2021 Volume 86 Issue 2 Pages 175-179
Karyotypes, C-banded heterochromatin, and silver-positive nucleolus organizer regions (Ag-NORs) of two anemonefish species, Amphiprion polymnus and Premnas biaculeatus, were studied and compared with those of previously reported species, A. clarkii, A. frenatus, and A. perideraion. The chromosome number was 2n=48 for all five species. The fundamental numbers (NF) in A. polymnus (NF=84) and P. biaculeatus (NF=90) were different from the three species (NF=86). Karyotypic differences among the species were found in the distribution of C-banded heterochromatin for large submetacentric chromosomes. Moreover, A. polymnus showed a peculiar C-banding pattern with telomeric C-bands distributed in all chromosomes. The Ag-NORs were commonly located in the terminal regions of the short arms of an acrocentric pair; however, the NOR-bearing chromosomes were different in size among the species. This study demonstrated that the karyotypes of A. polymnus and P. biaculeatus had different conditions from those of the three previously studied species and that the C-band patterns in large submetacentric chromosomes could be a potential reliable marker to distinguish the anemonefish.