Complete mitochondrial genome of the forensically important carrion beetle, Necrodes nigricornis (Coleoptera: Silphidae)

The carrion beetle, Necrodes nigricornis Harold, 1875 (Coleoptera: Silphidae) is one of the most frequently encountered insect species among Silphidae in animal cadavers in Korea. Consequently, the postmortem colonization of the species can provide useful information regarding the time-since-death. In this study, we report the mitochondrial genome (mitogenome) characteristics of N. nigricornis with the aim of increasing the genomic data pools of the family Silphidae, which is of considerable forensic importance. The full-length circular genome is 18,503 bp, with 75.60 % A/T content. It contains a typical set of 37 metazoan genes, but the non-coding A + Trich region is unusually long at 3,818 bp in length, containing two similar-sized repeats (539 and 542 bp) with a slight length and nucleotide variation. The gene arrangement of the species is identical to that of the ancestral arrangement found in the majority of insects. The biased A/T content in the genome is also reflected in the form of biased codon usage; six codons among 62 comprised solely of A/T nucleotides (TTA, ATT, TTT, ATA, TTA, and TAT) were highly used, accounting for 41.28 % of the total. The maximum-likelihood tree built using 12 PCG (excluding ND2) and lrRNA revealed monophyletic Silphidae, Silphinae, and Nicrophorinae, with relatively higher nodal supports (bootstrap support >= 80 %). N. nigricornis, belonging to Silphinae, was placed as the sister to congeneric N. littoralis with the highest nodal support. We believe this mitogenome sequences of the carrion beetle can become an important baseline information for future studies on phylogeny at various levels of taxonomic diversity, intra-specific variation, as well as species identification.