AN EXTRAORDINARY NEW BEE AND ADAPTATION OF PALPI FOR NECTAR‐FEEDING IN SOME AUSTRALIAN COLLETIDAE AND PERGIDAE (HYMENOPTERA)

Euryglossa ( Euhesma ) tubulitera sp. n. is remarkable for its enormously enlarged maxillary palpi, which cohere to form a slender tube up to 80% as long as the head and body. The tube functions as a drinking straw, enabling the bees to extract nectar from the essentially bird‐adapted flowers of Calothamnus. Gross enlargement of either the labial or maxillary palpi (but without the formation of a tube) occurs in several groups of Colletidae (Paracolletini, Euryglossinae and Hylaeinae), and must have arisen independently at least 5 times. Most of these bees are associated with flowers of Eremophila. A tube formed from the maxillary palpi is also noted in some Eremophila ‐visiting sawflies (Pergidae). It is postulated that in the Colletidae natural selection has favoured elongation of the palpi (and not the tongue as in higher bees) as an adaptation to flowers with deep‐seated nectaries, because the short tongue plays an important rǒle in nest construction.