[1] Found only in a specific region of Thailand, it is closely related to Astrochapsa recurva, yet distinguishes itself through its narrower ascospores and absence of secondary metabolites.

The type specimen was collected at Khok Nok Kraba ranger station in Thailand's Phu Luang Wildlife Sanctuary, on the bark of Rhododendron simsii in low-mountain scrubland.

[2] Astrochapsa elongata features a corticolous thallus that can grow up to 5 cm (2 in) in diameter and 30–60 μm thick.

Other similar species include Astrochapsa zahlbruckneri, Chapsa cinchonarum, and Pseudochapsa dilatata, which can be distinguished by their ascospore characteristics.

[2] Astrochapsa elongata has been found on the trunk of Rhododendron simsii in northeastern Thailand, specifically in the lower montane scrub.