Seamounts as potential stepping stones for the dispersal of meiobenthos. Comparative taxonomic, faunistic, and biogeographic studies of the Kinorhyncha from different seamounts and islands of the north eastern Atlantic and the Mediterranean

• Applicants: Dr. Kai Horst George; Dr. Birger Neuhaus
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Systematics and Morphology (Zoology)
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 283080919

• Final Report Year: 2019

Final Report Abstract

Kinorhyncha (mud dragons) is a group of meiofaunal organisms with a body length of 0.1-1.2 mm living exclusively in brackish and marine sediments from intertidal waters to the deepest deep sea. The species develop via a series of benthic juvenile stages and lack any pelagic free-living larvae. This life cycle excludes the possibility of distribution via pelagic larvae. For meiofaunal mites (Halacaridae, life cycle without pelagic larvae) and several crustaceans (Copepoda Harpacticoida, Canuelloida, live cycle without pelagic larvae) it was suggested that seamounts may represent stepping stones for the dispersal of these animals. Therefore, seven seamounts in the northeastern Atlantic Ocean, Mediterranean Sea, and Arctic Sea were investigated for the species composition of Kinorhyncha and species new to science described. The fauna of Kinorhyncha on seamounts was to some degree unique and to some degree similar to the fauna of both shallow waters and the deep-sea floor. Several kinorhynch species found on a seamount were probably seamount-endemic species. From the distribution pattern of seamounts species and their relatives, seamount kinorhynchs seem have originated from three different environments: (1) some species probably originated from shallow coastal waters and dispersed widely using seamounts as stepping stones (Echinoderes adrianovi, E. apex, E. multiporus, E. peterseni), (2) some species inhabited a broad depth range from seamounts to the deep-sea floor and possibly originated from the deep sea (Echinoderes bathyalis, E. pterus, E. unispinosus, Sphenoderes aspidochelone), and (3) few kinorhynch species may have evolved on a seamount (Echinoderes schwieringae, E. multiporus). Data about the kinorhynch fauna on continental shelves, seamounts, and the deep-sea floor is still very limited. In addition, very recent studies indicate that species of Kinorhyncha seem to possess a much broader range of variation of morphological characters than anticipated in the past, thus suggesting that at least some "closely related" species may turn out to represent just one species. Future investigations should focus on both detailed population studies and large-scale distribution records of kinorhynchs in order to elucidate their mechanisms of dispersal and speciation.

Publications

• (2019) Echinoderid mud dragons (Cyclorhagida: Kinorhyncha) from Senghor Seamount (NE Atlantic Ocean) including general discussion of faunistic characters and distribution patterns of seamount kinorhynchs. Zoologischer Anzeiger 282 64–87
  Yamasaki, Hiroshi; Neuhaus, Birger; George, Kai Horst
  
• (2019) Investigation of echinoderid kinorhynchs described 90 years ago: redescription of Echinoderes capitatus (Zelinka, 1928) and Echinoderes ferrugineus Zelinka, 1928. Zoologischer Anzeiger 282 189–205
  Yamasaki, Hiroshi; Dal Zotto, Matteo
  
• (2019) The genus Condyloderes (Kinorhyncha: Cyclorhagida) in the Mediterranean Sea, including the description of two new species with novel characters. Zoologischer Anzeiger 282 206–231
  Dal Zotto, Matteo; Neuhaus, Birger; Yamasaki, Hiroshi; Todaro, M. Antonio
  
• (2018) Echinoderes antalyaensis sp. nov. (Cyclorhagida: Kinorhyncha) from Antalya, Turkey, Levantine Sea, Eastern Mediterranean Sea. Species Diversity 23: 193–207
  Yamasaki H., Durucan F.
  
• (2018) Echinoderes pterus sp. nov. (Kinorhyncha, Cyclorhagida) showing a geographically and bathymetrically wide distribution pattern on seamounts and on the deep-sea floor in the Arctic Ocean, Atlantic Ocean, and Mediterranean Sea. Zookeys 771: 15–40
  Yamasaki H., Grzelak K., Sørensen M.V., Neuhaus B., George K.H.
  
• (2018) New species of Echinoderes (Kinorhyncha: Cyclorhagida) from Mediterranean Seamounts and from the deep-sea floor in the Northeast Atlantic Ocean, including notes on two undescribed species. Zootaxa 4387: 541–566
  Yamasaki H., Neuhaus B., George K.H.
  
• (2018) Three new species of Echinoderidae (Kinorhyncha: Cyclorhagida) from two seamounts and the adjacent deep-sea floor in the Northeast Atlantic Ocean. Cahier de Biologie Marine 59: 79–106
  Yamasaki H., Neuhaus B., George K.H.