Phylogenetic and morphological reassessment of Sporidesmium-related taxa reveals Lignosporidesmium gen. nov. and Xenosporidesmium lignicola sp. nov.

Sporidesmium sensu lato comprises several phylogenetically divergent lineages. Although lineages such as Distoseptispora and Xenosporidesmium have been intensively studied, others remain poorly resolved owing to incomplete type material, limited population sampling, or the absence of molecular data. In this study, Sporidesmium -related taxa were investigated using a multigene phylogenetic framework based on combined LSU, ITS, rpb 2, SSU, and tef 1-α sequence data, which resolved seven distinct phylogenetic lineages. Based on integrative evidence from morphology and phylogeny, a new species, Xenosporidesmium lignicola , is described, and a new genus, Lignosporidesmium , is introduced to accommodate L. tropicale (≡ Sporidesmium tropicale ). In addition, nine new combinations are proposed, including Lylea lignicola , Xenosporidesmium bostenicum , X. dianchiense , X. distoseptatum , X. hongheense , X. lacustris , X. mucilaginosum , X. yangzonghaiense , and X. yilonghuense . Furthermore, the phylogenetic structure and classification of Sporidesmium -related groups are comprehensively discussed from both morphological and multigene phylogenetic perspectives. Distinctive morphological characters, including conidiogenesis, septum type, and the presence or absence of sheaths or appendages, are evaluated in relation to their phylogenetic placements. The boundaries and relationships among Ellisembia , Lylea , Sporidesmium , Xenosporidesmium , and related historical and newly established taxa are critically assessed. However, the taxonomic positions of several lineages remain uncertain due to missing type materials or a lack of molecular data, highlighting the need for re-collection, detailed morphological re-examination, and the generation of fresh sequence data. Overall, the pronounced morphological diversity and limited molecular representation of many historically described species underscore the challenges in achieving a stable and comprehensive classification, emphasizing the necessity of integrative taxonomic approaches combining morphology, fresh collections, and multigene phylogenetic analyses.