Definition of "telson"

telson

noun
plural telsons
1. (zoology) The part of an arthropod or crustacean posterior to the last segment, often resembling an armored tail or tip of the tail.
  Quotations
  Although Crangonya evidently comes very close to Niphargus, it appears to be a good genus, and to differ constantly from Niphargus in the more robust body and in the telson, which is always entire and never cleft as in Niphargus.
  1894, Charles Chilton, “The Subterranean Crustacea of New Zealand”, in Transactions of the Linnean Society of London, 2nd Series, Volume VI: Zoology, Linnean Society of London, page 219
  The basic number of segments in the abdomen is eleven plus the postsegmental telson which bears the anus, although Matsuda (1976) regards the telson as a twelfth segment.
  1998, R. F. Chapman, The Insects: Structure and Function, 4th edition, Cambridge University Press, page 259
  The two documented examples of telson abnormalities are on juvenile moults (Fig. 2a, b).
  2022, Russell D. C. Bicknell et al., “Applying Records of Extant and Extinct Horseshoe Crab Abnormalities to Xiphosurid Conservation”, in John T. Tanacredi et al., editors, International Horseshoe Crab Conservation and Research Efforts: 2007-2020, Springer, page 88