Lack of morphological features of diagnostic value and high levels of environmental phenotypic plasticity obscure species boundaries for most taxa in the genus Pocillopora Lamarck, 1816 and complicate the definition of taxonomically distinct units. Species of the genus are colonial, generally ramose, rarely massive or encrusting and mostly hermatypic; corallite arrangement is plocoid, septa are generally poorly developed and usually arranged in two cycles; the columella is mostly poorly developed (Veron & Pichon 1976). Verrucae are common, although reduced in some species. Currently 17 species are formally acknowledged within the genus (Veron 2000). Using a molecular phylogenetic approach, recent studies were able to identify genetically distinct lineages in Pocillopora, indicating that Pocillopora damicornis (Linnaeus, 1751) consists of a cryptic species complex (Souter 2010; Schmidt-Roach et al. 2012a). One of these species, previously considered a temperate ecomorph of P. damicornis, is here described as a novel species, based on its distinct morphology, unique mitochondrial haplotype and incongruity with previously described taxa in P. damicornis. Pocillopora aliciae sp. nov. exhibits a flat, plate-like growth (usually displayed by deep-water morphs of pocilloporids) at all depths, which clearly differentiates it from P. damicornis colonies at subtropical Lord Howe Island or Rottnest Island. Furthermore, Stylophora pistillata Esper, 1797, which is equally known to exhibit flat deep-water morphs, maintains its common gross morphology at equal depth to P. alicae sp.