AUTHOR=Zheng Wanrui , Sun Shao’e , Sha Zhongli , Xiao Ning 

TITLE=Three new species and two new records of Echinothuriidae (Echinodermata: Echinothurioida) from seamounts in the Northwest Pacific Ocean: Diversity, phylogeny and biogeography of deep-sea echinothuriids

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1036914

DOI=10.3389/fmars.2022.1036914

ISSN=2296-7745

ABSTRACT=The soft sea urchins Echinothuriidae Thomson, 1872 constitute the most commonly encountered sea urchins in the bathyal environment. The echinothuriids are common and frequently abundant in Indo-West Pacific, but the species diversity is still not completely known yet. Our examination of echinoid specimens collected from seven seamounts in the Northwest Pacific Ocean revealed three new species and two new records. Three new species are described as Araeosoma cucullatum sp. nov., Araeosoma polyporum sp. nov. and Hygrosoma involucrum sp. nov.. The two new records includes two species from the genus Araeosoma. They are distinguished from each other and congeners by the characteristics of the colouring, ambulacrum, interambulacrum, apical system, spines and pedicellariae. The identities of the five species are well supported by genetic distance and phylogenetic analyses based on the mitochondrial c oxidase subunit I (COI) and 16S rRNA. Based on the distribution data Araeosoma, Calveriosoma, Hapalosoma, Sperosoma, Tromikosoma, and Hygrosoma, the six echinothuriid genera occurring in deep sea, we explored their distribution pattern and delineated ten isolated deep-sea biogeographic provinces all over the world. The Western Pacific harbors higher species diversity of deep-sea echinothuriids than other sea areas worldwide, and indicated that the Western Pacific may played an important part in the dispersal and speciation of deep-sea echinothuriids.