STUDIES IN MYCOLOGY 50: 119–142. 2004. 119 Chrysoporthe, a new genus to accommodate Cryphonectria cubensis

Abstract: Cryphonectria cubensis is an important canker pathogen of tree species residing in the Myrtaceae and Melas-tomataceae. Recent phylogenetic studies based on multiple gene sequence comparisons have revealed that isolates of C. cubensis group separately from other Cryphonectria species. Within the C. cubensis clade, isolates formed three distinct sub-clades that include isolates mainly from South America, South Africa and South East Asia, respectively. In this study, we establish a new genus, Chrysoporthe, for this species. Chrysoporthe is characterized by superficial, blackened conidiomata, limited ascostromatic tissue, and blackened perithecial necks protruding from the orange stromatal surface. Although speci-mens of C. cubensis from South East Asia and South America reside in two distinct phylogenetic sub-clades, they could not be separated or distinguished from the type specimen, originating from Cuba, based on morphological characteristics. For the present, these specimens are collectively transferred to Chrysoporthe as a single species, Chrysoporthe cubensis. Specimens previously treated as C. cubensis from South Africa reside in a discrete phylogenetic clade and could be distinguished from those in the other sub-clades based on having longer asci and ascospores with rounded apices as opposed to tapered apices. The South African fungus is described as Chrysoporthe austroafricana. Isolates from Tibouchina spp. in Colombia resided in a fourth sub-clade of Chrysoporthe. Isolates in this phylogenetic assemblage grew optimally at 25 °C in contrast to those in the other groups that grew optimally at 30 °C. No sexual state is known for the fungus in this fourth sub-clade and a ne