Environmental Biology of Fishes

, Volume 73, Issue 3, pp 293–297 | Cite as

An X1X1X2X2/X1X2Y multiple sex chromosome system in a new speciesof the genus Gymnotus (Pisces, Gymnotiformes)

  • Elisangela Bellafronte da Silva
  • Vladimir Pavan Margarido


We characterize the karyotype of Gymnotus sp., an undescribed fish species from the Paraná River. The diploid number is 2n = 40 chromosomes for females and 2n = 39 chromosomes for males, showing a multiple sex chromosome system of the X1X1X2X2/X1X2Y type, a first description in the genus Gymnotus. The nucleolar organizing regions sites are located in only one chromosome pair, a common feature among Gymnotiformes, and heterochromatin is present in the centromeric region of all chromosomes. Although the metacentric neo-Y chromosome appears to have arisen by centric fusion in three species from different Gymnotiformes families, the presence of the X1X1X2X2/X1X2Y sex chromosome system seems to be a homoplasic event in this group.

Key words

Gymnotidae cytogenetics chromosomal evolution 


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Copyright information

© Springer 2005

Authors and Affiliations

  • Elisangela Bellafronte da Silva
    • 1
  • Vladimir Pavan Margarido
    • 2
  1. 1.Departamento de Genètica e EvoluçãoUniversidade Federal de São CarlosSão CarlosBrazil
  2. 2.Centro de Ciências Biológicas e da SaúdeUniversidade Estadual do Oeste do ParanáCascavelBrazil

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