Osmia cinctella regarded as nomen dubium
Osmia cinctella was described by Dours (1873) based on specimens both from Greek islands (probably Crete) and Algeria. Based on the original description, Osmia cinctella belongs to the Osmia niveocincta species group. Among the representatives of this group, Osmia niveocincta Pérez, 1879 is the only species known to occur both on Crete and in Algeria. However, several characters given in the original description of Osmia cinctella clearly exclude Osmia niveocincta, suggesting that Dours’ syntypes comprised two different species. Most probably, Dours’ specimens from the Greek Islands correspond to Osmia dives Mocsaryi, 1877 and those from Algeria to Osmia frieseana Ducke, 1899. Unfortunately, the types of Osmia cinctella are lost (Tkalcu, 1977b; Zanden, 1990), rendering both the clarification of the species identity and the designation of a lectotype impossible. Thus, O. cinctella is regarded here as a nomen dubium.
Warncke (1988a) considered the Cretean specimens of “Osmia cinctella” (as O. sogdiana cinctella) to be taxonomically different from those of Osmia dives (as O. sogdiana dives). In fact, the specimens from Crete are slightly smaller and have a slightly finer and denser punctation of female terga 1-2 compared to Osmia dives from mainland Europe and Turkey. As these morphological differences are only very minor, however, the Cretean specimens are considered here to be conspecific with Osmia dives.