This second edition has come about because the first edition (2010) is sold out. It has enabled inclusion of many new photos as well as sharpening the details of occurrence of some species and improving many of the existing photos. There have since the first edition been two genera resurrected or newly described by Darrel Plowes, viz. Hutchinia and Pleuralluma. He has also erected or resurrected 22 new species in Angolluma, Ballyanthus, Echidnopsis, Huernia and Orbeopsis, which are included in this second edition. Also included are two new species of Sulcolluma by Tom McCoy and a new species of Huernia by Giuseppe Orlando and Marwan El Azzouni.