The chromosome complement of two parthenogenetic Ostracodan species is described, that is Eucypris virens (Jurine) and Cypris bispinosa Lucas. The karyotype of E. virens (12 chromosomes in the somatic cells) consists of two metacentric chromosomes of very different length, one submetacentric, one subtelocentric and eight acrocentric. No chromosome pairs can be suggested according to the length and the centromeric position. The karyotype of C. bispinosa consists, in the somatic cells, of 22 chromosomes, all acrocentric, which can be arranged in pairs according to the length, except two. The chromosome complement of this species appears, therefore, clearly diploid, while in E. virens the diploid character is lost, the two chromosome sets having become almost completely unlike. This would suggest that the apomictic parthenogenesis is developed much earlier in E. virens
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M. J. D. WHITE,
Animal Cytology and Evolution, 2nd. Ed.,
Cambridge Univ. Press, Cambridge (
1954). |
fulltext (doi) |
MR 2358923
Con il contributo del Ministero per i Beni e le Attività Culturali