Nearly June, and the first worthwhile trip of the year...I think!
I think this is Caltoris tulsi, but, as it would be a new record for the Islands, I would appreciate confirmation. The pale hindwing discal patch and forewing costa seem to indicate the species. Also it was found near the highest point of the Island, c.550m.
Thank you, the tiring walk up hill under the sun was worth it after all, though I will not be doing that again in a hurry! This new location is also the home of Hasora zoma and Telicota hilda, which were actually what I was going up to find (and failed). A Japanese friend who regularly visits Samui found it there and showed me the specimens, no doubt!