Complete mitochondrial genomes of two deep-sea pandalid shrimps, Heterocarpus ensifer and Bitias brevis: insights into the phylogenetic position of Pandalidae (Decapoda: Caridea)

The mitochondrial genome (mitogenome) analysis is a significant tool for investigating the evolutionary history of metazoan animals. The family Pandalidae is a diverse caridean group containing mainly deep-sea species. Until May 30 2019, only two complete mitogenomes are available in GenBank. Here we present the complete mitogenome sequences of two deep-sea pandalid shrimps, Heterocarpus ensifer and Bitias brevis through Illumina sequencing. The mitochondrial genomes were determined to be 15 939 bp and 15 891 bp long, and both consist of 13 protein-coding genes (PCGs), 23 transfer-RNA genes (tRNAs), two ribosomal-RNA genes (rRNAs), and one control region. The nucleotide composition is biased toward adenine and thymine. Overall, the gene contents and arrangements are consistent with the pancrustacean ground pattern. The alignment of the control regions of four pandalids reveals a conserved sequence block (CSB) (104 bp in length, average GC%=29.47% and 69.23% similarity). A phylogenetic analysis based on 51 Caridea complete mitogenomes revealed that the deep-sea pandalid shrimps are situated an intermediate lineage, with a tendency to originated from those living in shallow sea area.