Molecular Phyloigeny of Sarcophyton and Lobophytum (Cnidaria: Octocorallia: Alcyonaria: Alcyoniidae)

Sarcophyton and Lobophytum are two common soft coral genera on Indo-Pacific coral reefs. Traditionally, their taxonomy is based on colony shapes and the variety and morphology of sclerites. However, in some cases the taxanomy between these two genera is vague. In addition, species of the two genera share a synapomorphy, i.e., the dimorphic polyps. Whether they are monophyletic remains to be studied. Samples of Sarcophyton and Lobophytum from southern Taiwan and Ludao were collected. Protein-coding genes [NADH-dehydrogenase subunits 6 (ND6), and mutS homolog (msh1), 1379 bp] were used to study their phylogeny. Among the total 250 variable sites, 169 and 81 were found in msh1 and ND6, respectively. These sequences (n = 62) were analyzed using maximum-likelihood and neighbor-joining methods in MEGA 3.1 (PC version). Phylogenetic trees reconstructed by both methods revealed a similar pattern suggesting that these two genera are not monophyletic (<5% sequence divergence). This phenomenon might be due to incomplete lineage sorting, reticulate evolution, or the inconsistency between morphological and molecular evolution.