A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella

BMC Evolutionary Biology

Research Article

Ryo Koyanagi¹  Miyuki Kanda¹  Keiichi Kakui²  Toshihiko Shiroishi³  Akiteru Maeno³  Noriyuki Satoh⁴  Hisanori Kohtsuka⁵  Akihito Omori⁶  Hiroaki Nakano⁷  Hideyuki Miyazawa⁷ 

[1] DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, 904-0495, Okinawa, Japan;Faculty of Science, Hokkaido University, N10 W8, Kita-ku, 060-0810, Sapporo, Hokkaido, Japan;Mammalian Genetics Laboratory, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan;Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, 904-0495, Okinawa, Japan;Misaki Marine Biological Station, The University of Tokyo, 1024 Koajiro, Misaki, 238-0225, Miura, Kanagawa, Japan;Misaki Marine Biological Station, The University of Tokyo, 1024 Koajiro, Misaki, 238-0225, Miura, Kanagawa, Japan;Present address: Sado Marine Biological Station, Faculty of Science, Niigata University, Sado, 952-2135, Niigata, Japan;Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, 415-0025, Shizuoka, Japan;

关键词: Xenoturbella;    Acoels;    Nemertodermatids;    Acoelomorpha;    Xenacoelomorpha;    Frontal organ;    Deuterostomes;    Bilaterians;    Metazoans;    Evolution;   

DOI  :  10.1186/s12862-017-1080-2

 received in 2017-06-07, accepted in 2017-11-16,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundXenoturbella is a group of marine benthic animals lacking an anus and a centralized nervous system. Molecular phylogenetic analyses group the animal together with the Acoelomorpha, forming the Xenacoelomorpha. This group has been suggested to be either a sister group to the Nephrozoa or a deuterostome, and therefore it may provide important insights into origins of bilaterian traits such as an anus, the nephron, feeding larvae and centralized nervous systems. However, only five Xenoturbella species have been reported and the evolutionary history of xenoturbellids and Xenacoelomorpha remains obscure.ResultsHere we describe a new Xenoturbella species from the western Pacific Ocean, and report a new xenoturbellid structure - the frontal pore. Non-destructive microCT was used to investigate the internal morphology of this soft-bodied animal. This revealed the presence of a frontal pore that is continuous with the ventral glandular network and which exhibits similarities with the frontal organ in acoelomorphs.ConclusionsOur results suggest that large size, oval mouth, frontal pore and ventral glandular network may be ancestral features for Xenoturbella. Further studies will clarify the evolutionary relationship of the frontal pore and ventral glandular network of xenoturbellids and the acoelomorph frontal organ. One of the habitats of the newly identified species is easily accessible from a marine station and so this species promises to be valuable for research on bilaterian and deuterostome evolution.

【 授权许可】

CC BY   
© The Author(s). 2017