Novel endophytic fungi from Pinus: introducing three new genera and six new species within Capnodiales (Ascomycota, Dothideomycetes) sensu lato

Capnodiales s. lat., the second largest order within the Dothideomycetes, comprises a highly diverse group of species exhibiting considerable morphological and phylogenetic diversity. In this study, we examined more than 800 fungal isolates from shoots of three species of healthy pine trees (Pinus densiflora Siebold & Zucc., P. thunbergii Parl., and P. elliottii Engelm.) in China, leading to the establishment of several novel taxa with Capnodiales s. lat ..

The species were identified through morphological characterisation and phylogenetic analyses based on concatenated sequence of seven loci: the internal transcribed spacer (ITS) regions, the large subunit nuclear ribosomal RNA gene (nLSU), the RNA polymerase II subunit B (RPB 2), the actin gene (ACT), the calmodulin gene (CAL), the ß-tubulin gene (TUB) and the elongation factor 1 - alpha gene (TEF 1). As a result, three novel genera — Botryoconidia (Dissoconiaceae), Longisporomyces (Extremaceae), and Helianthoconium (Mycosphaerellaceae) are proposed, along with nine novel species: Botryoconidia globosus, Longisporomyces filisporum, Neocatenulostroma endophyticum, Rachicladosporium pennatum, Helianthoconium helianthosporum, Sphaerulina nanjingensis, Toxicocladosporium fusiforme, Zasmidium guttulatum, and Zasmidium longisporum.

Furthermore, we employed fossil calibrations to estimate divergence times of these taxa within Capnodiales s. lat. The results suggest that the crown age of Capnodiales was around 241.9 Mya (95 % HPD: 239.23–243.18 Mya), in the Middle Triassic. The major subclades such as Capnodiales s. str., Cladosporiales and Mycosphaerellales began diversifying during the Jurassic, with crown ages estimated at 169.56 Mya, 148.60 Mya, 187.18 Mya, respectively.

This study provides comprehensive descriptions of these new endophytic taxa from pine hosts, contributing to the taxonomic and systematic understanding of the Capnodiales s. lat.