Watanabe Hiromi Kayama, Chen Chong, Marie Daniel P, Takai Ken, Fujikura Katsunori, Chan Benny K K
Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan.
Department of Subsurface Geobiological Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan.
R Soc Open Sci. 2018 Apr 18;5(4):172408. doi: 10.1098/rsos.172408. eCollection 2018 Apr.
Phylogeography of animals provides clues to processes governing their evolution and diversification. The Indian Ocean has been hypothesized as a 'dispersal corridor' connecting hydrothermal vent fauna of Atlantic and Pacific oceans. Stalked barnacles of the family Eolepadidae are common associates of deep-sea vents in Southern, Pacific and Indian oceans, and the family is an ideal group for testing this hypothesis. Here, we describe sp. nov. from the Indian Ocean, distinguished from and by having a tridentoid mandible in which the second tooth lacks small elongated teeth. Morphological variations suggest that environmental differences result in phenotypic plasticity in the capitulum and scales on the peduncle in eolepadids. We suggest that diagnostic characters in Eolepadidae should be based mainly on more reliable arthropodal characters and DNA barcoding, while the plate arrangement should be used carefully with their intraspecific variation in mind. We show morphologically that specimens collected from the South West Indian Ridge, the South East Indian Ridge and the Central Indian Ridge belong to the new species. Molecular phylogeny and fossil evidence indicated that migrated from the southern Pacific to the Indian Ocean through the Southern Ocean, providing key evidence against the 'dispersal corridor' hypothesis. Exploration of the South East Indian Ridge is urgently required to understand vent biogeography in the Indian Ocean.
动物系统地理学为支配其进化和多样化的过程提供了线索。印度洋被假定为连接大西洋和太平洋热液喷口动物群的“扩散走廊”。艾氏茗荷科的有柄茗荷是南大洋、太平洋和印度洋深海喷口的常见伴生物种，该科是检验这一假说的理想类群。在此，我们描述了一种来自印度洋的新物种，它与其他物种的区别在于具有三叉形的大颚，其中第二颗齿没有小的细长齿。形态学变异表明，环境差异导致艾氏茗荷科头状部和柄上鳞片的表型可塑性。我们建议，艾氏茗荷科的诊断特征应主要基于更可靠的节肢动物特征和DNA条形码，同时在考虑到其种内变异的情况下谨慎使用板的排列方式。我们从形态学上表明，从西南印度洋海岭、东南印度洋海岭和中印度洋海岭采集的标本属于新物种。分子系统发育和化石证据表明，该物种从南太平洋经南大洋迁移至印度洋，为反对“扩散走廊”假说提供了关键证据。迫切需要对东南印度洋海岭进行勘探，以了解印度洋的喷口生物地理学。
