africanum" was first described as a subspecies within the MTBC, with phenotypic characteristics intermediate between "M. tuberculosis" and "M. bovis", based on biochemical testing by Castets in 1968.Early genetic analysis showed that it was distinct from "M. tuberculosis" due to a genomic RD9 deletion and distinct "GyrB" nucleotide sequence, and distinct from M. bovis due to an intact RD12 and RD4.