The Philippine species of the subgenus Symplecthyma Rivalier, 1964 within the genus Prothyma Hope, 1838 are revised to include eight species. Prothyma (Symplecthyma) bella Dheurle & Colas, 2018 syn. nov. is synonymized with Prothyma (Symplecthyma) coerulea opacosericea Horn, 1929 comb. nov.; Prothyma (Symplecthyma) boholensis Dheurle, 2012 syn. nov. and P. (Symplecthyma) nitida Rivalier, 1964 syn. nov. are synonymized with Prothyma (Symplecthyma) aeneoparva Horn, 1934. Four new species from Mindanao are described: Prothyma (Symplecthyma) inopinata sp. nov., Prothyma (Symplecthyma) eureka sp. nov., Prothyma (Symplecthyma) sciakyi sp. nov. and Prothyma (Symplecthyma) kapuka sp. nov. Taxonomic problems in the subgenus Symplecthyma are discussed. Keys to species are provided. Color photographs of the habitus and diagnostic characters, including their variability among all species, are presented.