title: Chromosome polymorphism and complements in populations of Girardia species (Platyhelminthes, Tricladida, Paludicola) from southern Brazil.
abstract: The karyotypes of four species of freshwater triclads of the genus Girardia (Platyhelminthes), i.e. G. schubarti, G. tigrina, G. anderlani, and G. biapertura, from populations of different localities of the Rio Grande do Sul State, in southern Brazil, were analyzed. The karyotype of G. biapertura is presented for the first time. Three basic complements of 4, 8, and 9 chromosomes were found. Diploids, triploids, or mixoploids (2n/3n) specimens were frequently detected in these populations. The basic chromosomal complement of n=9 was verified in two different species (G. biapertura and G. anderlani), presenting a large acrocentric chromosome which is rare in the family Dugesiidae. An intra and interspecific chromosomal variability was also detected and its evolutionary implications are discussed.
authors.affiliation: Programa de Pós-Graduação em Biologia, Instituto de Pesquisa de Planárias, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, Brazil.
authors.forename: E
authors.initials: E
authors.lastname: Benya
authors.forename: A M
authors.initials: AM
authors.lastname: Leal-Zanchet
authors.forename: W H
authors.initials: WH
authors.lastname: Santos
authors.forename: J
authors.initials: J
authors.lastname: Hauser
authors.forename: B
authors.initials: B
authors.lastname: Erdtmann
mesh_terms: D000818:Animals; D001938:Brazil; D002871:Chromosome Banding / Q000379:methods*; D002875:Chromosomes / Q000235:genetics*; D005618:Fresh Water; D010986:Platyhelminths / Q000235:genetics*; D011110:Polymorphism, Genetic