The taxonomic validity of morphological group III Acanthamoeba spp. is uncertain. In the present study, six type strains of group III Acanthamoeba spp., Acanthamoeba culbertsoni, A. healyi, A. pustulosa, A. palestinensis, A. royreba and A. lenticulata were subjected for the evaluation of their taxonomic validity by comparison of the isoenzyme patterns by isoelectic focusing on polyacrylamide gels, mitochondrial DNA (Mt DNA) restriction fragment length polymorphism (RFLP), and small subunit ribosomal DNA (ssu rDNA) PCR-RFLP patterns. The Mt DNA RFLP patterns were heterogeneous between species. The type strains of A. palestinensis and A. pustulosa showed almost identical patterns of isoenzymes and rDNA PCR-RFLP with an estimated sequence divergence of 2.6%. The other species showed heterogeneous patterns of isoenzymes and rDNA PCR-RFLP. It is likely that A. pustulosa is closely related with A. palestinensis and that the former may be regarded as a junior synonym of the latter.
