Morphology and molecular phylogeny reveal new species of Sporocadus (Sporocadaceae, Amphisphaeriales) in Xizang, China

Sporocadus is the type genus of Sporocadaceae and is phylogenetically closely related to Seimatosporium. Traditionally, these two genera were distinguished by the presence or absence of conidial appendages; however, this morphological character is sometimes plastic and unstable. Previous studies have also shown that internal transcribed spacer (ITS) and large subunit (LSU) sequence data are insufficient for their resolution.

In this study, fungal specimens were collected from branches of two rosaceous hosts, Prunus cerasifera and Rosa chinensis, in Xizang, China. Based on morphological examination and multi-locus phylogenetic analyses of a combined ITS, LSU, rpb 2, tef 1, and tub 2 dataset, two new species are revealed and described herein as Sp. bomiensis and Sp. prunicola spp. nov. Furthermore, Seimatosporium parvum, which possesses distinct conidial appendages, is transferred to Sporocadus as Sp. parvus comb. nov. based on strong molecular evidence.

Given the limited resolution of ITS and LSU and the instability of conidial appendages, we suggest that five-loci datasets including all accepted species are essential for accurate identification within the Sporocadus – Seimatosporium complex. This study not only expands the species diversity of Sporocadus in high-altitude regions but also provides new insights into the taxonomy and identification of pestalotioid fungi.