One of the best ways of finding new species is to sequence the genes of existing ones. Often, scientists discover genetically distinct populations that count as species in their own right, hiding in plain sight. So, the African elephant turns out to be two genetically distinct groups of African elephants. A skipper butterfly  is actually ten skipper butterflies. There are two Nile crocodiles, and possibly four killer whales. Time and again, scientists have peered at a creature’s DNA and discovered that one species is actually two, or three, or a dozen.

Or perhaps hundreds.

Until ten years ago, scientists talked about the lichen Dictyonema glabratum as if it were a single species. Its large, conspicuous, and elegant fronds