Osmia aurulenta and O. tunensis

Tkalců (1970) treated the two closely related and morphologically very similar taxa Osmia tunensis (Fabricius, 1787) and Osmia aurulenta (Panzer, 1799) as different species. The original description of the two taxa was based on specimens from the Maghreb for O. tunensis and from central Europe for O. aurulenta. In contrast, Warncke (1988a) considered O. aurulenta to be a subspecies of O. tunensis, which was again rejected by Schwarz et al. (1996), who supported the view of Tkalců (1970).

North African specimens of O. tunensis differ from central and east European specimens of O. aurulenta by i) a slightly shorter vertex, ii) a slightly denser punctation of the scutum, iii) a longer pilosity on both discs and marginal zones of the terga, iv) a brightly foxy red rather than yellowish-red pilosity of scutum, scutellum, mesepisternum and terga, which is of about the same colour as the metasomal scopa in the female, and v) a yellowish(-red) rather than whitish pilosity of face, underside of mesosoma and tergum 1 in the male. Specimens from Sicily and Malta have characters iii)-v) in common with north African specimens, whereas they have a similarly long vertex and a similarly dense punctation of the scutum as central European specimens. Specimens from southwestern and southeastern Europe correspond to central and east European specimens in all five characters.

Characters i) and ii) appear to be taxonomically superior compared to characters iii) – v) as the length and colour of the body pilosity is expected to more strongly vary depending on altitude, geographic latitude or climatic conditions. In fact, the body pilosity of many aculeate hymenopteran species is well known to become more reddish towards the south. Thus, pending future genetic studies, O. tunensis and O. aurulenta are tentatively treated here as different species with the former restricted to northern Africa and the latter occurring in Europe and western Asia. Specimens from Sicily and Malta are considered to belong to O. aurulenta as the differences with mainland European specimens only concern the length and colour of the body pilosity.

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