Molecular phylogeny of the antitropical subgenus Goniistius (Perciformes: Cheilodactylidae: Cheilodactylus):: evidence for multiple transequatorial divergences and non-monophyly

The subgenus Gonustius comprises eight species of marine nearshore fishes which are antitropically distributed. The molecular phylogeny of these and other cheilodactylids was reconstructed from cytochrome oxidase I and cytochrome b mitochondrial DNA sequences. The placement within Gonustius of the morphologically divergent species Cheilodactylus (G.) nigripes was not supported. The remaining seen species are sufficiently; divergent from other cheilodactylids to be designated as a separate genus, The antitropical distribution of Gonustius is the result of three transequatorial divergences, which occurred during two periods. Based on molecular clock calibrations, these periods are suggested to he the mid Miocene, and late Miocene to early Pliocene. It is not known in which direction or by which mechanism these transequatorial divergences occurred, although biogeographic hypotheses of Mesozoic or Pleistocene separations can be discounted. The degree of genetic divergence between North and South Pacific populations of C. (G.) vittatus Garrett indicates that they have undergone cryptic speciation. (C) 2000 The Linnean Society of London.