Apis fuliginosa Panzer, 1798: 16. Nomen praeoccupatum (not Apis fuliginosa Scopoli, 1770; not Apis fuliginosa Christ, 1791).
Heriades rapunculi Lepeletier, 1841: 406. Type material: ♀, (France), depository of type material unknown.
Heriades nigricornis Nylander, 1848: 269. Type material: Syntypes ♂♀, “in Fennia” (Finland), depository of type material unknown. Type species of Gyrodromella Michener. Synonymy in Benoist (1928).
Chelostoma inerme Eversmann, 1852: 74. Type material: Syntypes ♂♀, “in promont. Uralensib., in provinciis Orenburgensi et Simbirscensi” (Russia), Russian Academy of Sciences St. Petersburg. Synonymy in Schwarz et al. (1996).
Heriades casularum Chevrier, 1872: 505. Type material: Syntypes ♀♀, “Environs de Nyon” (Switzerland), Muséum d’Histoire Naturelle Genève or Natural History Museum Basel. Synonymy with Heriades nigricornis Nylander in Schletterer (1889).
Chelostoma proximum Schletterer, 1889: 643. Type material: Holotype ♂, “Transkaukasien (Kussari)” (Azerbaijan), Natural History Museum Wien. New synonymy (see Note).
Osmia (Acanthosmia) archanensis Cockerell, 1928: 353. Type material: Holotype ♀, “Archan” (Russia), Natural History Museum London. Synonymy with Chelostoma fuliginosum (Panzer) in Tkalcu (1967).
Osmia (Acanthosmia) platyodonta Cockerell, 1928: 352. Type material: Holotype ♂, “Irkutsk” [Russia], Natural History Museum London. Synonymy with Chelostoma fuliginosum (Panzer) in Tkalcu (1967).
Heriades confusa Benoist, 1934: 158. Type material: Lectotype ♂, by designation of G. van der Zanden, “Environ d’Alger” (Algeria), Muséum National d’Histoire Naturelle Paris. New synonymy (see Note).
Distribution. Widespread in the Palaearctic region, from the Maghreb (Morocco, Algeria) and the Levant (Israel and Palestine, Jordan and Syria) northwards over the whole of Europe (except Norway) up to northern Finland (northernmost record south of Inari 68.44 °N, 27.36 °E), and from Turkey and the Caucasus (Azerbaijan, Georgia) eastwards to Iran, Central Asia (Kazakhstan, Kyrgyzstan, Turkmenistan, Uzbekistan), China, Mongolia and Far eastern Russia. The species has been introduced into the Nearctic region and occurs in a small region encompassing northeasternmost USA and southeastern Canada (Ascher and Pickering, 2014).
Pollen hosts. Oligolectic on Campanula (Campanulaceae) and possibly also on closely related genera (Fig. 3; Amiet et al., 2004, Sedivy et al., 2008, Westrich, 1989). In fact, the species epithet “ rapunculi ” and the vernacular name “Hériade de la raiponce” both given by Lepeletier (1841) refer to Phyteuma, suggesting that flowers of this Campanulaceae genus might occasionally be exploited by C. rapunculi in addition to Campanula.
Nesting biology. Nesting sites are preexisting linear cavities such as insect burrows and drilled borings in dead wood or bark, hollow stems (e.g. reed, bamboo), drilled borings in stems or glas tubes (Benoist, 1929; Bonelli, 1967; Brechtel, 1986; Käpylä, 1978; Ruszkowski et al., 1995; Stoeckhert, 1933; Westrich, 1989). Inside these narrow cavities, one to several brood cells are arranged in a linear series (Fig. 1). Cell partitions and nest plug are made of mud mixed with nectar and probably also saliva (Westrich, 1989). Small pebbles, sand grains and other particles are embedded in the outer surface of the nest plug (Fig. 2).
Note. The shape of male tergum 7 was hitherto assumed to be the only reliable character for the discrimination of the widespread C. rapunculi from C. confusum and C. proximum, which have been described based on specimens collected in northern Africa and the Caucasus, respectively. The examination of a large number of specimens of C. rapunculi, however, revealed a considerable intraspecific variability in the shape of tergum 7 on the one hand and gradual transitions in the shape of tergum 7 between these taxa on the other hand. Specifically, i) the lower median tooth of tergum 7 gradually gets narrower and shorter towards northern Africa and the Levant resulting in the relatively small lower tooth considered typical for C. confusum, and ii) the upper lateral teeth gradually get wider and increasingly fuse with each other and with the lower median tooth towards eastern Turkey and the Caucasus resulting in the straight transverse apical margin of tergum 7 considered typical for C. proximum.
Due to this clinal variation, which eliminates the morphological gaps previously assumed to exist between the three taxa, and the absence of any other clear characters separating C. rapunculi, C. confusum and C. proximum in either sexes, these three taxa are considered here to be conspecific, representing a single widespread and morphologically variable species.