Narrow flower specialization in two European bee species of the genus Colletes (Hymenoptera: Apoidea: Colletidae)

Abstract

Colletes anchusae Noskiewicz, 1924 and C. wolfi Kuhlmann, 1999 (Colletidae) are closely related bee species with vicariant distributions, the former occurring in east and southeast Europe and Turkey, the latter restricted to the Italian peninsula. Microscopical analysis of scopal pollen revealed that in Europe both species are monolectic collecting pollen exclusively from flowers of Cynoglottis barrelieri (All.) Vural and Kit Tan (Boraginaceae). In Turkey, C. anchusae possibly visits also Cynoglottis chetikiana Vural and Kit Tan. The distributions of the two bee species and of Cynoglottis coincide. The females of both Colletes species are equipped with stout, curved bristles on their foretarsi used for scraping pollen out of the narrow flower tube of Cynoglottis. Compared to other European species of Colletes the foretarsi of C. anchusae and C. wolfi are shortened, presumably an adaptation to the short corolla tube of their host plant.