The study of Plecoptera in north-western and north-central Algeria enabled the identification of 14 collected species already known from the country. Comparative analysis with previously published data from the north-western Algeria revealed four species in common, the absence of two previously reported species, new records of two species for the region (Tyrrhenoleuctra tangerina (Navás, 1922) and Brachyptera algirica Aubert, 1956), a complete absence of Plecoptera in Tafna wadi, and a reduction in the known distribution range of Eoperla ochracea (Kolbe, 1885). In the Jijel region, 11 species were recorded, with an extension of their known distribution, particularly for Amphinemura berthelemyi In Yasri et al. (2013), Protonemura drahamensis Vinçon & Pardo, 2006, and Leuctra khroumiriensis Vinçon and Pardo, 1998. The endemic species Marthamea bayae Vinçon, Lamine, Lounaci & Reding, 2019 (in Lamine et al. 2019) is reported here for the first time since its original description. A molecular phylogenetic analysis using the standard animal barcode gene clarified the status of Perla larvae as P. marginata (Panzer, 1799), indicating a closer affinity with species previously identified as P. marginata and a distant relationship with P. pallida Guérin‑Méneville, 1838.

Microplastic pollution is an issue arising in freshwater ecosystems worldwide, yet data from North Africa remains scarce. In this study, aquatic insects were collected from 17 freshwater sites distributed across three bioclimatic regions in Algeria between 2024 and 2025. A total of 25 species belonging to 12 families and 5 orders were analyzed to assess the occurrence and polymer composition of microplastics (MPs). MPs were detected in 72% of the analyzed specimens, with a total of 105 particles identified. Particle sizes ranged from 5.8 to 124 µm, with fibers representing the dominant morphological shape. FTIR analysis recognized polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) as the predominant polymers, suggesting multiple anthropogenic contamination sources. Generalized linear model (GLM) analyses revealed significant associations between MP occurrence and functional feeding groups, particularly collector-filterers (p < 0.001) and members of the family Hydropsychidae (p < 0.01). These findings provide the first baseline data on microplastic contamination in freshwater macroinvertebrates from Algeria and highlight the potential usefulness of aquatic insects for monitoring freshwater MP contamination.

Untreated urban wastewater is a major driver of aquatic ecosystem degradation, yet its impacts on saline wetlands, notably Sabkha ecosystems, remain poorly understood. We investigated the fine-scale responses of benthic macroinvertebrates to wastewater discharge in Sabkhat El Mahmal, a Mediterranean Sabkha in northeastern Algeria. During monthly surveys over a one-year period, we concurrently measured physicochemical and bacteriological water parameters and sampled benthic macroinvertebrates at six stations along a pollution gradient, followed by community analyses using multivariate and indicator-species approaches. Urban wastewater inputs induced localised desalination, elevated phosphate concentrations, and increased faecal coliform counts, leading to significantly degraded water quality near the discharge outlet. While taxonomic richness, abundance, and diversity did not vary significantly among stations, community structure shifted markedly. Polluted stations were dominated by pollution-tolerant taxa such as Chironomidae (Diptera) and Corixa (Hemiptera, Corixidae), whereas less impacted stations were characterised by Cordulegaster (Odonata, Cordulegastridae). These results demonstrate that urban wastewater alters community structure through biotic homogenisation and the replacement of sensitive taxa with tolerant ones, without necessarily reducing coarse diversity metrics. Our findings provide empirical evidence of wastewater impacts in Mediterranean Sabkhas and underscore the urgent need for improved wastewater management to safeguard these ecologically valuable saline wetlands.

A new species, Baetis (Baetis) dihyaesp. nov., belonging to the Baetis alpinus species group, is described and illustrated based on larval material collected in the Aurès Mountains (northeastern Algeria) in 2020–2021. This new species is closely related to three European species, e.g., Baetis (B.) alpinus (Pictet, 1843); B. (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 by the combination of the following characteristics: (i) more than one short, stout bristle at the tip of segment II of the maxillary palp and (ii) a well-developed paracercus. However, the new species clearly differs from all congeners of the Baetis alpinus species group primarily by the (a) structure of mouthparts—with 14–18 long submarginal setae arranged in a single irregular row on the dorsal surface of the labrum; 2–6 short, stout bristles at the tip of segment II of the maxillary palp; and segment II of the labial palp without a considerably developed apico-internal lobe); (b) setation of abdominal terga, with a few triangular-shaped scales sparsely scattered near the posterior margin only; and (c) a well-developed paracercus, comprised of more than 50 segments. Primary data on the biology and distribution of this new species are provided, and molecular affinities are verified by the analysis of COI (barcode) sequences. Detailed notes on the distribution of mayfly species belonging to the Baetis alpinus species group common in Western Europe and the western part of North Africa are presented. The historical movement of Baetis representatives between Europe, North West Africa, and subsequently Algeria, with the land bridges ‘Strait of Gibraltar’ and ‘Strait of Sicily’ as colonization routes, is discussed in detail and identified in the present study as the Western Algeria colonization path and Eastern Algeria colonization path, respectively.

Keywords: Baetinae; mayflies; taxonomy; Baetis (Baetis) dihyae sp. nov.; new characters; COI; distribution; North Africa

Ecdyonurus aurasius sp. nov. , a micro-endemic species reported from several streams within the Aurès Mountains (north-eastern Algeria), is described and illustrated at nymphal, subimaginal and imaginal stages of both sexes. Critical morphological diagnostic characters distinguishing the new species are presented, together with molecular affinities as well as notes on the biology and distribution of the species.

Besides their important ecological role in flowing waters, blackflies (Diptera: Simuliidae) may pose medical and veterinary risks. For seventeen months, we surveyed the blackflies of ten localities across the Aures Mountains, in the Saharan Atlas, Algeria, and recorded eight taxa (i.e. species, species groups or species complexes). High altitude sites were dominated by the Simulium ornatum (Meigen, 1818) group, whereas sites located on the southern slope of the Aures Mountains were occupied by the eurytopic Simulium velutinum (Santos Abreu, 1922) complex and the thermophilic, pollutant-tolerant Simulium ruficorne Macquart, 1838 ‘A’ morphotype.Co-inertia analysis was used to determine the relationship between a species’ abundance and habitat types. The co-inertia analysis revealed a likely co-structure between blackfly assemblages and measured environmental descriptors (water temperature, conductivity, current velocity, bed width, etc.) in sampled habitats. This confirmed the importance of altitude as a driver of blackfly distribution. Our results also showed that there has been an increase in anthropogenic pressures on the vulnerable freshwater biota of the Aures Mountains.

The hitherto unknown larva of Limnephilus barbagaensis Malicky, Sekhi & Lounaci 2019, micro-endemic of the Aures Mountains (Mounts des Aures, Algeria), is described. The diagnostic features of the species are listed, illustrated, compared with those of similar species, and some information on the ecology is included. In addition, the first record of Hydropsyche siltalai Döhler 1963 in the Aures Region and Northeast Algeria is also reported.

The caddisfly fauna of Algeria is poorly known and the few sporadic studies available were carried out decades ago. In this study, caddisfly larvae, pupae, and adults were collected in 11 stream localities from the Aures region, northeastern Algeria. Caddisflies were regularly sampled between April 2018 and February 2020. Two genera are new records to Algeria: Plectrocnemia and Setodes. In addition, four Trichoptera species are new to the Algerian fauna: Tinodes dives, Hydropsyche modesta, Plectrocnemia conspersa and Setodes acutus. Future caddisfly surveys in the region will doubtlessly contribute significantly to the incompletely known Trichoptera fauna of Algeria.