A morphological and molecular analysis was performed on 25 individuals
of Phaeoacremonium isolated from diseased European and
Californian grapevines (Esca disease). An unexpectedly high intra-generic
molecular divergence was evidenced by partial rDNA
sequencing between P. chlamydosporum isolates on one hand and
an aggregate including P. angustius and P. aleophilum
isolates and
some undescribed ones on the other. These two groups show 26% nucleotide
differences within the 26S rDNA fragment sequenced
and were unalignable within the ITS2, suggesting distant phylogenetic relationships.
Moreover, P. chlamydosporum appeared more
closely related to Phialophora verrucosa (supposed to be an
anamorph of the Herpotrichiellacae), than to the type species of the
genus, P. parasiticum (more related to Magnaporthaceae).