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Family Genus Specific epithet Specific authority Infraspecific category
2C mean1(pg) 2C mean1(mbp) 2C range1 pg
Chromosome number (2n) Ploidy level
Number of 5S signals Range of 5S signals Position2 of 5S signals (5S P)
Number of 45S3 signals Range of 45S signals Position2 of 45S signals (45S P) Arrangement
Autosome or sex chromosome 5S chrom. type
Sex chrom. number 45S chrom. type
B chromosomes Ag-NOR
Original reference

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Family   Genus   Specific epithet
Chromosome number from: -   Ploidy level from: -

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1 source: Animal genome size database (
2 position refers to interstitial, pericentromeric, distal or occupying whole chromosome arm
3 refers to 45S rDNA (18S-5.8S-26S rRNA genes)

Welcome to the animal rDNA database (Release 2.0)!

Ribosomal DNA loci encoding ribosomal RNA genes (rDNA) are important components of chromosomes. Their number and positions on chromosomes are important characteristics of karyotypes. Information is used in a wide range of biological fields including evolutionary biology, phylogenetics, systematics or animal breeding.

The animal rDNA database provides currently information on number and position of rDNA loci for 2800 animal species from 340 families.

The data of this second release comes from 1040 papers based on in situ hybridization of 5S and 45S rDNA, published until March 2021. You can also find several new features in advanced search, such as type of the chromosome bearing rDNA (autosome, sex chromosome, B chromosome) or the number of Ag-NORs reflecting activity of rDNA loci.

We thank the authors of publications for providing source data. Any corrections, suggestions for improvement or new information are wellcomed. These should be addressed to: and

(*) Fluorescent in situ hybridisation


NOTE: The database is not providing any rDNA sequence, only information about rDNA site number and position in chromosomes. If you are interested in sequence data, you can consult other databases listed here.

Animal rDNA Database