Taxonomy and phylogeny of new wood- and soil-inhabiting Sporothrix species in the Ophiostoma stenoceras-Sporothrix schenckii complex

Abstract

Sporothrix, one of the anamorph genera of Ophiostoma, includes the important human pathogen S. schenckii and various fungi associated with insects and sap stain of wood. A survey of fungi from wood utility poles in South Africa yielded two distinct groups of Sporothrix isolates from different geographical areas. DNA sequence and morphological data derived in this study showed that isolates in these groups represent two novel species in the S. schenckii-O. stenoceras species complex. A new species isolated from pine poles and rosebush wood and phylogenetically closely related to S. pallida is described here as Sporothrix stylites. Phylogenetic analyses also confirmed the synonymy of S. albicans and S. nivea with S. pallida. Sporothrix stylites and S. pallida also are related closely to the isolates from soil, previously treated as “environmental” isolates of S. schenckii. Soil isolates are clearly distinct from human isolates of S. schenckii. We describe the former here as Sporothrix humicola. The isolates from eucalypt poles group peripheral to most other species in the S. schenckii-O. stenoceras complex and are newly described as Sporothrix lignivora. Phylogenetic analyses of sequences of isolates from soil and wood together with those of clinical isolates showed that the human-pathogenic strains form an aggregate of several cryptic species.

• human pathogen
• Ophiostomatales
• sporotrichosis

We thank Meriem el Abdallaoui, Kasper Luijsterburg and Bert Gerrits-van den Ende (CBS) for providing sequence data. Chris van der Merwe and Allan Hall of the laboratory for microscopy and microanalysis at the University of Pretoria are thanked for assistance with electron microscopy. Vishnu Chaturvedi is thanked for providing a complete list of the Sporothrix isolates available at the Wadsworth Center, Albany, New York. We further acknowledge Eskom, the National Research Foundation (NRF), Tree Protection Co-operative Programme (TPCP), the THRIP initiative of the Department of Trade and Industry (DTI) for financial assistance that made this study possible.