title: DNA barcoding and morphological analyses revealed validity of Diadema clarki Ikeda, 1939 (Echinodermata, Echinoidea, Diadematidae).
abstract: A long-spined sea urchin Diadema-sp reported from Japanese waters was genetically distinct from all known Diadema species, but it remained undescribed. Extensive field surveys in Japan with molecular identification performed in the present study determined five phenotypes (I to V) in Diadema-sp according to the presence and/or shape of a white streak and blue iridophore lines in the naked space of the interambulacral area. All phenotypes were distinct from Diadema setosum (Leske, 1778) and Diadema savignyi (Audouin, 1829), of which a major type (I) corresponded to Diadema clarki Ikeda, 1939 that was questioned and synonymized with Diadema setosum by Mortensen (1940). The holotype of Diadema clarki has not been found, but three unlabeled dried tests of Diadema were found among Ikeda's original collection held in the Kitakyushu Museum of Natural History and Human History, Fukuoka, Japan. A short mtDNA COI fragment (ca. 350bp) was amplified from one of the tests, and the nucleotide sequence determined (275bp) was nearly identical with that of Diadema-sp. Arrangements of the primary tubercles on the coronal plates in Diadema-sp and the museum specimen also conformed with Diadema clarki, indicating that Diadema-sp is identical to Diadema clarki and a valid species. Narrow latitudinal distribution (31°N to 35°N) of Diadema clarki in Japan was observed, where it co-existed with abundant Diadema setosum and rare Diadema savignyi. No Diadema clarki was found in the southern islands in Japan, such as Satsunan Islands to Ryukyu Islands and Ogasawara Island, where Diadema setosum and Diadema savignyi were commonly observed.
authors.affiliation: National Research Institute of Fisheries Science, 2-12-4 Fukuura, Yokohama, Kanagawa 236-8648, Japan.
authors.forename: Seinen
authors.initials: S
authors.lastname: Chow
authors.affiliation: National Research Institute of Fisheries Science, 2-12-4 Fukuura, Yokohama, Kanagawa 236-8648, Japan.
authors.forename: Kooichi
authors.initials: K
authors.lastname: Konishi
authors.affiliation: National Research Institute of Fisheries Science, 2-12-4 Fukuura, Yokohama, Kanagawa 236-8648, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Mekuchi
authors.affiliation: National Research Institute of Fisheries Science, 2-12-4 Fukuura, Yokohama, Kanagawa 236-8648, Japan.
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Tamaki
authors.affiliation: Tokai University, Shizuoka, Shizuoka 424-8610, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Nohara
authors.affiliation: Ehime University, Matsuyama, Ehime 790-8566, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Takagi
authors.affiliation: Yokosuka Laboratory, National Research Institute of Fisheries Science, Kanagawa 238-0316, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Niwa
authors.affiliation: Yokosuka Laboratory, National Research Institute of Fisheries Science, Kanagawa 238-0316, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Teramoto
authors.affiliation: Yokosuka Laboratory, National Research Institute of Fisheries Science, Kanagawa 238-0316, Japan.
authors.forename: Hisaya
authors.initials: H
authors.lastname: Manabe
authors.affiliation: Yokosuka Laboratory, National Research Institute of Fisheries Science, Kanagawa 238-0316, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kurogi
authors.affiliation: Minami-Izu Laboratory, National Research Institute of Aquaculture, Shizuoka 415-0156, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Minami-Izu Laboratory, National Research Institute of Aquaculture, Shizuoka 415-0156, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ando
authors.affiliation: Shibushi Laboratory, National Research Institute of Aquaculture, Kagoshima 899-7101, Japan.
authors.lastname: Tadao Jinbo
authors.affiliation: Marine and Coastal Research Center, Ochanomizu University, Tateyama, Chiba 294-0301, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kiyomoto
authors.affiliation: Marine and Coastal Research Center, Ochanomizu University, Tateyama, Chiba 294-0301, Japan.
authors.forename: Mamiko
authors.initials: M
authors.lastname: Hirose
authors.affiliation: Kitakyushu Museum of Natural History and Human History, Kitakyushu, Fukuoka 805-0071, Japan.
authors.forename: Michitaka
authors.initials: M
authors.lastname: Shimomura
authors.affiliation: Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kurashima
authors.affiliation: Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Seikai National Fisheries Research Institute, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Setuo
authors.initials: S
authors.lastname: Kiyomoto
keywords: DNA barcoding; Diadema clarki; Diadematidae; Echinoidea