As with other flatworm mtDNAs, the nucleotide compositions of the new sequences are biased toward T and A, with T being the most favored nucleotide and C the least favored [46]. AT-richness in T. multiceps is 71.3% (24.4% A, 46.9% T, 20.3% G and 8.4% C), in T. hydatigena is 70.9% (24.9% A, 46.0% T, 20.3% G and 8.8% C) - the lowest for any taeniid studied to date - and in T. pisiformis 73.2% (27.7% A, 45.5% T, 18.0% G and 8.8% C), shown in Additional file 1. AT-bias in Taenia species is higher than amongst Echinococcus species, but not unusual amongst cestodes [49]. Amongst protein coding genes AT-content varies from 68.2 to 74.7%. Amongst Taenia species cytochrome c oxidase genes tend to have lower, or the lowest, AT-content [32,43] and long (LNR) and short non-coding regions (SNR) tend to have the highest AT-content (73.5-82.1%).