Lost type specimens reveal a Spanish bee thought to span Asia is an Iberian endemic

A bee described from southern Spain more than 150 years ago and long believed to stretch in a fragmented arc from Iberia across southeastern Europe to Central Asia turns out to live nowhere but Spain. In a new revision published in the Deutsche Entomologische Zeitschrift, taxonomist Thomas J. Wood untangles the identity of Nomiapis valga, a member of the sweat bee family Halictidae, and shows that the eastern populations attributed to it for decades actually belong to a separate species, Nomiapis caucasica, which is here formally resurrected from synonymy. The study also delivers the first modern identification key to all eleven European species of the genus, a tool that should end a long era of misidentification.

The confusion is rooted in the peculiar biology of the subfamily Nomiinae, a group of roughly 620 species whose center of diversity lies in the Afrotropics. Nomiine bees are famous for their extravagant morphology, especially in males, which often sport enormously inflated hind legs armed with pointed processes and squamous hairs, alongside striking variation in coloration ranging from dark integument to iridescent metallic sheens. That exuberance has fueled endless disagreement about how to divide the group into genera. But the real bottleneck, the new study argues, sits at the species level, and above all in the females, which are comparatively uniform and notoriously difficult to tell apart. Because many historical records rest on female specimens alone, geographic ranges have been drawn on shaky foundations.

Nomiapis valga was described by Gerstäcker in 1872 from Andalusia, yet its type material has been lost, and the scarcity of Spanish specimens in collections led earlier researchers to question whether the type locality was even correct. Klaus Warncke, in his influential 1976 revision, treated the Caucasus-dwelling Nomiapis caucasica, described by Friese in 1897, as merely a subspecies of valga, while David Baker in 2002 went the other way and sank caucasica into a different species, N. equestris. Both hypotheses were handicapped by the same problem: the type material of caucasica was also considered lost. Without type specimens to anchor the names, generations of identifications drifted.

The breakthrough came from detective work in museum drawers. Friese had stated in his original description that four males of caucasica from the Caucasus region, collected at Araxesthal in 1890, were held in the Museum Wien. Searches in Vienna in 2024 came up empty, but a loan form dated April 1965 surfaced, documenting a loan of 38 nomiine specimens to M.A. Diniz at the University of Coimbra. Enquiries in Portugal could not locate them either. The missing specimens were finally found somewhere unexpected: three of them, bearing Friese’s own labels reading Nomia caucasica and the original collecting data, were discovered in the Warncke collection at the Oberösterreichisches Landesmuseum in Linz, where Warncke had even added handwritten paratype labels, showing he knew exactly what they were. It remains unclear when he removed them from Vienna. One of the three is now designated the lectotype and the series has been returned to the Naturalhistorisches Museum Wien.

With the type finally in hand, both earlier hypotheses could be tested against the specimen itself. Baker’s synonymy with N. equestris collapses immediately: the lectotype’s fourth sternum bears a deep semi-circular excavation and the fifth sternum carries two pincer-like, slightly bent digitiform projections, whereas male equestris have a narrowly incised fourth sternum, a large circular excavation on the fifth, and a narrow, sharply pointed hind tibial process. Distinguishing caucasica from valga proved subtler, but a consistent suite of characters emerged. Males of caucasica show relatively sparse punctures on the second tergum with two shining areas larger than a puncture diameter, only a very narrow basal row of punctures on the marginal areas of the second and third terga, weak microsculpture giving broadly shining terga, and a scutellum that is laterally rounded. Spanish valga males, by contrast, are densely punctured on the second tergum, carry three to four rows of basal punctures on the marginal areas, have slightly stronger microsculpture and duller terga, and possess a scutellum with small posteriorly projecting teeth.

DNA evidence reinforces the split. The study generated the first genetic barcodes for several European Nomiapis species, targeting the mitochondrial COI region with standard Sanger sequencing at the Canadian Center for DNA Barcoding and, for additional material, Oxford Nanopore long-read sequencing processed through a reproducible Snakemake pipeline. In a maximum likelihood tree built with 1000 bootstrap replicates, valga, caucasica, and the steppe species N. femoralis each form distinct subclades within a well-supported femoralis group. Valga and caucasica differ by an average genetic distance of 2.44 percent, comparable to the 4.84 to 5.02 percent separating them from femoralis, and each species clade carries bootstrap support above 80. Morphology, biogeography, and molecules now point the same way.

The taxonomic consequences ripple outward through the literature. Because valga is now restricted to Spain, with confirmed populations concentrated in the provinces of Granada and Málaga plus an old record from Zaragoza, every record of valga from Greece, Turkey, the Levant, Central Asia, and Pakistan must instead refer to caucasica, whose documented range extends from North Macedonia and Greece through Turkey, Cyprus, Israel, Jordan, Armenia, Azerbaijan, Iran, and across Central Asia to Pakistan. Since valga’s original types are lost, the author designated a male neotype from Granada, within the original type locality, to permanently fix the name to the Spanish populations. Re-examination of specimens behind published records also cleaned up the map: two males once reported from Czechia as valga are actually femoralis, and records from Iran and Afghanistan attributed to valga belong to caucasica. A puzzling Barcelona record is provisionally assigned to valga, meaning femoralis must be excluded from the Spanish fauna.

The study also strengthens the case for Nomiapis susannae, described only in 2018 from Greece, as a valid species. Barcoded specimens of susannae differ from the widespread N. diversipes by an average of 1.86 percent, a distance exceeding the maximum intraspecific variation within diversipes itself, and the sequenced susannae male was caught in sympatry with three diversipes males carrying identical sequences near Kavala in eastern Macedonia. Combined with the morphological criteria of the original description, the two taxa are best kept separate, though the female of susannae remains unknown and its full range needs clarification.

Perhaps the most sobering finding concerns N. femoralis, a bee of Eurasian steppe grasslands. Across Central Europe it has not been seen for decades: the last Austrian record dates to 1954, Czechia’s to 1958, Serbia’s to 1958, and Slovenia’s to 1964, although the species persists in Hungary, where it was collected in 2024. This pattern matches the well-documented decline of Pannonian and steppic insects following the intensification of agriculture after the Second World War, a syndrome familiar from bumble bees but previously obscured for Nomiapis by taxonomic uncertainty. With species boundaries now clear, a concrete conservation assessment becomes possible for the first time.

Beyond the immediate revisions, the work carries a broader message about the state of bee taxonomy even in well-studied Europe. That the identity and distribution of a genus with only eleven European species could remain so muddled through successive revisions is a testament to how much alpha-level taxonomy still depends on lost types, copied descriptions, and unexamined synonymies. It also underlines the Iberian Peninsula’s standing as a major center of endemic bee diversity. The author notes that similar problems almost certainly lurk in the Indo-Malayan tropics, where many nomiine species were described from females alone and some genera have never been modernly revised. The encouraging counterpoint is that, with careful attention to puncture density, integumental sculpture, association with males, biogeography, and DNA barcodes, even the most intractable female specimens can now be identified with confidence, offering a template for untangling the rest of the world’s nomiine bees.

Subject of Research: Taxonomic revision and distribution of the nomiine bee genus Nomiapis in Europe, including resurrection of Nomiapis caucasica and restriction of Nomiapis valga to Spain

Article Title: On the status of Nomiapis valga (Gerstäcker) and its distribution ( Hymenoptera , Halictidae , Nomiinae ), with an identification key for European Nomiapis

Article References: Wood, T. J. (2025). On the status of Nomiapis valga (Gerstäcker) and its distribution (Hymenoptera, Halictidae, Nomiinae), with an identification key for European Nomiapis. Deutsche Entomologische Zeitschrift, 72(1), 85-100. https://doi.org/10.3897/dez.72.153052

Image Credits: AI Generated

DOI: 10.3897/dez.72.153052

Keywords: Nomiapis valga, Nomiapis caucasica, Halictidae, Nomiinae, bee taxonomy, type specimens, neotype, DNA barcoding, COI gene, Iberian endemic, museum collections, species delimitation