Further revisions to the Palaearctic Andrena fauna (Hymenoptera: Andrenidae)

Andrena is the second largest genus of bees, with around 1,700 species known globally following recent revisions (e.g. Wood & Monfared 2022; Pisanty et al. 2022a; Wood 2023a; b; c; d). The genus is relatively young at approximately 25 million years old, and is known for its explosive radiation as one of if not the most rapidly speciating bee lineages (Bossert et al. 2022; Pisanty et al. 2022b). This rapid rate of speciation combined with a preference for Mediterranean and xeric environments means that a large number of Andrena species remain undetected and undescribed, most clearly in difficult-to-access parts of the Middle East and Central Asia. The genus has a long history of study, particularly in the West Palaearctic (Gusenleitner & Schwarz 2002), and there are consequently a large number of original works describing taxa from across the Old World (e.g. Christ 1791; Panzer 1799; Erichson 1835; Smith 1853; Dours 1873; Morawitz 1876; Schmiedeknecht 1882–1884; Radoszkowski 1891; Nurse 1904; Cameron 1908; Friese 1914; Perkins 1914; Cockerell 1917; Strand 1921; Stöckhert 1935; Noskiewicz 1939; Warncke 1965; Osytshnjuk 1995; Xu et al. 2000; Grünwaldt et al. 2005; Tadauchi et al. 2005). Though workers often corresponded, the huge diversity of species and the often subtle characters separating them means that many taxa are synonymous or present other nomenclatural challenges, but this still remains to be established for many taxa despite historical and contemporary revisionary works (e.g. Warncke 1967; Tadauchi & Xu 1999; 2003; Gusenleitner & Schwarz 2002; Xu et al. 2000; Xu & Tadauchi 2002; 2005; 2009; 2012; Gusenleitner et al. 2005; Pisanty et al. 2018; Astafurova et al. 2022a; 2023; Praz et al. 2022; Wood & Monfared 2022; Wood 2023a; b; c). Against this context, revisionary works on Old World Andrena must balance i) the long history of species description and subsequent use, often with unclear or inconsistent species concepts; ii) the rapid speciation rate of Andrena combined with their often sporadic appearance and highly local distributions leading to enormous species diversity, and iii) the ongoing and incomplete treatment of older names, some of which have not been revised due to inability to locate types or inability to visit specific collections. The present work represents an additional contribution to this ongoing work through resolving existing nomenclatural problems and describing or elevating distinct Old World Andrena species.