In the 80 years that have passed since the first issue of Antonie van Leeuwenhoek was published, the field of prokaryote systematics has changed dramatically. The 4th edition of Bergey's Manual of Determinative Bacteriology (1934) described 132 genera and 2,703 species. The numbers of genera and species with names with standing in the nomenclature in August 2013 were 2,390 and 11,482, respectively, including no more than 75 genera and 250 species that were recognized in 1934. In the years 2006-2012, on average 624 new species were added annually, most of which were described by scientists in Asian countries. We review the past and current species concept for the prokaryotes and the current requirements for the description of new species, based on a 'polyphasic' approach. We discuss the impact of genomics and metagenomics and other new trends toward revitalization of prokaryote systematics, and provide some ideas and speculations on possible future developments in the field.