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.

中文翻译：

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Microthia、Holocryphia 和 Ursicollum，桉树和 Coccoloba 上的三个新属，用于真菌以前称为 Cryphonectria。

Cryphonectria havanensis 是一种与古巴和佛罗里达（美国）的桉树物种有关的真菌。直到最近，C. havanensis 还没有活的文化，因此无法评估其分类地位。然而，从墨西哥和夏威夷（美国）的桉树调查中发现了被认为代表这种真菌的分离株。这项研究的结果表明，这些分离物代表 C. havanensis，但属于不同于 Cryphonectria sensu stricto 的属，这里将其描述为 Microthia。发生在亚速尔群岛和马德拉岛杨梅上的一种不明真菌的分离株也归入 Microthia，与其他 M. havanensis 分离株相同。Cryphonectria coccolobae，一种发生在百慕大和佛罗里达州海葡萄（Coccoloba uvifera）上的真菌，被发现在形态上与 Microthia 相同，并被转移到该属，但作为一个不同的物种。在佛罗里达州对海葡萄上的 M. coccolobae 进行的调查从该宿主中产生了第二种 diaporthalean 真菌。这种真菌在形态和系统发育上不同于 M. coccolobae 和其他密切相关的分类群，被描述为 Ursicollum fallax gen。等 sp. 十一月 本研究中的系统发育分析还表明，C. eucalypti（南非和澳大利亚桉树的病原体）的分离株属于一个独立于所有其他组的进化枝，包括代表 Cryphonectria sensu stricto 的进化枝。Cryphonectria eucalypti 具有与所有其他 Cryphonectria 物种不同的子囊孢子分隔这一事实支持这种差异。因此，为 C. eucalypti 建立了一个新属 Holocryphia。