Abstract:
Jacaranda mimosifolia trees have been progressively dying due to Ganoderma root and butt rot
disease in Pretoria (the “City of Jacarandas”) for many years. Ganoderma austroafricanum was described
from these trees previously but this was based on a single collection. This study treats a substantially
expanded collection of isolates of Ganoderma made from all dying trees where basidiomes were present
in a Pretoria suburb. DNA sequences were obtained from the ITS and LSU region for the isolates and
compared against sequences on GenBank. Phylogenetic analyses were used to compare sequences with
those for other Ganoderma species. Based on sequence comparisons and morphological characters,
two new Ganoderma species were discovered and these are described here as G. enigmaticum and
G. destructans spp. nov. Interestingly, the previously described G. austroafricanum was not found, G.
enigmaticum was found on only one Ceratonia siliqua tree and G. destructans was found on all other
trees sampled. The latter species appears to be the primary cause of root rot of J. mimosifolia in the area
sampled.
