Contrasting power of the factors for fission and sexuality in a polyploid planarian

  • Giuseppina Benazzi Lentati
  • Mario Benazzi
Conference paper
Part of the Developments in Hydrobiology book series (DIHY, volume 6)


One of the biotypes of the planarian Dugesia benazzii is triploid in the somatic line, hexaploid in the female line owing to a chromosome set doubling, and diploid in the male line due to a haploid set elimination. In a population of this biotype only 50% of the oocytes are hexaploid, the others being triploid as a results of the lack of set doubling; the male line is always diploid. After a long period of laboratory culture most of the individuals became asexual and fissiparous. Almost all the oocytes of the few specimens which have remained sexual showed triploid complement; B-chromosomes also appeared. These events represent the manifestation of a new genetic background which act upon the two germ lines in different ways and moments. These topics are discussed.


Turbellaria Dugesia reproduction karyology 


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Copyright information

© Dr W. Junk Publishers, The Hague 1981

Authors and Affiliations

  • Giuseppina Benazzi Lentati
    • 1
  • Mario Benazzi
    • 1
  1. 1.Institute of ZoologyUniv. of PisaPisaItaly

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