Phylogeny of the Ophiostoma stenoceras-Sporothrix schenckii complex

Abstract

Ophiostoma stenoceras is a well-known sapwood-colonizing fungus occurring on some coniferous and hardwood hosts in the Northern Hemisphere. In the Southern Hemisphere, the fungus has been reported only from New Zealand. The human pathogen, Sporothrix schenckii, has been suggested to be the anamorph of O. stenoceras. The aim of this study was to gain a better understanding of the phylogenetic relationship between these two species. The study also provided the opportunity to confirm the identity of some Sporothrix and O. stenoceras-like isolates recently collected from wood and soil around the world. For this purpose, the DNA sequence of internal transcribed spacer (ITS) regions of the ribosomal RNA operon was determined. Isolates of O. nigrocarpum, O. albidum, O. abietinum, O. narcissi and O. ponderosae, all morphologically similar to O. stenoceras, were included in the study. From phylogenetic analyses of the sequence data, four main clades were observed. These represented O. stenoceras, O. nigrocarpum and two separate groups containing isolates of S. schenckii. Our results confirm earlier suggestions that S. schenckii should be classified within the teleomorph genus Ophiostoma but support studies separating O. stenoceras and S. schenckii. Ophiostoma albidum and O. ponderosae should be considered synonyms of O. stenoceras. The status of O. narcissi and O. abietinum needs further clarification. The two groups within S. schenckii might represent two species, but this needs to be confirmed. This study represents the first reports of O. stenoceras from Colombia, Kenya, Uruguay and South Africa.