title: High levels of morphological variation despite close genetic relatedness between Zoanthus aff. vietnamensis and Zoanthus kuroshio (Anthozoa: Hexacorallia).
abstract: Recent investigations into the encrusting anemone genus Zoanthus using molecular and morphological techniques have begun to bring order to this taxonomically neglected group. Previous studies have confirmed the existence of three distinct species present in southern Japan: Z. sansibaricus, Z. kuroshio, and Z. gigantus. Results from such studies show species of Zoanthus to be highly morphologically plastic, often incorporating morphotypes with varying oral disk color and oral disk diameter. Literature lists the species Z. aff. vietnamensis as occurring in southern Japan and throughout the western Pacific Ocean, but due to the morphological plasticity of Zoanthus species, a re-examination of Z. aff. vietnamensis using molecular techniques was needed. Here, using mitochondrial 16S rDNA and the nuclear internal transcribed spacer of ribosomal DNA (ITS-rDNA) sequences, as well as morphological data, we have examined several nominal Z. aff. vietnamensis samples collected from Kagoshima Bay and Yakushima Island, Japan. Based on polyp length and diameter, oral disk diameter, mesentery and tentacle numbers, and colony form, Z. aff. vietnamensis is easily distinguishable from Z. sansibaricus, Z. kuroshio, and Z. gigantus. However, despite these clear morphological differences, our mitochondrial and nuclear sequence-based phylogenies indicate that Z. aff. vietnamensis and Z. kuroshio are very closely related (perhaps conspecific), highlighting the morphological plasticity of this genus and the difficulty of species identification based on morphological data alone.
authors.affiliation: Research Program for Marine Biology and Ecology, Extremobiosphere Research Center, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan. jreimer@jamstec.go.jp
authors.forename: James Davis
authors.initials: JD
authors.lastname: Reimer
authors.forename: Shusuke
authors.initials: S
authors.lastname: Ono
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iwama
authors.forename: Junzo
authors.initials: J
authors.lastname: Tsukahara
authors.forename: Tadashi
authors.initials: T
authors.lastname: Maruyama
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure*; D044822:Biodiversity; D004247:DNA / Q000737:chemistry; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D004463:Ecology; D007564:Japan; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D013045:Species Specificity
chemical_list: D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D004247:DNA