Two new lichen species, Astrochapsa pruinosa and Ramonia sirindhorniana, are described from Thailand. Astrochapsa pruinosa has angular-rounded to elongate ascomata, 8-spored asci, and muriform ascospores (30–45 × 12–15 µm), differing from the similar A. pseudophlyctis, which has predominantly rounded ascomata and 1–6-spored asci. Ramonia sirindhorniana is characterized by simple, ellipsoid ascospores (6–8 × 3–4 µm) and 16–32-spored asci. It is distinguished from R. kandleri by its smaller ascospores and ascomata and fewer ascospores per ascus. Acanthothecis tetraphora is reported as a new record for Asia. Keywords: Asia, diversity, taxonomy, tropical lichens.