Female of Osmia (Tergosmia) tergestensis Ducke, 1897 biting off a petal of Geranium pyrenaicum used to construct the brood cells. Foto A. Krebs.

Historical development

The first taxonomic treatment of the Palaearctic osmiine bees dates back to the end of the 19th century when Schmiedeknecht (1885-1886) provided the first monograph on the European representatives of the Osmiini. In 1896, Dalla Torre published his monumental catalogue of the Hymenoptera of the world, which is still an invaluable source for the taxonomic literature on the osmiine bees of the 18th and 19th century. The third landmark study in the taxonomic inventory of the Palaearctic Osmiini was the monograph of Ducke (1900) covering all Palaearctic species known by the end of the 19th century. With its extensive species descriptions and identification keys, this monograph was the first comprehensive taxonomic treatment of the Palaearctic osmiine bees, and it has indeed remained the last up to this day. In the 20th century many new osmiine bee species were described and many names put into synonymy by taxonomists such as J.D. Alfken, R. Benoist, T.D.A. Cockerell, C. Ferton, H. Friese, T. Griswold, V. Haeseler, F.F. Kohl, G.A. Mavromoustakis, J. Pérez, D.S. Peters, V.B. Popov, E. Stanek, B. Tkalcu, K. Warncke, Y. Wu, G. van der Zanden and others. Though Griswold (1985) did not revise the Heriades group down to species level, he nevertheless included a list of all species belonging to this group. Zanden (1988b) summarized the taxonomic findings of these authors by providing a list of names of the Palaearctic osmiine bee species including synonyms and short distributional notes. Even though several taxa, such as Chelostoma, Heriades, Hofferia, Protosmia (Chelostomopsis) and Stenoheriades, were not addressed, this concise list represents an important synopsis of the Palaearctic osmiine bees. Recently, a taxonomic catalogue on the Palaearctic osmiine bees was published (Ungricht et al., 2008), covering all family-, genus- and species-group names as published by the end of 2006.

While a modern and comprehensive monograph covering all Palaearctic Osmiini is still lacking, several osmiine genera or subgenera were partially or completely revised at species-group level. These revisions, which are generally restricted to Europe or the western part of the Palaearctic, are listed below for the different osmiine taxa.

ChelostomaSchletterer (1889)

Chelostoma (Foveosmia): Warncke (1991c); Schwarz and Gusenleitner (2000)

Chelostoma (Gyrodromella): Müller (2015b)

Haetosmia: Peters (1974); Müller & Griswold (2017)

Heriades: Schletterer (1889)

Hofferia: Müller & Trunz (2014)

Hoplitis (Alcidamea): Warncke (1991h)

Hoplitis (Chlidoplitis): Müller (2014a)

Hoplitis (Formicapis): Müller & Mauss (2016)

Hoplitis (Hoplitis): Morice (1901); Warncke (1991e, f, 1992a); Müller (2016)

Hoplitis (Megahoplitis): Müller (2014a)

Hoplitis (Pentadentosmia): Warncke (1991a)

Hoplitis (Platosmia): Warncke (1990); Müller (2015a)

Hoplitis (Stenosmia): Warncke (1991b); Müller (2014b)

Hoplitis (Tkalcua): Müller & Mauss (2016)

Ochreriades: Griswold (1994b)

Osmia (Helicosmia): Tkalcu (1975c); Warncke (1988a)

Osmia (Hemiosmia): Tkalcu (1975b); Haeseler (2005)

Osmia (Hoplosmia): Tkalcu (1974a); Müller (2018a)

Osmia (Melanosmia): Tkalcu (1983)

Osmia (Neosmia): Tkalcu (1977a)

Osmia (Osmia): Peters (1978a); Müller (2012b)

Osmia (Pyrosmia): Zanden (1991a); Warncke (1992b)

Osmia (Tergosmia): Warncke (1988b)

Protosmia (Chelostomopsis): Müller (2017)

Stenoheriades: Müller & Trunz (2014)

Current status and outlook

Starting with Linnaeus (1758), who described four osmiine bee species, a total of 99 mainly European taxonomists contributed to the available species-group names by the end of 2006 (Ungricht et al., 2008). The taxonomists who described the highest number of species-group taxa are K. Warncke (98 valid names, 11 synonyms), F. Morawitz (73, 21), R. Benoist (52, 40), J. Pérez (51, 33), G. van der Zanden (52, 14), B. Tkalcu (52, 10), H. Friese (33, 13), Y. Wu (33, 1), A. Müller (33, 1), G.A. Mavromoustakis (29, 4), J.D. Alfken (15, 9), D.S. Peters (16, 2) and V.B. Popov (16, 1). The most productive periods in terms of described osmiine bee species and subspecies were from 1870–1910 (207 valid names, 107 synonyms) and from 1970–2006 (264, 24), largely coincident with the creative careers of the above-mentioned taxonomists.The present situation of bee taxonomy of the Palaearctic region in general was discussed in some detail by Ebmer (1994) and O’Toole (1996), depicting a field in dire need of a coordinated effort to work up the old literature and close the innumerable gaps in our taxonomic knowledge. Unfortunately, the taxonomy of the Palaearctic osmiine bees is not in a better state than bee taxonomy in general. This is best exemplified by the fact that for 111 Palaearctic osmiine species (18% of the total) only one sex is currently known as well as by the high number of species descriptions based solely on a single specimen. It must be expected that many tentatively accepted osmiine bee taxa will prove to be synonyms once more specimens become available for study. On the other hand, there exist about 100 undescribed Palaearctic osmiine bee species and others undoubtedly still await discovery. In addition, single osmiine species will certainly prove to represent multiple species complexes with the application of molecular methods (Packer and Taylor, 1997). Some osmiine genera and subgenera have been revised at species-group level (see above). However, most of these revisions only treat part of the taxon in question or are geographically limited. For other taxa, no recent revisions exist at all. Among the osmiine bee taxa most urgently needing revisional work are Chelostoma, Heriades, Hoplitis (Hoplitis), Hoplitis (Anthocopa) and Protosmia as well as some species groups within Osmia (Helicosmia).