Journal Molluscan Studies Advance Access originally published online on May 26, 2006
Journal of Molluscan Studies 2006 72(3):295-309; doi:10.1093/mollus/eyl007
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Anatomy of Bathyacmaea secunda Okutani, Fujikura & Sasaki, 1993 (Patellogastropoda: Acmaeidae)
1 The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 113-0033; and 2 Japan Agency for Marine-Earth Science & Technology, 2-15 Natsushima, Yokosuka, Kanagawa Prefecture, Japan 237-0061
Correspondence: T. Sasaki; e-mail: sasaki{at}um.u-tokyo.ac.jp
Anatomy of a vent-endemic patellogastropod limpet, Bathyacmaea secunda, was examined by gross dissection and serial sections. It was revealed that B. secunda is anatomically distinct from other patellogastropod taxa in that (1) the intestine runs through the ventricle; (2) the ventral approximator muscle of odontophoral cartilages is ventrally single-layered; (3) there is a pair of radular teeth with long shafts; and (4) the statocysts are isolated from pleural and pedal ganglia. In addition, the species is characterized by short pallial margin papillae, lack of pallial streaks, presence of a ctenidium, obliquely tubular salivary glands, simple gut configuration and acmaeoidean type of buccal mass musculature and odontophoral cartilages. The comparison in anatomical and shell microstructural characters suggests that B. secunda shares no unique similarities with the Patelloidea or Neolepetopsidae and, therefore, is not closely related to these groups. In contrast, a number of similarities were found between B. secunda and acmaeid species. These results support the current systematic position of Bathyacmaea within the Acmaeidae, although anatomical data from some related genera are still insufficient.
(Received 3 September 2005; accepted 25 January 2006)