Basidiocarps of Pisolithus associated with indigenous
(Afzelia quanzensis Welw.) and introduced (Pinus caribaea
Mor. and Eucalyptus camaldulensis Dehnh.) hosts in the
lowland forests of the Coast Province of Kenya are
morphologically distinct. Genetic variability among 52 Pisolithus
basidiocarps, collected beneath the various host
plants, was examined based on sequence polymorphism within the
internal transcribed spacer (ITS) and
intergenic spacer (IGS1) of ribosomal DNA genes. Variability in ITS and
IGS1 sequences indicated that the three
host-associated morphotypes were genetically different. Consensus
trees generated by bootstrap analysis of
sequence data of Pisolithus isolates from Australia and Kenya
are polyphyletic and strongly suggest that the three
different morphotypes/genotypes present in Kenya represent separate
biological species. In addition, our data
indicate that little genetic exchange occurs in silva between
these species.