title: [Karyotypes, supernumerary chromosomes, rudimentary parthenogenesis and polyploidy in 2 species of the genus Phronima (Crustacea, Amphipoda)].
abstract: The diploid number of Phronima sedentaria and P. atlantica is 30, all the chromosomes are metacentric or submetacentric; the caryotypes of these two species are compared with those of other Amphipods. Some individuals of each species have a supernumerary chromosome. This element, found in both sexes, remains as an univalent at meiosis and goes earlier to one pole. In some cases nonfertilized ova undergo segmentation; this rudimentary parthenogenesis stops quickly and is partly related to polyploidization.
mesh_terms: D000782:Aneuploidy; D000818:Animals; D002875:Chromosomes; D003445:Crustacea / Q000502:physiology*; D005260:Female; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D010312:Parthenogenesis; D011123:Polyploidy
vernacular_title: Caryotypes, chromosomes surnuméraires, parthénogenèse rudimentaire et polyploidie chez deux espèces du genre Phronima (Crustaces, Amphipodes)