Mimicking Livor Mortis: a Well-Known but Unsubstantiated Color Profile in Sapromyiophily.

By emitting strong scents resembling rotting organic materials suitable for oviposition and/or foraging of flies, sapromyiophilous flowers mimic the substrates that attract flies as pollinators. It has been suggested that the wide range of volatile organic compounds emitted by this deceptive pollination system reflects the trophic preferences of flies to different types of substrate, including herbivore and carnivore feces, carrion, and fruiting bodies of fungi. Previous studies suggest that floral scents play a particularly important role in sapromyiophily. However, few studies on the relative importance of floral color or synergy between visual and olfactory cues in sapromyiophily have been substantiated. In this study, we analyzed fetid floral odor, floral pigment composition, and reflectance of an Amorphophallus konjac C. Koch inflorescence, and we conducted bioassays with different visual and/or olfactory cues to explore an unsubstantiated color profile in sapromyiophily: mimicking livor mortis. Our analysis showed A. konjac can emit oligosulphide-dominated volatile blends similar to those emitted by carrion. Necrophagous flies cannot discriminate between the color of an inflorescence, livor mortis, and floral pigments. We concluded that mimicking livor mortis may represent a common tactic of pollinator attraction in "carrion flower" systems within angiosperms.