Erudition on Veneridae (Bivalvia: Heterodonta) through Cytogenetics - A Review

Veneridae, the heterodont bivalve family, comprises commercially valuable species. The economic significance of the family members has rendered them a subject of dispute among researchers. Relative to other bivalve families, the chromosomal features of Veneridae are poorly understood, with the predominant chromosome number being 2n = 38. This paper reviews studies on bivalve chromosomes to consolidate existing data and highlight recent advancements in the field, focusing on chromosome number, karyotypes, morphology, characteristics, ribosomal gene locations, histone genes, microsatellites, and telomeric sequences in Veneridae and briefly explains the fluorescence in situ hybridisation studies and chromosome manipulations. According to the data obtained for the current investigation, less than twenty species have karyological information available. 5S rDNA and 45S rDNA loci were delineated in ten species. Histone genes were delineated in eleven species. Telomeric sequences from eight vertebrate species were discovered. Microsatellites were identified in six species. Fluorescence in situ hybridisation (FISH) techniques were employed in over thirteen species. The restriction enzyme banding approach and polyploidization gained prominence. Chromosomal traits facilitate evolutionary research. Future studies must address chromosome morphology, sexual dimorphism in chromosomes, the organisation of histone genes (core histones and linker histone), satellite DNA, karyotype evolution, venerid chromosome anomalies, and cost-effective methods to ascertain ploidy levels.