The theraphosine genus Hemirrhagus Simon 1903 is revised based on the examination of the type specimens and additional material collected in Mexico. Eight species were redescribed and illustrated. The males of Hemirrhagus ocellatus, Hemirrhagus papalotl, and Hemirrhagus stygius, formerly unknown, are described for the first time. Five new species were recognized and are newly described and illustrated. Hence, Hemirrhagus comprises 21 valid species, all endemic to Mexico. All species are keyed and mapped. New taxonomic features are included in the descriptions and different types of stridulatory organs are described for the first time for the genus. It is reported for the first time that Hemirrhagus is the only known Theraphosinae that lays fixed egg-sacs. Hemirrhagus embolulatus sp. nov. is described as the only known Hemirrhagus that possesses embolus keels present in other Theraphosinae genera. Information on species habitat and reproduction are included. © 2014 The Linnean Society of London

Zoological Journal of the Linnean Society, 170: 634–689