Re-evaluation of the systematics of two deep-sea species of Thalassometra (Echinomermata: Crinoidea) and its biogeographical implications

• Published in: Journal of Natural History
• Main Authors: Eléaume, Marc, Améziane, Nadia, Park, Young-Hyang
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2004
• Subjects: geo; envir; Campbell Plateau; Pacific; Southern Ocean; Aleutian Islands
• Online Access: https://doi.org/10.1080/0022290310001613566; https://hal.archives-ouvertes.fr/hal-00164911

Biogeography of deep-sea comatulid crinoids is poorly understood owing partly to the lack of detailed taxonomic studies. Recent cruises off Peru dredged up two new, well-preserved specimens of Thalassometra bispinosa, a deep-sea comatulid species which was heretofore only known from the Southern Ocean. These new records enabled re-evaluation of intra-specific variation for both quantitative and qualitative morphological characters. We thus provide a new description of the species, including these new specimens, and discuss the affinities with closely related species. As a consequence, we re-evaluate the systematic position of material previously assigned to T. bispinosa dredged from the Campbell Plateau, Southern Ocean. Discrete morphological characters, measurements and SEM photographs justify reassignment of these specimens to Thalassometra villosa. This species, another poorly known deep-sea comatulid crinoid previously known only from the Aleutian Islands in the North Pacific, is also redescribed. The biogeography of these two deep-sea comatulid species is discussed and hypotheses of their geographical distribution are proposed.