This revision of Indonesian Millepora species is based on the morphology of museum specimens and photographed specimens in the field. Based on the use of pore characters and overall skeleton growth forms, which are normally used for the classification of Millepora, the present study concludes that six of seven Indo-Pacific species appear to occur in Indonesia, viz., M. dichotoma Forskal, 1775, M. exaesa Forskal, 1775, M. platyphylla Hemprich & Ehrenberg, 1834, M. intricata Milne-Edwards, 1857 (including M. intricata forma murrayi Quelch, 1884), M. tenera Boschma, 1949, and M. boschmai de Weerdt & Glynn, 1991, which so far was considered an East Pacific endemic. Of the 13 species previously reported from the Indo-Pacific, six were synonymized. M. murrayi Quelch, 1884, has been synonymized with M. intricata, which may show two distinct branching patterns, that may occur in separate corals or in a single one. M. latifolia Boschma, 1948, M. tuberosa Boschma, 1966, M. cruzi Nemenzo, 1975, M. xishaensis Zou, 1978, and M. nodulosa Nemenzo, 1984, are also considered synonyms. M. foveolata Crossland, 1952, is a distinct species but it has not been found in Indonesia.
Zoogeography, Biogeography (generalities), Geographic distribution