Bilimbia guiyangensis sp. nov. (Ramalinaceae, Lecanoromycetes), a new lichen species from Guiyang, China

Bilimbia guiyangensis sp. nov. is described and illustrated from densely vegetated subtropical forest in Guiyang, China. The new taxon is characterized by a rimose, non‑sorediate thallus, lecideine apothecia, and 3‑septate, relatively long ascospores (13–24 × 4–5 µm). According to phylogenetic analysis of ITS, LSU and mtSSU sequences, the new species is sister to Bilimbia fuscoviridis, from which it differs in having a non‑sorediate thallus (vs. sorediate), lecideine apothecia (vs. biatorine), and longer ascospores (13–24 µm vs. 11.5–17.0 µm in length). This study also provides one of the most comprehensive syntheses of morphological and chemical data for the genus to date, addressing long-standing taxonomic ambiguities and inconsistencies across available descriptions. A detailed tabular comparison of all available species descriptions within the genus is provided to facilitate accurate identification and support future taxonomic and phylogenetic research.