We revise the Merodon constans species group of the genus Merodon Meigen, 1803 (Diptera: Syrphidae), provide morphological diagnosesand descriptions, as well as an illustrated key and a discussion on the different taxonomic characters used. In total, 15 species were studied, their geographic distributions are presented on maps, and nine new species are described. Two species are redefined and neotypes are designated, lectotypes are designated for five species, and onespeciesis reinstated as valid. Following a detailed study of type material in different entomological collections, the status of several species is revised and three new synonymies are proposed. The M. constans species group was resolved as being monophyletic within the M. albifrons lineage based on molecular analyses using COI and 28S rRNA gene sequences. Three species morphologically similar to M. constans (Rossi, 1794) but occurring outside its distributional rangewere supported as being valid and distinct species on the basis of molecular data, but they were not distinguishable based on morphological characters. By contrast, continental populations of M. analis Meigen, 1822 could not be separated from Mediterranean M. constans based on differences in COI or 28S rRNA genes. The same molecular markers could not discriminate between two other species pairs. We conclude that these molecular markers only partially resolve species within the M. constans group. Geometric morphometry of wing shape successfully separated M. analis and M. constans, as well as M. spineus Vujić, Šašić Zorić & Likov, sp. nov. in both species and population analyses.

The hemiparasitic European mistletoe, Viscum album L. (Viscaceae), displays a rapid and remarkable expansion into natural and urban ecosystems in Ukraine. The monitoring and management of this rapidly spreading species is increasingly difficult as new plant species become hosts. Unlike other local mistletoe species, the European mistletoe has a broad distribution and thus requires a countrywide pest status assessment for control. This review outlines the major taxonomic and evolutionary issues pertinent to V. album with an emphasis on the characters used to distinguish its five currently recognized subspecies. The review also provides an updated distribution map and host range for the three V. album subspecies in Ukraine (V. album subsp. album, V. album subsp. abietis (Wiesb.) Janch. and V. album subsp. austriacum (Wiesb.) Vollm.), addressing the current knowledge of their biology and ecology. A significant portion of the paper is devoted to the diversity of V. album associated organisms including herbivores, endophytes, and parasites, drawing particular attention to major pollination and dispersal vectors as well as potential biocontrol agents of this mistletoe species.

The faunistic knowledge of the Diptera of Morocco recorded from 1787 to 2021 is summarized and updated in this first catalogue of Moroccan Diptera species. A total of 3057 species, classified into 948 genera and 93 families (21 Nematocera and 72 Brachycera), are listed. Taxa (superfamily, family, genus and species) have been updated according to current interpretations, based on reviews in the literature, the expertise of authors and contributors, and recently conducted fieldwork. Data to compile this catalogue were primarily gathered from the literature. In total, 1225 references were consulted and some information was also obtained from online databases. Each family was reviewed and the checklist updated by the respective taxon expert(s), including the number of species that can be expected for that family in Morocco. For each valid species, synonyms known to have been used for published records from Morocco are listed under the currently accepted name. Where available, distribution within Morocco is also included. One new combination is proposed: Assuania melanoleuca (Séguy, 1941), comb. nov. (Chloropidae).