Mangroves play a significant part in the marine ecosystem and harbour a plethora of microorganisms vital for various ecological functions. However, they remain vulnerable to disruptive impacts caused by fungal plant pathogens. In this study, leaves with anthracnose symptoms were collected from mangrove forests in Prachuap Khiri Khan, Thailand. Three species were identified using a polyphasic approach namely two new species – Colletotrichum avicenniae from Avicennia marina, Colletotrichum lumnitzerae from Lumnitzera racemosa, and a known species Colletotrichum tropicale. Combined analysis of ITS, gapdh, chs-1, act, and tub2 sequence data coupled with Genealogical Concordance Phylogenetic Species Recognition Analysis (GCPSRA) supported the two strains as two distinct species within the gloeosporioides species complex. The three Colletotrichum species were compared and differentiated with closely related taxa. Koch’s postulates were proven, demonstrating that C. avicenniae, C. lumnitzerae, and C. tropicale cause anthracnose leaf spots in mangroves. Understanding the classification and etiology of these fungal pathogens will contribute to a more comprehensive knowledge of mangrove biology within the marine ecosystem.

红树林在海洋生态系统中发挥着重要作用，并蕴藏着大量对各种生态功能至关重要的微生物。然而，它们仍然容易受到真菌植物病原体造成的破坏性影响。在这项研究中，从泰国班武里府的红树林中收集了出现炭疽病症状的叶子。使用多相方法鉴定了三个物种，即两个新物种——来自白骨壤的Colletotrichum avicenniae、来自Lumnitzeraracemosa的Colletotrichum lumnitzerae和一个已知物种Colletotrichumtropicale。ITS、gapdh、chs-1、act和tube2序列数据的综合分析以及系谱一致性系统发育物种识别分析 (GCPSRA) 支持这两种菌株作为胶孢菌物种复合体中的两个不同物种。将三个炭疽菌属物种与密切相关的分类群进行比较和区分。科赫的假设得到了证明，表明C. avicenniae、C. lumnitzerae和C.tropice会导致红树林炭疽病叶斑。了解这些真菌病原体的分类和病因学将有助于更全面地了解海洋生态系统内的红树林生物学。