Cytospora species are destructive canker and dieback pathogens of woody hosts in natural and agroecosystems around the world. In this genus, molecular identification has been limited due to the paucity of multi-locus sequence typing studies and the lack of sequence data from type specimens in public repositories, stalling robust phylogenetic reconstructions. In most cases a morphological species concept could not be applied due to the plasticity of characters and significant overlap of morphological features such as spore dimensions and fruiting body characters. In this study, we employed a molecular phylogenetic framework with the inclusion of four nuclear loci (ITS, translation elongation factor 1-alpha, actin, and beta-tubulin) to unveil the biodiversity and taxonomy of this understudied important genus of plant pathogens. Phylogenetic inferences based on 150 Californian isolates revealed 15 Cytospora species associated with branch and twig cankers and dieback of almond, apricot, cherry, cottonwood, olive, peach, pistachio, plum, pomegranate, and walnut trees in California. Of the 15 species recovered in this study, 10 are newly described and typified, in addition to one new combination. The pathogenic status of the newly described Cytospora species requires further investigation as most species were associated with severe dieback and decline of diverse and economically important fruit and nut crops in California.

中文翻译：

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与加州水果和坚果作物溃疡病相关的细胞孢子菌物种的分子系统发育，包括十个新物种和一个新组合的描述。

细胞孢子菌属是世界各地自然和农业生态系统中木本宿主的破坏性溃疡病和枯死病原体。在该属中，由于缺乏多位点序列分型研究以及公共存储库中模式标本的序列数据的缺乏，分子鉴定受到限制，阻碍了稳健的系统发育重建。在大多数情况下，由于性状的可塑性和形态特征（例如孢子尺寸和子实体特征）的显着重叠，形态物种概念无法应用。在这项研究中，我们采用了包含四个核位点（ITS、翻译延伸因子 1-α、肌动蛋白和 β-微管蛋白）的分子系统发育框架来揭示这一正在研究的重要植物病原体属的生物多样性和分类学。基于 150 个加州分离株的系统发育推断揭示了 15 种细胞孢子菌物种与加州杏仁、杏、樱桃、三叶杨、橄榄、桃、开心果、李子、石榴和核桃树的枝条溃疡病和枯死病相关。在本研究中发现的 15 个物种中，除了 1 个新组合外，还有 10 个物种被新描述和典型化。新描述的细胞孢子菌属物种的致病状况需要进一步调查，因为大多数物种与加利福尼亚州多种重要经济水果和坚果作物的严重顶枯和衰退有关。