All representatives of the aleocharine subtribe Gyrophaenina feed on spore of macro-fungi, the mushrooms that we’re mostly familiar with. And in order, I guess, to neatly fit in between the gills of a mushroom (where the spores are produced), most gyrophaenines have flattened bodies.
Some genera, to the contrary, are collected by sifting various debris where the beetles are thought, by me, to feed on mold spores. This is because those mouthpart characters that have been attributed to be adaptive to gathering spores in mushroom gyrophaenines are also present in litter-inhabiting gyrophaenines.
Meet Encephalus americanus, the only species of the genus in North America.
Only three other species are described in the genus, E. complicans in Europe, E. laetulus and E. zealandicus from New Zealand. It appears that E. complicans and E. americanus are associated with bog-margin litter, which is correlated with their northern distributions. Interestingly, these litter-inhabiting gyrophaenines are not flattened but compact and stumpy looking. Maybe when they are threatened they curl up and fall through the matrix of litter-substrate?