Mitogenomes of understudied and misleading heterobranchs
we present the mitochondrial sequences of two opistobranch heterobranchs: Runcina aurata  and Facelina auriculata, the latter type taxon of the genus. The mitochondrial genomes were 14,282 and 14,171bp in length respectively, the two of them with a complete set of 13 CDS, 2 rRNAs, and 22 tRNAs. None of the mitogenomes showed gene reorganization, keeping the standard heterobranch mitogenomic structure. The base composition was completely distant between them, with a 25.7% GC for R. aurata, becoming the mitogenome with more AT content to the date, and 35% for F. auriculata, supposing one case of extremely rich GC content in opistobranch mitochondrial genomes.