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Hydrobiologia

, Volume 558, Issue 1, pp 9–21 | Cite as

Encystment Processes and the “Matrioshka-like Stage” in a Moss-dwelling and in a Limnic Species of Eutardigrades (Tardigrada)

  • Roberto Guidetti
  • Deborah Boschini
  • Lorena Rebecchi
  • Roberto Bertolani
Article

Abstract

Tardigrades have two forms of dormancy, namely cryptobiosis and encystment. The encystment is a form of diapause known for a limited number of species of tardigrades and still little studied. To increase the knowledge on encystment, two species of eutardigrades from Italy have been considered: the moss-dwelling Amphibolus volubilis (Eohypsibiidae), and the limnic Dactylobiotus parthenogeneticus (Murrayidae). Cysts have been collected in nature, or induced under laboratory conditions. In the latter case, it was possible to follow the several steps of encystment processes. Two different types of cyst (“type 1” and “type 2”) have been found in A. volubilis, while in D. parthenogeneticus only one type has been found. In general, the ovoid-shaped cysts are constituted by a series of cuticles surrounding the animals and resemble an onion or a Matrioshka Russian doll. In all three types of cyst, the encystment processes show both common and peculiar traits. Encystment begins with the discharging of the sclerified parts of the buccal-pharyngeal apparatus, as in the molting process, but without the loss of the old cuticle. Then, two or three new cuticles are serially synthesized, according to cyst type. In A. volubilis, the ultrastructure of these new cuticular involucra is similar to that of non-encysted animal cuticles, while in D. parthenogeneticus the ultrastructure of the new cuticular involucra differs from that of non-encysted animal cuticle. A modified buccal-pharyngeal apparatus has been observed both in “type 2” cyst of A. volubilis and in the D. parthenogeneticus cyst.

Keywords

dormancy diapause encystment Dactylobiotus parthenogeneticus Amphibolus volubilis 

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Copyright information

© Springer 2006

Authors and Affiliations

  • Roberto Guidetti
    • 1
  • Deborah Boschini
    • 1
  • Lorena Rebecchi
    • 1
  • Roberto Bertolani
    • 1
  1. 1.Department of Animal BiologyUniversity of Modena and Reggio EmiliaModenaItaly

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