Comparison of Mitochondrial Genome Sequences between Two Palaemon Species of the Family Palaemonidae (Decapoda: Caridea): Gene Rearrangement and Phylogenetic Implications

To further understand the origin and evolution of Palaemonidae (Decapoda: Caridea), we determined the mitochondrial genome sequence of Palaemon macrodactylus and Palaemon tenuidactylus. The entire mitochondrial genome sequences of these two Palaemon species encompassed 37 typical genes, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs), and a control region (CR). The lengths of their mitochondrial genomes were 15,744 bp (P. macrodactylus) and 15,735 bp (P. tenuidactylus), respectively. We analyzed their genomic features and structural functions. In comparison with the ancestral Decapoda, these two newly sequenced Palaemon species exhibited a translocation event, where the gene order was trnK-trnD instead of trnD-trnK. Based on phylogenetic analysis constructed from 13 PCGs, the 12 families from Caridea can be divided into four major clades. Furthermore, it was revealed that Alpheidae and Palaemonidae formed sister groups, supporting the monophyly of various families within Caridea. These findings highlight the significant gene rearrangements within Palaemonidae and provide valuable evidence for the phylogenetic relationships within Caridea.