Foraging trail traffic rules: a new study method of trajectories of the harvester ants.

Harvester ants are one of the most extensively studied groups of ants, especially the group foraging ants, Messor barbarus (Linnaeus, 1767), which construct long-lasting trunk trails. Limited laboratory investigations have delved into head-on encounters along foraging trails involving workers moving in opposing directions, with fewer corresponding studies conducted in the natural environment. To address this gap, we devised an in-field experimental design to induce lane segregation on the foraging trunk trail of M. barbarus. Using an image-based tracking method, we analyzed the foraging behavior of this species to assess the costs associated with head-on encounters and to figure out the natural coexistence of outgoing and returning workers on a bidirectional route. Our results consistently reveal heightened straightness and speed in unidirectional test lanes, accompanied by an elevated foraging rate compared to bidirectional lanes. This suggests a potential impact of head-on collisions on foraging behavior, especially on foraging efficiency. Additionally, Kinematic analysis revealed distinct movement patterns between outbound and inbound flows, particularly low speed and sinuous trajectories of inbounding unladen workers. The study of encounter rates in two traffic systems hints at the plausible utilization of individual memory by workers within trails, underscoring the pivotal role of encounters in information exchange and load transfer.

Phylotranscriptomics interrogation uncovers a complex evolutionary history for the planarian genus Dugesia (Platyhelminthes, Tricladida) in the Western Mediterranean.

The Mediterranean is one of the most biodiverse areas of the Paleartic region. Here, basing on large data sets of single copy orthologs obtained from transcriptomic data, we investigated the evolutionary history of the genus Dugesia in the Western Mediterranean area. The results corroborated that the complex paleogeological history of the region was an important driver of diversification for the genus, speciating as microplates and islands were forming. These processes led to the differentiation of three main biogeographic clades: Iberia-Apennines-Alps, Corsica-Sardinia, and Iberia-Africa. The internal relationships of these major clades were analysed with several representative samples per species. The use of large data sets regarding the number of loci and samples, as well as state-of-the-art phylogenomic inference methods allowed us to answer different unresolved questions about the evolution of particular groups, such as the diversification path of D. subtentaculata in the Iberian Peninsula and its colonization of Africa. Additionally, our results support the differentiation of D. benazzii in two lineages which could represent two species. Finally, we analysed here for the first time a comprehensive number of samples from several asexual Iberian populations whose assignment at the species level has been an enigma through the years. The phylogenies obtained with different inference methods showed a branching topology of asexual individuals at the base of sexual clades. We hypothesize that this unexpected topology is related to long-term asexuality. This work represents the first phylotranscriptomic analysis of Tricladida, laying the first stone of the genomic era in phylogenetic studies on this taxonomic group.

Checklist of Moroccan aquatic beetles (Coleoptera: Hydraenidae Mulsant, 1844). New records and updates.

Several field surveys at 391 freshwater localities between 1985 and 2019 were undertaken in Morocco. Altogether, our field studies identified 67 species belonging to three genera (Hydraena, Limnebius, and Ochthebius), and representing 85.89% of the Hydraenidae fauna of the country. The species Hydraena exarata Kiesenwetter, 1866 is reported for the first time from Africa, and Ochthebius (Ochthebius) thermalis Janssens, 1965 and O. (Ochthebius) grandipennis Fairmaire, 1879 are here recorded for the first time from Morocco. These findings increased the number of Moroccan Hydraenidae to 78. Ochthebius semisericeus Saint-Claire Deville, 1914 and O. viridis Peyron, 1858 are excluded from the Moroccan fauna. Furthermore, the checklist presented in this work includes 15 Moroccan endemic, 19 Ibero-Maghrebian endemic and 8 Maghrebian endemic species. A biogeographical analysis shows that the Hydraenidae from Morocco are essentially Mediterranean (89.74%), while the Palaearctic elements (7.70%) and the species with wider distributions (2.56%) are less represented, highlighting the general limited dispersion capability of Hydraenidae compared to other water beetle families. The present study can serve as the basis for future progress in the knowledge of the Moroccan Hydraenidae.

Potamophilus acuminatus (Fabricius, 1792): distribution update in North Africa confirmed by COI barcoding sequencing (Coleoptera, Elmidae).

Potamophilus acuminatus (Fabricius, 1792) is here recorded for the first time from Morocco and the recent distribution in Slovakia is updated. The North African distribution was hitherto based only on two larvae from Tunisia. DNA-barcoding confirmed the identification of specimens from Morocco after comparing ten sequences of P. acuminatus from Germany, France and Slovakia. The COI haplotype of the Moroccan samples was quite divergent (0.033-0.035 uncorrected p-distance) compared with European specimens. These high p-distances suggest the existence of a different intraspecific lineage. A brief morphological diagnosis of adults and larvae is given.

Biodiversity and chorology of aquatic beetles (Coleoptera: Elmidae and Hydraenidae) in Kabylia (central-north Algeria). New records and updates.

This work presents a list of water beetles of the families Hydraenidae and Elmidae occurring in Kabylia (central-north of Algeria) based on an exhaustive review of literature (1872-2016) and on more than 2126 individuals collected during field campaigns (2013-2015). Twenty-five species belonging to nine genera of Hydraenidae and Elmidae are here recorded from a total of 25 sites. Ochthebius (Ochthebius) bifoveolatus Waltl, 1835 is here recorded for the first time from Algeria; Hydraena leprieuri, Limnebius pilicauda, and Limnius intermedius are new records for Kabylia.                A biogeographical analysis shows that the Hydraenidae and Elmidae from Kabylia are essentially Mediterranean (80%) and Palaearctic (20%) elements. Elements with wider distributions are absent.

Evaluating anthropogenic impacts on naturally stressed ecosystems: Revisiting river classifications and biomonitoring metrics along salinity gradients.

Naturally stressed ecosystems hold a unique fraction of biodiversity. However, they have been largely ignored in biomonitoring and conservation programmes, such as the EU Water Framework Directive, while global change pressures are threatening their singular values. Here we present a framework to classify and evaluate the ecological quality of naturally stressed rivers along a water salinity gradient. We gathered datasets, including aquatic macroinvertebrate assemblages and environmental information, for 243 river locations across the western Mediterranean to: a) gauge the role of natural stressors (salinity) in driving aquatic community richness and composition; b) make river classifications by encompassing the wide range of environmental and biological variation exhibited by Mediterranean rivers; c) provide effective biomonitoring metrics of ecological quality for saline rivers. Our results showed that water salinity played a pivotal role in explaining the community richness and compositional changes in rivers, even when considering other key and commonly used descriptors, such as elevation, climate or lithology. Both environmental and biologically-based classifications included seven river types: three types of freshwater perennial rivers, one freshwater intermittent river type and three new saline river types. These new saline types were not included in previous classifications. Their validation by independent datasets showed that the saline and freshwater river types represented differentiable macroinvertebrate assemblages at family and species levels. Biomonitoring metrics based on the abundance of indicator taxa of each saline river type provided a much better assessment of the ecological quality of saline rivers than other widely used biological metrics and indices. Here we demonstrate that considering natural stressors, such as water salinity, is essential to design effective and accurate biomonitoring programmes for rivers and to preserve their unique biodiversity.