Aquatic larvae of many Rhithrogena mayflies (Ephemeroptera) inhabit sensitive Alpine environments. A number of species are on the IUCN Red List and many recognized species have restricted distributions and are of conservation interest. Despite their ecological and conservation importance, ambiguous morphological differences among closely related species suggest that the current taxonomy may not accurately reflect the evolutionary diversity of the group. Here we examined the species status of nearly 50% of European Rhithrogena diversity using a widespread sampling scheme of Alpine species that included 22 type localities, general mixed Yule-coalescent (GMYC) model analysis of one standard mtDNA marker and one newly developed nDNA marker, and morphological identification where possible. Using sequences from 533 individuals from 144 sampling localities, we observed significant clustering of the mitochondrial (cox1) marker into 31 GMYC species. Twenty-one of these could be identified based on the presence of topotypes (expertly identified specimens from the species' type locality) or unambiguous morphology. These results strongly suggest the presence of both cryptic diversity and taxonomic oversplitting in Rhithrogena. Significant clustering was not detected with protein-coding nuclear PEPCK, although nine GMYC species were congruent with well supported terminal clusters of nDNA. Lack of greater congruence in the two data sets may be the result of incomplete sorting of ancestral polymorphism. Bayesian phylogenetic analyses of both gene regions recovered four of the six recognized Rhithrogena species groups in our samples as monophyletic. Future development of more nuclear markers would facilitate multi-locus analysis of unresolved, closely related species pairs. The DNA taxonomy developed here lays the groundwork for a future revision of the important but cryptic Rhithrogena genus in Europe.

Investigations of material collected partly in 1999 and mainly between 2006 and 2016 in New Guinea, mostly along the high, central mountain chain of the island, further increased our knowledge of the diversity of the genusLabiobaetisNovikova & Kluge on this island. Previously, 37 species were reported from New Guinea. We have identified six new species using a combination of morphology and genetic analysis (COI). They are described and illustrated based on their larvae. Five of the six new species belong to the grouppetersorum, which is endemic to the island. Additionally,Labiobaetis xeniolusLugo-Ortiz & McCafferty is also assigned to this group. The morphological characterisation of the grouppetersorumis enhanced, and a key to all species of this group is provided. Complementary descriptions and remarks to the morphology of known species of the grouppetersorumare provided. Additionally, a genetic analysis (COI) including most species and several additional Molecular Operational Taxonomic Units (MOTUs) of the grouppetersorumis discussed. One of the new species belongs to the groupvitilis. The morphological characterization of this group is slightly enhanced, and the obtained COI sequence was added to the genetic analysis of the grouppetersorum. The total number ofLabiobaetisspecies worldwide is augmented to 162.

We describe a new species of Prosopistoma collected in the High Atlas Mountains of Morocco. Prosopistoma maroccanumsp. nov. appears to be morphologically more similar to the European highly endangered P. pennigerum (Müller, 1785) than to the other Maghrebian species, P. alaini Bojkova & Soldán, 2015. A gene tree including the few available barcode sequences of Palearctic Prosopistoma specimens is provided. Possible affinities with West African species are also discussed.

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.