Trigona (Tetragonula) sirindhornae new species is described on the basis of specimens from the Isthmus of Kra. It is most similar to the Bornean T. melanocephala Gribodo but is also similar to the wider ranging T. drescheri Schwarz; it differs most conspicuously from both in the contrast between the black scutum and the testaceous scutellum (Figs. 1–3).