The story began in May 2024, when a single male A. onosmarum was captured in Bulgaria visiting flowers of the plant genus Onosma, a group of Boraginaceae known for their deep, tubular blossoms. Just weeks later, in June 2024, a targeted search in northern Greece revealed a thriving population: roughly ten males and five females patrolling and feeding among clumps of Onosma on dry slopes between 600 and 1000 metres above sea level. The researchers visited around twenty sites in the region, and the bee turned up at only one of them, hinting at how local and sporadic its appearance really is.

What makes the find even more striking is that the bee is not exactly small. A. onosmarum is a member of the genus Anthophora, which contains around 430 species worldwide and 77 in Europe, making it the seventh largest bee genus on the continent. A bee of this size, with distinctive yellow facial markings in the male and a metasoma covered in either pale yellow-orange or black pubescence in the female, somehow slipped past generations of European entomologists. The researchers suspect that the species was simply overlooked, mistaken for other similar-looking Anthophora or not recognised because no modern identification key exists for the genus in south-eastern Europe.

Museum collections helped fill in the picture. Searches turned up 23 previously unidentified specimens, including a male collected in Bulgaria as far back as 1987, sitting undetermined in the collection of the Oberösterreichisches Landesmuseum in Linz, Austria. The other specimens came from Turkey, Iran, and Georgia, confirming that the species is widespread across the Anatolian plateau and beyond. With altitude data available for some records, the bee is known to occur between 420 and 2200 metres above sea level, with most records above 1000 metres.

To confirm the identification, the team generated a full-length DNA barcode from a Greek male specimen. When compared against the Barcode of Life Data System, the closest matches were to other Anthophora species, but the barcode was clearly distinct from all others represented in the database. Tree-based analysis tentatively suggested that A. onosmarum is sister to a clade containing A. balneorum and A. nigrovittata, offering a first glimpse of its phylogenetic affinities.

The behavioural observations are perhaps the most exciting part of the story. The researchers watched females hang upside down from Onosma corollas, using their remarkably long tongues to reach the nectaries deep inside the flowers. Then came the buzz. The females were heard emitting a short, high-pitched vibration while gripping the flower tightly, and pollen could be seen falling onto the underside of their metasoma as they released their grip. This is buzz pollination, a technique more commonly associated with bumblebees, and it allows the bee to shake pollen loose from the anthers in a way that scraping alone cannot achieve.

Based on this behaviour, the bee’s long tongue, and its strong association with Onosma, the researchers consider A. onosmarum likely to be narrowly oligolectic, meaning it depends on a single plant genus for pollen. This kind of specialisation makes the bee vulnerable to changes in the availability of its host plant, and it also makes the discovery ecologically significant. Other Boraginaceae-associated bees show a range of strategies, from the broadly oligolectic Osmia apicata, which scrapes pollen with its forelegs, to buzz-pollinating specialists like Hoplitis onosmaevae and Eucera breviceps, which seem to be narrow oligoleges of Onosma.

The colour variation observed in females adds another layer of intrigue. Of nine female specimens examined, four showed black pubescence and five showed yellow pubescence, with a weak geographic gradient of darker individuals in the west and lighter ones in the east. Remarkably, two females of different colour morphs were collected at the same site in Turkey on separate occasions. The researchers make no decisive comments on the cause, noting only that the variation seems to be simple colour polymorphism, not accompanied by structural differences. Males, by contrast, appear much more consistent in colouration, fitting a broader pattern of reduced colour variation in male anthophorines.

The discovery fits into a growing trend. In recent years, several bee species with Caucasian, Anatolian, or Middle Eastern distributions have been turning up in under-surveyed mountainous parts of the Southern Balkans. The newly described Hoplitis onosmaevae, ranging from southern France to Turkey and northern Iraq, and the eucerine bee Eucera breviceps, newly reported for western Europe, both tell a similar story. The researchers suggest that A. onosmarum is almost certainly present in Albania and North Macedonia as well, given its known locality in north-western Greece.

For now, the bee remains rare and local in the Balkans, despite the wide distribution and abundance of its host plants. The researchers hope that a revised identification key to European Anthophora will be produced in the near future, making it easier for others to recognise this and other overlooked species. In the meantime, the discovery serves as a reminder that even large, distinctive bees can hide in plain sight, waiting for someone to look closely at the right flowers on the right dry slope at the right time of year.

Subject of Research: Discovery of Anthophora onosmarum Morawitz, 1876 in Europe (Hymenoptera, Apidae)

Article Title: Discovery of Anthophora onosmarum Morawitz, 1876 in Europe ( Hymenoptera , Apidae )

Article References: Wood, T. J., & Praz, C. J. (2024). Discovery of Anthophora onosmarum Morawitz, 1876 in Europe (Hymenoptera, Apidae). Alpine Entomology, 8, 153-160. https://doi.org/10.3897/alpento.8.138225

Image Credits: AI Generated

DOI: 10.3897/alpento.8.138225

Keywords: bees, entomology, biodiversity, conservation, Europe, oligolectic, Discovery, Anthophora, onosmarum, Morawitz, Hymenoptera, Apidae