Syrphid fly pollination of Guihaiothamnus acaulis (Rubiaceae), a species with "butterfly" flowers
Pei-Wu XIE,Zhong-Lai LUO,Dian-Xiang ZHANG
J Syst Evol . 2013, (1): 86 -93 .  DOI: 10.1111/j.1759-6831.2012.00191.x