Pohnpei is a continental island in central Micronesia with extensive fringing coral reefs (Turak and DeVantier 2005). During a reef coral survey in 2009, we found a shallow (10–20 m) southwest lagoon site (6.93° N, 158.11° E) with a scleractinian reef coral assemblage typical of the mesophotic zone (Kahng et al. 2010; Muir et al. 2015), dominated by deep-water Acropora species [mainly A. pichoni Wallace, 1999 and A. tenella (Brook, 1892)] and large coral plates of the genera Mycedium, Oxypora, Pachyseris and Montipora (Fig. 1). Leptoseris hawaiiensis (Vaughan, 1907) and other ‘deep-water’ species including Acropora elegans (Milne Edwards and Haime, 1860), A. walindii Wallace, 1999, A. batunai Wallace, 1997, A. turaki Wallace, 1994, A. desalwii Wallace, 1994, A. halmaherae Wallace and Wolstenholme, 1998, A. speciosa (Quelch, 1886), A. lokani Wallace, 1994, A. awi Wallace and Wolstenholme, 1998, and A. rongelapensis Richards and Wallace, 2004, were also recorded. Several of the rare Acropora species were previously documented for central Indonesia and northern PNG, some 1500 km to the southwest (Wallace et al. 2012), and therefore show considerable expansion of their recorded biogeographical ranges.