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 Antarctic Fish Adaptive Evolution) project, during the 1998–1999 season at the Italian shore-based Terra Nova Bay Station, the broad fields of adaptation and evolution of the fish suborder Notothenioidei were tackled through the 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 whose intra-family relationships are very uncertain. The conventional karyotype and the location of nuclear ribosomal genes, by means of fluorescence in situ hybridisation, contributed to species-specific characterisation and provided the basis for comparative analyses. The karyotype of G. acuticeps consists of 48 chromosomes (2 metacentric, 2 submetacentric and 44 acrocentric); major ribosomal cistrons correspond to a large region in a single chromosome pair. Mapping of the available karyotypic data on a molecular phylogenetic tree provided information on chromosomal diversification during the cladogenesis of the bathydraconids.