Novel genus and species of Diaporthostomataceae (Diaporthales) in China

Diaporthales is a significant fungal order comprising species that predominantly inhabit plant tissues, being pathogens, endophytes, and saprobes. Recent studies have uncovered extensive species diversity across various hosts, utilizing both morphological characteristics and molecular phylogenetic analyses. In this study, samples of leaf spots and branch cankers were collected from China, and fungal isolations were established. Species identification was conducted using a phylogenetic approach based on combined sequence data from the internal transcribed spacer (ITS) region, large subunit ribosomal DNA (LSU), the DNA-directed RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1) genes, together with morphological observations. As a result, the novel genus Tiania is proposed, with three newly described species: T. chinensis, T. lithocarpicola, and T. quercicola. These species are validated by pairwise homoplasy index (PHI) analysis, ensuring robust support for their distinction. This study explores the rare family Diaporthostomataceae, providing the first descriptions of their anamorphic forms. By offering detailed morphological and molecular data, this research lays a foundation for future taxonomic and systematic studies of the Diaporthales.