A circular map of the complete mitochondrial genome of the sea spider Achelia bituberculata (Family Ammotheidae). Protein and rRNA genes are abbreviated as follows: atp6 and atp8 (genes for ATPase subunits 6 and 8), cox1-cox3 (genes for cytochrome C oxidase subunits I-III), cob (gene for apocytochrome b), nad1-nad6 and nad4L (genes for NADH dehydrogenase subunits 1–6 and 4L), and rrnS and rrnL (genes for 12S and 16S rRNAs). All the 22 tRNA genes are located among protein- and/or tRNA-coding genes. The tRNA genes are named using single-letter amino acid abbreviations, with the exception of those coding for leucine and serine, which are named L 1 for the tRNALeu(UUR) (anticodon TAA) gene, L 2 for the tRNALeu(CUN) (anticodon TAG) gene, S 1 for the tRNASer(UCN) (anticodon TGA) gene and S 2 for the tRNASer(AGN) (anticodon GCT) gene. The arrows indicate the orientations of the gene components.