Unusual mitochondrial tRNA rearrangements in stingless bee Tetragonula pagdeni and phylogenetic analysis

Tetragonula pagdeni (Hymenoptera: Meliponini) is a widely distributed and economically important stingless bee. The taxonomic status and evolution of this species have not been fully understood. We sequenced the mitogenome of T. pagdeni and analyzed its characteristics including gene rearrangements in present work, which will provide help for better protection and utilization of this germplasm resource. The mitochondrial genome sequence was obtained by establishing library and high-throughput sequencing. Using all protein coding sequences joined, the phylogenetic analysis demonstrated that T. pagdeni has the closest kinship with Lepidotrigona species, and then has a second closest kinship with the Melipona stingless bees. All the stingless bee species (Meliponini) analyzed formed a single clade, and among them the T. pagdeni mitogenome exhibited the highest gene rearrangement score, suggesting this species has an overactive evolutionary history. Especially, an unusual tRNA-Gly translocation was observed in T. pagdeni mitogenome, which broke the super-conserved atp8-atp6-cox3-G block in Hymenoptera mitogenomes. The translocated tRNA-Gly moved to a position next to the D-loop control region, and whether this translocation has a functional effect to the widely distributed T. pagdeni need further exploration. The variations of gene positions in mitogenome could also provide useful information to clarify the phylogenetic relations in Meliponini.