ABSTRACT

Dictyochaeta (Chaetosphaeriaceae) is a phialidic dematiaceous hyphomycete with teleomorphs classified in Chaetosphaeria. It is associated with significant variability of asexual morphological traits, which led to its broad delimitation. In the present study, six loci: nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode), nuc 18S rDNA (18S), nuc 28S rDNA (28S), DNA-directed RNA polymerase II second largest subunit gene (RPB2), translation elongation factor 1-α (TEF1-α), and β-tubulin (TUB2), along with comparative morphological and cultivation studies, are used to reevaluate the concept of Dictyochaeta and establish species boundaries. Based on revised species, morphological characteristics of conidia (shape, septation, absence or presence of setulae), collarettes (shape), and setae (presence or absence) and an extension of the conidiogenous cell proved to be important at the generic level. The dual DNA barcoding using ITS and TEF1-α, together with TUB2, facilitated accurate identification of Dictyochaeta species. Thirteen species are accepted, of which seven are characterized in this study; an identification key is provided. It was revealed that D. fuegiana, the type species, is a complex of three distinct species including D. querna and the newly described D. stratosa. Besides, a new species, D. detriticola, and two new combinations, D. callimorpha and D. montana, are proposed. An epitype of D. montana is selected. Dictyochaeta includes saprobes on decaying wood, bark, woody fruits, and fallen leaves. Dictyochaeta is shown to be distantly related to the morphologically similar Codinaea, which is resolved as paraphyletic. Chaetosphaeria talbotii with a Dictyochaeta anamorph represents a novel lineage in the Chaetosphaeriaceae; it is segregated from Dictyochaeta, and a new genus Achrochaeta is proposed. Multigene phylogenetic analysis revealed that D. cylindrospora belongs to the Vermiculariopsiellales, and a new genus Tubulicolla is introduced.

摘要

Dictyochaeta (Chaetosphaeriaceae) 是一种有丝状体的暗色丝状菌纲，具有分类在Chaetosphaeria 中。它与无性形态特征的显着变异有关，这导致了其广泛的界定。在本研究中，6个基因座：nuc rDNA内部转录间隔区ITS1-5.8S-ITS2（ITS条码）、nuc 18S rDNA（18S）、nuc 28S rDNA（28S）、DNA导向的RNA聚合酶II第二大亚基基因（RPB2 )、翻译延伸因子 1-α ( TEF1-α ) 和 β-微管蛋白 ( TUB2 ) 以及比较形态学和培养研究，用于重新评估网纹藻的概念并建立物种界限。根据修改后的物种，分生孢子的形态特征（形状、分隔、小刚毛的缺失或存在）、领状（形状）和刚毛（存在或缺失）以及分生孢子细胞的延伸被证明在通用水平上很重要。使用 ITS 和TEF1-α以及TUB2的双 DNA 条形码促进了双链菌属物种的准确识别。接受了 13 个物种，其中 7 个在本研究中被表征；提供识别密钥。研究表明，模式种D. fuegiana是三个不同物种的复合体，包括D. querna和新描述的D. stratosa. 此外，还提出了一个新种D. detriticola和两个新组合D. callimorpha和D. montana。选择了D. montana的表型。Dictyochaeta包括腐烂的木材、树皮、木质果实和落叶上的腐烂物。Dictyochaeta被证明与形态相似的Codinaea有远亲关系，后者被解析为并系群。Chaetosphaeria talbotii与Dictyochaeta anamorph 代表了 Chaetosphaeriaceae 的一个新谱系；它是从网毛纲中分离出来的一个新属Achrochaeta被提议。多基因系统发育分析表明，D. cylindrospora属于Vermiculariopsiellales，并引入了新的Tubulicola属。