Morphology of oil-collecting pilosity of female Rediviva bees (Hymenoptera: Apoidea: Melittidae) reflects host plant use

Abstract

The oil-collecting hair morphology and pilosity on female foretarsi for all 26 species of the southern African endemic bee genus Rediviva was studied and related to host plant use based on about 2700 flower visitation records. Four different types of tarsal pilosity and six principal hair types are identified. Rediviva bees collect floral oil from 12 plant genera representing the families Iridaceae, Orchidaceae, Scrophulariaceae and Stilbaceae, with Diascia being the most frequently used host. Differences in foretarsal pilosity reflect the availability of floral oil and elaiophore morphology of the principal host flowers. Rediviva species with short female forelegs exhibit a greater diversity of tarsal oil-collecting pilosity than long-legged species. This contradicts an earlier hypothesis that the pilosity of species with shorter legs might be less complex than in Rediviva with elongate forelegs.

Keywords:

• Rediviva
• solitary bee
• foretarsal pilosity
• oil-collecting
• flower relationships

Acknowledgements

We are grateful to S. van Noort and D. Larsen, South African Museum, Cape Town, for access to their database of Rediviva flower visitation records and for loan of specimens for studying foretarsal pilosity. Laurence Livermore, London, kindly made linguistic corrections to the manuscript.