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.

Ants (Hymenoptera: Formicidae) are integral components of terrestrial ecosystems, contributing to biological regulation, pollination, and soil bioturbation. Their diversity serves as a valuable indicator of ecosystem functioning. This study examines ant assemblages in northeastern Algeria, focusing on the Edough Massif (Annaba Province). Fieldwork was conducted from 2022 to 2024 using two complementary sampling techniques: manual collection and Barber traps, which were collected twice weekly. The study was conducted from March to July at two ecologically contrasting sites, Seraidi and Treat. 3183 individuals representing 15 species were recorded at Seraidi, while 3,356 individuals belonging to 11 species were documented at Treat. All taxa fell within three subfamilies (Myrmicinae, Formicinae, and Dorylinae), with Myrmicinae dominating both sites. Diversity indices revealed greater richness and overall diversity at Seraidi (H’ = 2.54; E = 0.94), whereas Treat, although less affluent, exhibited slightly higher evenness (H’ = 2.29; E = 0.96). These findings underscore the ecological significance of Edough’s ant communities and highlight the influence of habitat heterogeneity on species composition and community structure.