Recent research in various Moroccan areas allowed an update and a revision of the Moroccan Ephemeroptera checklist. In this case, 54 species are now listed, belonging to 10 families and 26 genera. The distribution of all studied species is discussed, as well as their biogeographical affinities. Moroccan Mayflies are characterized by a clear dominance of Mediterranean elements with a strong rate of endemism (33.4%).

Baetis rifensissp. nov. is the first representative of the Baetis fuscatus group to be described from the Maghreb. It was collected from streams in the Rif region of northern Morocco. All species of the B. fuscatus group are morphologically very similar, with slight differences in colour. Thus, in addition to morphological description, species delimitation based on genetic evidence was carried out. The new species was compared with other members of the B. fuscatus group from the Palaearctic region.

Based on recently collected larvae from Algeria and Morocco, the species delimitation within the genusCentroptilumEaton, 1869 in that region is validated. Two new species are described and illustrated, one from north-eastern Algeria, and one from North Morocco, using an integrated approach with morphological and molecular evidence. A table summarising the morphological differences between the new species andCentroptilum luteolum(Müller, 1776) from Central Europe is provided. Further, molecular evidence for additional undescribed species ofCentroptilumin other regions of the West Palearctic is provided and discussed.

Among mayflies, Baetidae are often considered as easy to recognise at the family level, but difficult to identify at lower level. In several faunistic or ecological studies, the identification remains at the family level; Baetidae are generally considered as widespread and ubiquitous, therefore as poorly informative for ecological studies or bioassessments. Here, a straightforward identification key is offered to larvae of the ten genera of Baetidae reported from Maghreb based on easily observable and understandable characters. The diversity, ecology, and distribution of each taxonomic unit (genera or subgenera) are discussed and the main difficulties for deeper identification are pointed out. Future challenges and remaining taxonomic riddles for Maghrebian Baetidae are detailed.

A new species belonging to the genus Habrophlebia Eaton, 1881 is described at the nymphal stage from the Rif Mountains of Morocco. This species presents unique features, such as the chorionic arrangement of the egg and the ornamentation of the posterior margin of abdominal tergites. It is compared to all west European Habrophlebia species and a table with discriminating characters is given. A phylogenetic reconstruction based on COI sequences fully supports the hypothesis of a new species in the Rif Mountains, with possible further distribution in southern Spain.

The involvement of trait-based approaches is crucial for understanding spatial patterns, energy flow and matter transfer in running water systems, which requires consistent knowledge of the functional structures of aquatic communities, with the advantage of combining physical properties and behavioral mechanisms of food acquisition rather than the taxonomic group. The present study indicated how functional feeding groups may be used as a proxy for classical taxonomic evaluation, as well as the potential interest in incorporating them as indicators of anthropogenic stressors. The composition and abundance of the functional feeding groups of aquatic insects were examined from September 2021 to August 2022 along the Western Rif Region. Benthic samples were collected from nine sampling points in the studied area using a Surber sampler with a mesh size of 500 µm and a diameter of 20*20 cm. The stations included in this work were chosen for their accessibility as well as their position on the hydrographic systems. The abundance of sampled aquatic organisms in the whole study area revealed 5,342 individuals belonging to 60 families and seven orders of aquatic insects, classified into five feeding functional groups. In terms of abundance, Collector-gatherers (Ephemeroptera and Diptera) were the most abundant trophic group at most of the sites, with a proportion of 38.47%. Predators (Coleoptera, Hemiptera and Odonata) were the second group at all sites, followed by Collector-filters, accounting for 39.53%, 28.14% and 22.37% respectively, while Scarpers and Shredders had the lowest representation across all sites with 4.16%. The high number of registered Collectors could be related to their ability to feed on a diverse range of food items compared to the remaining trophic guilds. According to the Canonical Correspondence Analysis results, physicochemical (i.e. T, pH, BOD₅, Cl- and NO₃-) and hydromorphological (i.e. current velocity and depth) variables were amongst the key predictors of shaping the functional structure of aquatic biota during this investigation. It is highly recommended to carry out suitable measures to largely attenuate anthropogenic pressures in order to preserve the integrity of freshwater bodies and their biota.