Halictus (Monilapis) compressus (Walckenaer, 1802) and Halictus (Monilapis) eurygnathus Blüthgen, 1930

The use of these two names to refer to the same species has a very long running and complex taxonomic history. In short, this relates to different interpretations of the name Apis flavipes Panzer, 1798 (a junior primary homonym and hence unavailable) and how to treat the replacement name Andrena compressa Walckenaer, 1802 .As there is no clearly correct answer, and there are valid arguments presented by those who favour each name (e.g. Warncke 1973; Ebmer 1974; 1988a; Pesenko 1985), a case has been written and it is under review by the ICZN (Wood et al.; case number: 3907). This case will be published in the next edition of the Bulletin of Zoological Nomenclature (D. Whitmore, pers. comm.). This case argues that Pesenko’s designation of a neotype for Apis flavipes (and hence for Andrena compressa) went against prevailing usage at the time; during the time that the case is considered and subsequently voted on by the Commission, the name Halictus eurygnathus can continue to be used for this species. We therefore use H. eurygnathus for the European species, and await a final ruling from the ICZN which will provide clarity and certainty for this long running debate. For the publication date, we follow the argument of Scheuchl et al. (2023).