Insect pollination in basal angiosperms is assumed to mostly involve ‘generalized’ insects looking for food, but direct observation of ANITA grade (283 species) pollinators are sparse. We present new data for numerous Schisandraceae, the largest ANITA family, from field work, nocturnal filming, electron microscopy, barcoding, and molecular clocks to infer pollinator/plant interactions over multiple years at sites throughout China to test the extent of pollinator specificity. Schisandraceae are pollinated by nocturnal gall midges that lay eggs in the flowers and whose larvae then feed on floral exudates. At least three Schisandraceae have shifted to beetle pollination. Pollination by a single midge species predominates, but one species was pollinated by different species at three locations and one by two at the same location. Based on molecular clocks, gall midges and Schisandraceae may have interacted since at least the Early Miocene. Combining these data with a review of all published ANITA pollination data shows that ovipositing flies are the most common pollinators of living representatives of the ANITA grade. Compared to food reward-based pollination, oviposition-based systems are less wasteful of plant gametes because (i) none are eaten and (ii) female insects with herbivorous larvae reliably visit conspecific flowers.

Luo_PRSB_Movie1_Kadsura_heteroclita_male_fl_Pinganshan_2015Video S1. Resseliella midges visiting and ovipositing in a male flower of Kadsura heteroclita filmed by the first author in 2015 in Pinganshan, Forest Park, Guangdong, China.Luo_PRSB_Movie2_Kadsura_oblongifolia_female_fl_Danzhou_Hainan_2016Video S2. Resseliella midges visiting and ovipositing in a female flower of Kadsura oblongifolia filmed by the first author in 2016 in Danzhou, Hainan, China.Luo_PRSB_Movie3_Schisandra_spec_Wang_193_male_fl_Hengshan_2015Video S3. Resseliella midges visiting and ovipositing in a male flower of Schisandra spec._Wang_Z.W. 193 filmed by the first author in 2015 in Hengshan, Hunan, China.Luo_PRSB_Movie4_Kadsura_longipedunculata_male_fl_Hengshan_1_2017Video S4. Resseliella midges visiting and ovipositing in Kadsura longipedunculata, filmed by the first author in 2017 in Hengshan, Hunan, China.