Mitochondrial Genome Sequences of Spirometra erinaceieuropaei and S. decipiens (Cestoidea: Diphyllobothriidae).

The present study was performed to compare the mitochondrial genomes between 2 Spirometra tapeworms, Spirometra erinaceieuropaei and Spirometra decipiens (Cestoidea: Diphyllobothriidae), which larval stages are important etiological agents of sparganosis in humans. For each species, the full mitochondrial genome was amplified in 8 overlapping fragments using total genomic DNA purified from a single worm as the template. The mitochondrial genomes were 13,643 bp (S. erinaceieuropaei) and 13,641 bp (S. decipiens) in length and contained 36 genes; 12 protein-coding genes, 2 ribosomal RNA (rRNA, small and large subunits), and 22 transfer RNAs (tRNAs). The 12 protein-coding genes constituted 10,083 bp (S. erinaceieuropaei) and 10,086 bp (S. decipiens) of their respective mitochondrial genomes. The tRNA genes, ranging in length from 56 to 70 bp, were identified based on putative secondary structures such as the typical cloverleaf shape. A total of 23 intergenic sequences, varying from 1 to 204 bp in size, were interspersed in S. erinaceieuropaei (total, 504 bp) and S. decipiens (total, 496 bp) mtDNA. The 12 protein-coding genes of S. erinaceieuropaei and S. decipiens differed by 12.4%, whereas the overall difference in mtDNA sequence between S. erinaceieuropaei and S. decipiens was 12.9%. Thus, from the standpoint of the mitochondrial genome, S. decipiens represents a valid species that can be distinguished from S. erinaceieuropaei.