Cytogenetics of the bathydraconid fish Gymnodraco acuticeps (Perciformes, Notothenioidei) from Terra Nova Bay, Ross Sea

In the framework of the I.C.E.FISH (International Collaborative Effort on A ntarctic Fish Adaptive Evolution) project, during the 1998-1999 season at t he Italian shore-based Terra Nova Bay Station, the broad fields of adaptati on and evolution of the fish suborder Notothenioidei were tackled through t he integration of many disciplines. As a representative contribution of I.C .E.FISH, a cytogenetic study of the bathydraconid fish Gymnodraco acuticeps is reported. The Bathydraconidae is a heterogeneous notothenioid taxon who se intra-family relationships are very uncertain. The conventional karyotyp e and the location of nuclear ribosomal genes, by means of fluorescence in situ hybridisation, contributed to species-specific characterisation and pr ovided the basis for comparative analyses. The karyotype of G. acuticeps co nsists of 48 chromosomes (2 metacentric, 2 submetacentric and 44 acrocentri c); major ribosomal cistrons correspond to a large region in a single chrom osome pair. Mapping of the available karyotypic data on a molecular phyloge netic tree provided information on chromosomal diversification during the c ladogenesis of the bathydraconids.