SIBLING SPECIES WITHIN OPHIOSTOMA-PICEAE

Fifty-five hardwood or conifer derived isolates of the heterothallic fungus Ophiostoma piceae from Europe and North America were separated into two inter-sterile mating groups. One group, designated OPH, came almost exclusively from hardwood hosts while the other isolates, designated OPC, came predominantly (75%) from conifers. The A and B sexual compatibility types occurred within both groups, though seven OPH isolates from North America were all B types. The OPH and OPC forms of O. piceae are considered here to be distinct, reproductively isolated sibling species. The OPH group may equate to O. querci and the OPC group to O. piceae. Each sibling species occurs in both Europe and North America. Their possible evolutionary origins are discussed.