Systematics and phylogeny of Euryalida (Ophiuroidea) and evolution of the morphology of arms

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Taxonomy and phylogeny of the order Euryalida (Echinodermata, Ophiuroidea) were studied based on DNA and morphology using about 2400 specimens. One new genus and 6 new species, 1 junior synonym genus, and 11 junior synonym species were described, and a total of 112 species of 33 genera were distributed in western North Pacific. Molecular phylogeny analysis of 83 species based on a total of 2917 bp of nuclear 18S rRNA, and mitochondrial 16S rRNA and COI indicated that the family Asteroschematidae are paraphyletic. Clades recognized by molecular phylogeny were also supported by clear taxonomical features. The morphology of ossicles observed by scanning electron microscopy was a very effective and stable taxonomical character. A new systematics (2 superfamilies, 5 families, 3 subfamilies) of the order Euryalida was proposed based on molecular and morphological data. Arm branching was evolved not once but in many times for euryalid ophiuroids.