Neighbour-joining similarity tree for 16S rRNA gene sequences of most mycobacterial species. Legend: N. asteroides ATCC 49872 (Genbank Z82229) was used as the outgroup. Table 1 lists the GenBank accession numbers of the sequences used to construct this tree. ARDRA patterns for Hha I, Mbo I, Rsa I and Bst UI are listed after the species name. a: GenBank AF028712. Erroneously listed in GenBank as M. peregrinum (see also legend of Table 1). b: M. gastri clusters below 100% with M. kansasii, although it is generally agreed that the 16S rRNA gene sequences for M. kansasii and M. gastri are identical. This can be explained by the fact that the only available GenBank M. gastri sequence (X52919) contained several ambiguities. c. M. lentiflavum, initially not included in the manuscript is not presented in this tree. It clusters close to the branch including M. heidelbergense, M. simiae, M. triplex and M. genavense.