Cryphonectria havanensis is a fungus associated with Eucalyptus species in Cuba and Florida (U.S.A.). Until recently, there have been no living cultures of C. havanensis and it has thus not been possible to assess its taxonomic status. Isolates thought to represent this fungus have, however, emerged from surveys of Eucalyptus in Mexico and Hawaii (U.S.A.). Results of this study showed that these isolates represent C. havanensis but reside in a genus distinct from Cryphonectria sensu stricto, which is described here as Microthia. Isolates of an unidentified fungus occurring on Myrica faya in the Azores and Madeira also grouped in Microthia and were identical to other M. havanensis isolates. Cryphonectria coccolobae, a fungus occurring on sea grape (Coccoloba uvifera) in Bermuda and Florida, was found to be morphologically identical to Microthia and is transferred to this genus, but as a distinct species. Surveys for M. coccolobae on sea grape in Florida, yielded a second diaporthalean fungus from this host. This fungus is morphologically and phylogenetically distinct from M. coccolobae and other closely related taxa and is described as Ursicollum fallax gen. et sp. nov. Phylogenetic analyses in this study have also shown that isolates of C. eucalypti, a pathogen of Eucalyptus in South Africa and Australia, group in a clade separate from all other groups including that representing Cryphonectria sensu stricto. This difference is supported by the fact that Cryphonectria eucalypti has ascospore septation different to that of all other Cryphonectria species. A new genus, Holocryphia, is thus erected for C. eucalypti.

The newly collected specimens from Co. uvifera in Florida were morphologically different from those representing C. coccolobae. Conidiomata were pyriform to rostrate, often having a globose base with a long to tapered cylindrical neck or more than one neck (Figs 5A–D, 6A–B). This was different from conidiomata of C. coccolobae which are pulvinate without long necks (Fig. 4E–F). Furthermore, necks of the conidiomata were often covered with short hairs (Fig. 5F). Conidial locules of the Florida specimens (Figs 5D, 6B) also did not contain the long, sterile paraphyses commonly found in locules of C. coccolobae (Fig. 4H–J). No teleomorph was observed for the Florida specimens on the bark.