Observations on Texas hypoxylons, including two new <i>Hypoxylon</i> species and widespread environmental isolates of the <i>H. croceum</i> complex identified by a polyphasic approach
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Two new species and a new combination of <i>Hypoxylon</i> from Texas were identified and described based on morphological, multigene phylogenetic (ITS [nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2], 28S [5′ 1200 bp of nuc 28S rDNA], <i>RPB2</i> [partial second largest subunit of the DNA-directed RNA polymerase II], <i>TUB2</i> [partial β-tubulin<b>]</b>), and chemotaxonomic data. <i>Hypoxylon olivaceopigmentum</i> is characterized by its pulvinate to glomerate stromata, olivaceous KOH-extractable pigments, equilateral ascospores, and indehiscent perispore. <i>Hypoxylon texense</i> can be distinguished from morphologically similar species by its rust to dark brick KOH-extractable pigments and the high-performance liquid chromatography (HPLC) profile of its stromatal secondary metabolites. <i>Hypoxylon hinnuleum</i> is proposed as the sexual morph of <i>Nodulisporium hinnuleum</i>, featuring dark vinaceous glomerate stromata with dark brick KOH-extractable pigments composed of cohaerin-type azaphilones and smooth equilateral ascospores with indehiscent perispore. Based on these diagnostic characters, <i>H. hinnuleum</i> forms a complex with <i>H. croceum</i> and <i>H. minicroceum</i>. More than 50 ITS sequences with high identity originating from North American and East Asian environmental isolates formed a well-supported clade with the type of <i>N. hinnuleum</i>, demonstrating the widespread distribution of the species complex. In addition, updated descriptions and comprehensive illustrations with detailed information on the diagnostic features of <i>H. fendleri</i> and <i>H. perforatum</i> are provided. The multilocus phylogenetic reconstruction of <i>Hypoxylon</i> supported the status of the new species and broadened the knowledge about intergeneric relationships.
本研究基于形态学、多基因系统发育（涵盖核核糖体DNA内转录间隔区[ITS, nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2]、核核糖体28S rDNA 5'端1200 bp序列[28S]、DNA指导的RNA聚合酶II第二大亚基部分序列[*RPB2*]以及β-微管蛋白部分序列[*TUB2*]）与化学分类学数据，对得克萨斯州发现的2个炭团菌属（*Hypoxylon*）新种及1个新组合分类单元开展了鉴定与描述。*Hypoxylon olivaceopigmentum*（橄榄色素炭团菌）以其垫状至聚生的子座、KOH提取液呈橄榄色的色素、等侧生子囊孢子以及不开裂的孢子周壁为典型鉴别特征。*Hypoxylon texense*（德克萨斯炭团菌）可通过其KOH提取液呈锈色至深砖红色的色素，以及子座次生代谢物的高效液相色谱（high-performance liquid chromatography, HPLC）特征与形态学近似物种相区分。本研究将*Hypoxylon hinnuleum*处理为*Nodulisporium hinnuleum*的有性态，该物种具有暗酒红色聚生子座，其KOH提取色素由柯林型氮杂菲酮类化合物构成且呈深砖红色，同时拥有具不开裂孢子周壁的光滑等侧生子囊孢子。基于上述分类诊断特征，*H. hinnuleum*与*H. croceum*（橙黄炭团菌）和*H. minicroceum*（微橙炭团菌）共同构成一个复合类群。超过50条源自北美与东亚环境分离物的高同源性ITS序列，与*N. hinnuleum*的模式菌株形成了一支高支持率的演化支，证实该复合类群具有广泛的分布范围。此外，本研究还提供了*H. fendleri*（芬德勒炭团菌）与*H. perforatum*（穿孔炭团菌）的更新描述，以及包含详细分类诊断特征信息的综合图解。炭团菌属的多位点系统发育重建结果，不仅支持了上述新种的分类地位，同时拓宽了学界对该属属间亲缘关系的认知。
