‘Shout hurrah!’ New thoughts on the origin and meaning of the bat species name Ia io, created in 1902 by Oldfield Thomas FRS

In 1902, British naturalist Oldfield Thomas discovered a new species of bat in a collection of specimens sent to him from China. He named the new species Ia io, thereby creating a species name that is four letters in length—the shortest possible name allowed under the rules for naming a new species. In the time since, biologists have wondered why he chose this unusual name and what the name might mean in translation. The most widespread theory on the short name is that he was challenged by an American colleague to deliberately create the shortest species name possible. The question of what the name might mean in translation is more problematic. ‘Ia’ has been thought by most taxonomists to be a meaningless word, but ‘io’ has been suggested to refer to a mythological Greek priestess named Io. Herein, I show that the species name Ia io translates into ‘Shout hurrah!’ and demonstrate that the events in Oldfield Thomas's early professional life gave him an excellent reason for choosing this unusual species name in 1902.