Gilbert Rahm and the status of Mesotardigrada Rahm, 1937

Gary T. Grothman, Carl Johansson, Glen Chilton, Hiroshi Kagoshima, Megumu Tsujimoto, Atsushi C. Suzuki

Research output: Contribution to journalReview articlepeer-review

16 Citations (Scopus)


The tardigrade class Mesotardigrada was erected on the basis of the description of Thermozodium esakii by Gilbert Rahm in 1937. In some characteristics, T. esakii is intermediate between members of the classes Eutardigrada and Heterotardigrada. The class Mesotardigrada is known only from Rahm's published drawings of T. esakii; no voucher specimens are known, and subsequent attempts to collect it at the locus typicus have been unsuccessful. Among the possible explanations for this situation are that Rahm may have collected specimens of a more typical tardigrade, but misinterpreted what he saw. Alternatively, changes in habitat in the area may have led to the tardigrade's extirpation. Perhaps T. esakii is a rare species, such that recent sampling efforts have been insufficient to rediscover it. Finally, Rahm's 1937 description may be an attempt at deception. Until physical evidence of T. esakii is found, the species, and by extension the class Mesotardigrada, should be considered nomen dubium.

Original languageEnglish
Pages (from-to)5-10
Number of pages6
JournalZoological Science
Issue number1
Publication statusPublished - 2017 Feb


  • Hot spring
  • Mesotardigrada
  • Nomen dubium
  • Tardigrada
  • Thermozodium

ASJC Scopus subject areas

  • Animal Science and Zoology


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