Taxonomic Notes on Mexican Bats of the Genus Rhogeëssa

E. Raymond Hall's 1952 taxonomic revision tackles one of mammalogy's thornier problems: making sense of bats in the genus Rhogeëssa that blur the lines between species. Hall examines specimens collected across Mexico, from the deserts of Sonora to the Gulf coast of Veracruz, comparing their skulls, teeth, and measurements against existing museum collections. His argument is precise and careful: what scientists have called three distinct species, Rhogeëssa parvula, Rhogeëssa tumida, and Rhogeëssa gracilis, may in fact represent geographic variations of a single, wider-ranging species. This was controversial work that challenged established names, and Hall knew it. He writes not with swagger but with the confidence of someone who has done the painstaking labor, measuring bone after bone, comparing location after location. For mammalogists and anyone wrestling with how to define a species, this paper remains a masterclass in taxonomic reasoning.