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Background The area sourrounding the Mediterranean basin is recognised as a major biodiversity hotspot for bees, and Italy is amongst the European countries with the highest bee species richness. Detailed knowledge of bee distribution is crucial for understanding bee biology and designing tailored conservation strategies, but is still insufficient in southern European countries, especially in Italy. New information We report recent finds of 48 bee species that yield significant novelties for the Italian bee fauna. Eight species, namely Andrena confinis Stöckhert, Anthidiellum breviusculum Pérez, Coelioxys alatus Foerster, Lasioglossum algericolellum Strand, Megachile lapponica Thomson, Megachile opacifrons Pérez, Megachile semicircularis auct. nec Zanden and Trachusa integra Eversmann are reported as new for Italy. In addition, Andrena binominata Smith, Andrena compta Lepeletier, Colletes acutus Pérez, Lasioglossum strictifrons Vachal, Rhodanthidium siculum Spinola and Rhodanthidium sticticum Fabricius are newly recorded from mainland Italy, Osmia heteracantha Pérez from Sardegna and Nomada flavopicta Kirby from Sicilia. We also report significant range extensions for other bee species and recent records of species that had long gone unrecorded in Italy. The combination of morphology and DNA barcoding provided reliable identifications even for the most challenging specimens. As several of our records come from areas neglected by bee experts in the past, this study stands out as a key indicator of a bee faunistic richness still awaiting discovery and hopefully it will stimulate the interest of taxonomists and stakeholders in pursuing bee research in Italy in the near future.

Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, social parasitism appeared in at least 3 subgenera independently: in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hyperboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main compounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.

Cold-adapted species are expected to have reached their largest distribution range during a part of the Ice Ages whereas postglacial warming has led to their range contracting toward high-latitude and high-altitude areas. This has resulted in an extant allopatric distribution of populations and possibly to trait differentiations (selected or not) or even speciation. Assessing inter-refugium differentiation or speciation remains challenging for such organisms because of sampling difficulties (several allopatric populations) and disagreements on species concept. In the present study, we assessed postglacial inter-refugia differentiation and potential speciation among populations of one of the most common arcto-alpine bumblebee species in European mountains, Bombus monticola Smith, 1849. Based on mitochondrial DNA/nuclear DNA markers and eco-chemical traits, we performed integrative taxonomic analysis to evaluate alternative species delimitation hypotheses and to assess geographical differentiation between interglacial refugia and speciation in arcto-alpine species. Our results show that trait differentiations occurred between most Southern European mountains (i.e. Alps, Balkan, Pyrenees, and Apennines) and Arctic regions. We suggest that the monticola complex actually includes three species: B. konradini stat.n. status distributed in Italy (Central Apennine mountains), B. monticola with five subspecies, including B. monticola mathildis ssp.n. distributed in the North Apennine mountains; and B. lapponicus. Our results support the hypothesis that post-Ice Age periods can lead to speciation in cold-adapted species through distribution range contraction. We underline the importance of an integrative taxonomic approach for rigorous species delimitation, and for evolutionary study and conservation of taxonomically challenging taxa.

DNA barcoding is well-known to support morphological species identification and it can be helpful for unveiling unexpected populations divergence patterns, especially in the context of the impacts on species posed by global change. In this note, we provided the first Italian record of the alpine mining bee Andrena allosa Warncke, 1975, confirmed with DNA barcoding. In addition, genetic identification of a specimen of Andrena praecox (Scopoli 1753) from western Italy pointed to an unexpected intraspecific genetic structuring at COI DNA barcoding region, with sequences from the Italian and the western sector of its global distribution differing 2.22% (p-dist) from populations of the eastern sector. Given the relevance of these records and of the genetic identity of bee populations from Italy, we argue that implementing molecular surveys in bee monitoring would surely contribute to the conservation of these important pollinators.

Climate change is threatening species and habitats. Altitudinal shifts uphill and negative population trends are commonly observed in altitude-related taxa. The bumblebee Bombus alpinus (Linnaeus, 1758) has a disjoint distribution restricted to Fennoscandia and the Alps, and is considered threatened. We studied the ecology and distribution of B. alpinus in the Alps, where the endemic subspecies Bombus alpinus helleri Dalla Torre 1882 is found, as a case-model because of its rarity, habitat, and mutual dependence with the ecosystem for pollination and resources. We developed species distribution models including both climatic and habitat variables to obtain the surface suitable for this subspecies and quantified its protected portion. Our analyses indicate that this bumblebee is restricted to the upper altitudes and has a narrow niche mainly related to the presence of glaciers, the cool temperature, a low temperature variation, and a specific range of precipitation. A strong altitudinal shift is also taking place probably due to climate change. After years of no changes in altitudinal distribution, its lowest altitudinal limit has moved up 479 m since the year 1984, while its upper altitudinal limit has remained unchanged. Over half of the suitable area in the Alps is included within protected areas, but conservation has not been planned yet. However, rare species with narrow niche, such as B. alpinus, are highly threatened by climate change. Potential short-term mitigation actions are discussed, including exchange of males between locations and integral protection of prairies in the vicinity of glaciers.