First report on chromosomes of Aeolosoma viride and Aeolosoma hemprichi (Aeolosomatidae; Annelida)

Aeolosomatidae are meiofaunal Annelida characterised by small size and almost exclusively asexual reproduction. This study is the first report on the chromosome morphology of two Aeolosomatidae species. Giemsa staining method and Propidium Iodide labelling were performed. The somatic chromosome number of Aeolosoma viride was 2n=30 with many metacentric elements. Decidedly different is A. hemprichi which shows ~70 small chromosomes with a dot like appearance. Chromosome repatternings such as Robertsonian fusions and pericentric inversions were suggested for the karyotype evolution of these species. The fixation of such repatternings is ensured by the clonal chromosome transmission in asexual reproduction.