Unexpected levels of cryptic diversity in European bees of the genus Andrena subgenus Taeniandrena (Hymenoptera, Andrenidae): implications for conservation

Using a combination of DNA barcodes and morphology, we examine species boundaries in bees of the genus Andrena subgenus Taeniandrena in Europe. First, we solve the long controversy surrounding the status of Andrena ovatula (Kirby, 1802) and A. albofasciata Thomson, 1870, proposed to represent distinct species nearly 100 years ago, but mostly treated as conspecific in recent studies. Our results unambiguously support the presence of two taxa that are often found in sympatry: the first taxon, referred to as A. ovatula, is present in Northern Europe but also in Southern Europe along the Mediterranean coast; the second taxon is referred to as A. afzeliella (Kirby, 1802), stat. rev., with A. albofasciata considered to be a junior synonym (syn. nov.), and is widely distributed in Europe. Second, we show that another widely distributed species has hitherto been overlooked in Europe: A. ovata Schenck, 1853, stat. rev. Third, we demonstrate that two taxa currently treated as subspecies should be given specific rank due to significant morphological and genetic differences: A. croceiventris Morawitz, 1871, stat. rev., so far treated as a subspecies of A. similis Smith, 1849, and A. vocifera Warncke, 1975, stat. nov., so far treated as a subspecies of A. gelriae van der Vecht, 1927. Both A. croceiventris and A. vocifera have particularly restricted ranges in Europe, being known only from central to southern Italy and Sicily, and continental France, respectively. Fourth, we describe a new species from Sardinia and Corsica, A. antonellaesp. nov. Lastly, the following new synonymies are proposed: A. similis, A. ocreata cyprisina Warncke, 1975 and A. similis caraimica Osytshnjuk, 1994 are placed in synonymy with A. russula Lepeletier, 1841 (syn. nov.); A. fuscata (Kirby, 1802), A. canescens Schenck, 1853 and A. pseudovatula Alfken, 1926 are placed in synonymy with A. afzeliella (syn. nov.). Lectotypes are designated for A. afzeliella, A. fuscata (Kirby, 1802), A. ovata and A. wilkella (Kirby, 1802). Our results suggest a particularly fast diversification in this group of bees, leading to the presence of numerous species exhibiting particularly restricted geographic ranges. We discuss the implications for conservation of this astonishing cryptic diversity in European bees.