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).

Northwest African material previously ascribed to the subspecies Nephrotoma guestfalica surcoufi (Pierre, 1925) proved to belong to two distinct morphological forms, the true N. g. surcoufi from Algeria, and Tunisia, and the here newly introduced Nephrotoma guestfalica vaillanti n. subsp. from Morocco. With the distinction of the new form, four subspecies of Nephrotoma guestfalica (Westhoff, 1879) are now recognized, all occurring in the western Palaearctic. An identification key for the males of the four taxa of Nephrotoma guestfalica s.l. is provided. The male terminalia of the four taxa are illustrated. The distribution of the four subspecies is summarized, based on material examined and published data. A map showing the currently known distribution of N. guestfalica surcoufi and N. guestfalica vaillanti is presented. Nephrotoma guestfalica guestfalica is recorded here for the first time from Croatia.

An overview of the Tipulidae known to occur in northern Morocco with an emphasis on the Rif mountains is given, incorporating new distribution data based on recently collected material in the area. Dolichopeza (Dolichopeza) hispanica, Tipula (Lunatipula) subpustulata, and Tipula (Yamatotipula) afriberia afriberia are recorded for the first time for the Rif. Tipula (L.) stimulosa Mannheims, 1973 and T. (Vestiplex) vaillanti vaillanti Theowald, 1977 are reported for the first time for the Rif and Morocco. Tipula (Lunatipula) pseudocinerascens Strobl, 1906 and Tipula (Savtshenkia) confusa van der Wulp, 1883 are recorded for the first time for the Rif, Morocco and North Africa. A new species of the subgenus Lunatipula, T. (L.) pjotri n. sp., is described and illustrated. Nephrotoma exastigma, previously reported for the Rif, seems to be absent in Morocco. Reports of Tipula (Emodotipula) obscuriventris Strobl, 1900 for Morocco actually refer to T. (E.) leo. This brings the number of Tipulidae for Morocco to 39 species and for the Rif to 28. An updated checklist of the Tipulidae of Morocco is provided.

New data on the Chironomidae (Diptera) of the Rif (Northern Morocco): New collections of pupal exuviae of chironomids in various fresh water ecosystems in the Rif in the north of Morocco revealed an interesting inventory. The chironomid community collected is diverse enough and interesting, and rare species are present. Of a total of 141 identified taxa, 46 species have proved to be new for the Rif and 31 for Morocco. The chorological tendency is mainly Palaearctic and Mediterranean. The majority of the sites investigated belong to protected areas in the north of Morocco, such as SIBE Jbel Moussa, SIBE Jbel Tidirrhine, SIBE Jbel Bouhachem and Talassemtane National Park, which belong to the Intercontinental Reserve of the Mediterranean Biosphere.