If you stop to think about it, purple is one of the least common colors in all of nature, even here in the Tambopata rainforests.
Thus, when I come across anything purple, from a leaf to a beetle, I always take the time to try and get a good shot.
One of the more pleasing-to-the-eye beetles around the Tambopata rainforests is this here Gibbifer sp., a pleasing fungus beetle. I’ve seen them range from light sky blue, to dark blue, to this purple, and I’m unsure if they make up one species or several.
A purple pleasing fungus beetle,Gibbifersp. - Phil Torres
Pleasing Fungus Beetles are beetles in the family Erotylidae and feed exclusively on basidiomycete fungus (aka shelf-mushroom looking fungus) as both larvae and adult, with specific host species they feed on. If you find a dry fallen tree with some fungus growing on it, you almost always will find one of these beetles shuffling around. Their bright colors make them quite conspicuous so they likely have some form of chemical defense.
So why are the colors purple and blue so rare in animals? Scientists actually aren't exactly sure. It likely has to do with the complexity and rarity of molecules that create the color blue/purple color, as well as the fact that those pigments that form blue/purple are found more in high saline alkaline environments. These alkaline environments are difficult for most organisms to thrive in, thus the low numbers of animals that actually can be blue/purple.
This could be why we see a lot of blue/purple color formed from a structural scattering of light (much like a blue morpho) rather than an actual pigment, because scattering is a bit 'easier' to evolve.
As for the beetles, I have no idea why they are called pleasing fungus beetles, perhaps because they really are pleasing to look at or their notably docile ‘personality.’ There is also another family, the Endomychidae, which are commonly called the ‘handsome fungus beetles.’ I think someone was fond of fungus beetles.
For a great review and key to genera of the family Erotylidae, see here.
And for the final test, say “purple pleasing fungus beetle” five times fast.
To see more posts by biologist Phil Torres, check out TheRevScience.com