A new species of <i>Entyloma</i> (Entylomatales, Exobasidiomycetes) on the ornamental plant <i>Eryngium planum</i> expands the <i>En. eryngii</i> species complex

The plant genus <i>Eryngium</i> (Apiaceae) includes various species used as condiments, ornamentals in gardens, or as elements in floral arrangements. In recent years, there has been a surge in interceptions from South America at U.S. ports of entry, leading to the subsequent destruction of these plants due to the presence of an unidentified species of <i>Entyloma</i> (Entylomatales, Exobasidiomycetes). The combination of morphology, host, and geographic origin did not align with any reported species on <i>Eryngium</i>. This study aimed to identify and characterize this unknown <i>Entyloma</i> sp. ascertain its phylogenetic relationship with other <i>Entyloma</i> species, and verify the identity of the host plant. Morphological and phylogenetic (nuc rDNA internal transcribed spacer [ITS] regions) analyses were performed, in context with available sequences and species of <i>Entyloma</i>. Nuc rDNA ITS was also used to attempt the identification of the host. Findings reveal that the unidentified <i>Entyloma</i> sp. forms a distinct and well-supported clade separate from other species on <i>Eryngium</i>. Its closest relatives include <i>En. carmeli, En. eryngii, En. eryngii-cretici, En. eryngii-plani, En. lagoeciae</i>, and <i>En. scandicis</i>. Morphologically, it resembles <i>En. argentinense, En. eryngii-alpini, En. eryngii-cretici, En. eryngii-maritimi</i>, and <i>En. eryngii-plani</i>; however, a combination of host affiliation, geography, and morphology distinguishes the new <i>Entyloma</i> sp. from these five species. Therefore, the new species <i>Entyloma meridionale</i> is described herein. The host plant was confirmed as <i>Eryngium planum</i>. This research increases knowledge of <i>Entyloma</i> diversity and contributes to understanding the dynamics of pathogen movement and potential invasion into new territories.刺芹属（<i>Eryngium</i>，伞形科（Apiaceae））包含多个可作为调味品、园林观赏植物或切花配材的物种。近年来，美国入境口岸从南美地区截获的刺芹属植物数量大幅增加，由于这些植株感染了未鉴定的白锈菌属（<i>Entyloma</i>，白锈菌目（Entylomatales），外担菌纲（Exobasidiomycetes））物种，截获材料随后均被销毁。结合形态学特征、寄主信息与地理起源，该病原菌无法匹配任何已报道的寄生于刺芹属的白锈菌物种。本研究旨在鉴定并表征这一未知<i>Entyloma</i>菌种，明确其与其他白锈菌物种的系统发育关系，并验证寄主植物的身份。研究结合已公开的白锈菌物种序列数据，开展了形态学与系统发育分析（针对核核糖体DNA内部转录间隔区（nuc rDNA ITS）），同时利用核rDNA ITS序列尝试鉴定寄主植物。结果显示，该未知白锈菌菌种形成了一个独立且支持度良好的演化支，与其他寄生于刺芹属的白锈菌物种相区分。其近缘物种包括<i>En. carmeli</i>、<i>En. eryngii</i>、<i>En. eryngii-cretici</i>、<i>En. eryngii-plani</i>、<i>En. lagoeciae</i>以及<i>En. scandicis</i>。形态上，该菌种与<i>En. argentinense</i>、<i>En. eryngii-alpini</i>、<i>En. eryngii-cretici</i>、<i>En. eryngii-maritimi</i>及<i>En. eryngii-plani</i>相似，但结合寄主亲和性、地理分布与形态特征，可将这一新的白锈菌菌种与上述五个物种区分开来。因此，本文正式描述一新种：南方白锈菌（<i>Entyloma meridionale</i>）。寄主植物经鉴定为扁叶刺芹（<i>Eryngium planum</i>）。本研究丰富了对白锈菌属多样性的认知，有助于理解病原菌传播动态及其入侵新领地的潜在风险。