state of its population and better understand its ecological requirements. This information will be crucial for developing effective conservation strategies and preserving its fragile habitat.

Trachymela sloanei (Blackburn, 1897) (Coleoptera: Chrysomelidae: Chrysomelinae), a leaf beetle native to Australia and recognized as a defoliator of Eucalyptus spp. (Myrtaceae), is reported for the first time from Algeria and the African continent. In May 2025, 20 adults were collected from Eucalyptus camaldulensis in the urban area of Sidi Amar (Annaba, northeastern Algeria), where characteristic foliar damage and feeding traces were observed. Identification was confirmed using diagnostic morphological characters. Field evidence indicates a reproducing population actively feeding on ornamental Eucalyptus trees. Considering its invasive history elsewhere, this detection highlights the risk of further spread and potential impacts on Eucalyptus plantations and urban greenery in North Africa. The present record expands the known distribution of T. sloanei and underscores the need for continued surveillance of Eucalyptus-associated pests in the Mediterranean region.