1Medical Technology Program, Department of Microbiology,Michigan State University, East Lansing, Michigan48824-1031
2Instituto L. S. Lima,Bauru, São Paulo, Brazil 17001-970
3Department of Plant and Microbial Biology, University ofCalifornia, Berkeley, California 94720-3102 and
4Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia 30322
Lacazia loboi is the last of the classical fungal pathogens to remain a taxonomic enigma, primarily because it has resistedcultivation and only causes cutaneous and subcutaneous infectionsin humans and dolphins in the New World tropics. To place it inthe evolutionary tree of life, as has been done for the otherenigmatic human pathogens Pneumocystis carinii and Rhinosporidiumseeberi, we amplified its 18S small-subunit ribosomal DNA (SSUrDNA) and 600 bp of its chitin synthase-2 gene. Our phylogeneticanalysis indicated that L. loboi is the sister taxon of the humandimorphic fungal pathogen Paracoccidioides brasiliensis and thatboth species belong with the other dimorphic fungal pathogensin the order Onygenales. The low nucleotide variation among threeP. brasiliensis 18S SSU rDNA sequences contrasts with the surprisingamount of nucleotide differences between the two sequences ofL. loboi used in this study, suggesting that the nucleic acidepidemiology of this hydrophilic pathogen will berewarding.