An unexpected new genus of panurgine bees (Hymenoptera, Andrenidae) from Europe discovered after phylogenomic analysis

Establishing a higher classification of bees based on morphology alone can fail to capture evolutionary relationships when morphological characters either vary very little between distantly related groups, or conversely vary greatly between closely related species. This problem is well represented in the subfamily Panurginae, for which a recent global revision based on phylogenomic data unexpectedly revealed that two Old World species previously placed in Camptopoeum Spinola and Flavipanurgus Warncke, are in fact most closely related to each other, and together form a sister group relationship to the remaining Flavipanurgus and Panurgus Panzer combined. To rectify this situation, we here establish an expanded phylogenomic data set of Old World Panurgini and re-assess generic and subgeneric concepts for the tribe. To solve the paraphyly of Camptopoeum and Flavipanurgus, we establish the new genus Halopanurgus gen. nov. containing the species H. baldocki (Wood & Cross), comb. nov. and H. fuzetus (Patiny), comb. nov., both of which are restricted to coastal sands, saltmarshes, and inland saline lagoons in the extreme south of Portugal and south-west of Spain. Re-evaluation of four recently used subgenera in Panurgus strongly supports a simplified classification of two subgenera; Pachycephalopanurgus Patiny, stat. rev. including Micropanurgus Patiny syn. nov., and Panurgus s. str. including Euryvalvus Patiny. Pachycephalopanurgus species seem to be oligoleges of Asteroideae (Asteraceae), whereas Panurgus s. str. may be oligoleges of Cichorieae (Asteraceae). Our findings reinforce the challenges of establishing a phylogenetically sound classification of Panurginae using morphology alone and illustrate that even in well-studied regions like Europe unrecognised genera can persist in underexplored corners of the continent.