Abstract
Some bees and pollen wasps have independently evolved simple, stiff, erect, apically-curved, curly or hooked facial setae as adaptations to collect pollen from nototribic flowers. A distinctive new species of
Chalicodoma
Lepeletier de Saint Fargeau subgenus
Pseudomegachile
Friese from Saudi Arabia with such morphological adaptations,
Chalicodoma riyadhense
sp. n.
, is described and figured. The species was captured visiting flowers of
Blepharis ciliaris
(L.) (
Acanthaceae
). The occurrence of modified facial setae is documented and discussed for the first time in eight other species of
Pseudomegachile
, and a key to the genera and subgenera of
Megachilini
currently confirmed for Saudi Arabia is provided.