A Synopsis of the American Bats of the Genus Pipistrellus

A concise taxonomic review of North American Pipistrellus bats that evaluates specimens from the United States and Mexico, compares external, skull, and dental traits, and revises species limits: recognizes two valid species, distinguishes an eastern brownish form and a western gray form, reduces veracrucis to a subspecies of the eastern taxon, and transfers cinnamomeus to the genus Myotis. The paper details diagnostic characters (color, foot and thumb proportions, tragus shape, skull profile, incisors and premolar morphology), maps geographic distributions and subspecies, and discusses specimen records and geographic variation across U.S. and Mexican localities.