Multi-gene phylogenies and phenotypic characters distinguish two species
within the Colletogloeopsis zuluensis complex associated with
Eucalyptus stem cankers
Colletogloeopsis zuluensis, previously known as Coniothyrium
zuluense, causes a serious stem canker disease on Eucalyptus
spp. grown as non-natives in many tropical and sub-tropical countries. This
stem canker disease was first reported from South Africa and it has
subsequently been found on various species and hybrids of Eucalyptus
in other African countries as well as in countries of South America and
South-East Asia. In previous studies, phylogenetic analyses based on DNA
sequence data of the ITS region suggested that all material of C.
zuluensis was monophyletic. However, the occurrence of the fungus in a
greater number of countries, and analyses of DNA sequences with additional
isolates has challenged the notion that a single species is involved with
Coniothyrium canker. The aim of this study was to consider the phylogenetic
relationships amongst C. zuluensis isolates from all available
locations and to support these analyses with phenotypic and morphological
comparisons. Individual and combined phylogenies were constructed using DNA
sequences from the ITS region, exons 3 through 6 of the β-tubulin gene,
the intron of the translation elongation factor 1-α gene, and a partial
sequence of the mitochondrial ATPase 6 gene. Both phylogenetic data and
morphological characteristics showed clearly that isolates of C.
zuluensis represent at least two taxa. One of these is C.
zuluensis as it was originally described from South Africa, and we
provide an epitype for it. The second species occurs in Argentina and Uruguay,
and is newly described as C. gauchensis. Both fungi are serious
pathogens resulting in identical symptoms. Recognising them as different
species has important quarantine consequences