Fig. 1
Variation in shape and size of floral callus, mentum, stelidia and corresponding orchid pollinators. a An Hoplitis adunca male bee is pollinating a Serapias cordigera flower in France, its front legs grab the callus on the labellum, while the pollinia are attached to its forehead; b an Andrena sp. male bee receives pollinia on its proboscis while pseudocopulating with a flower of Ophrys splendida in France; c a Drosophila sp. fly is trapped against the anther, while pollinating a flower of Specklinia spectabilis in Costa Rica; d an Amegilla nigritar bee bears a pollinarium on its head while approaching a flower of Phalaenopsis pulcherrima in China. Ca callus, Me mentum, St stelidia. Scale bars: 1 mm. Photographs by Jean Claessens (a, b), Adam Karremans (c) and Jin Xiaohua (d)