Mitochondrial genome heteroplasmy and phylogenomics of the stingless bee Tetragonula laeviceps (Apidae, Apinae, Meliponini)

Abstract

The heteroplasmic mitogenome of the stingless bee Tetragonula laeviceps from Peninsular Malaysia consists of two variants (TL1-1 and TL1-2), both with 29,084 bp consisting of two segments: the “canonical” segment contains 36 genes—13 protein-coding genes (PCGs), 2 rRNA, and 21 tRNA genes; and the inverted repeat segment consists of 31 genes (11 PCGs, 2 rRNAs, and 18 tRNAs). In the TL1-2 variant, the (nad4-nad4L-trnP-trnS1) gene segment in the “canonical” genome of the TL1-1 variant was inverted to (trnS1-trnP-nad4-nad4L). Phylogenetic analyses based on 13 PCGs and 15 mt-genes reveal that T. laeviceps from Peninsular Malaysia and China form a lineage in the subclade consisting also of the Tetragonula lineage of T. mellipes, T. davenporti, T. carbonaria, and T. hockingsi. The genetic distances of 13 PCGs and 15 mt-genes between T. laeviceps of Peninsular Malaysia and China (p = over 10%) and between the taxa of China (p = about or over 10%) indicate that these three taxa are genetically distinct, reflecting the presence of a species complex. The large genetic distances, based on COX1 sequences, of p = over 10% among the taxa of T. laeviceps of China, Peninsular Malaysia, Sabah, Indonesia, and India indicate beyond reasonable doubt that they are not conspecific. Assuming that the Peninsular Malaysian taxon is T. laeviceps s.str., the taxa of China, Sabah, Indonesia, and India (as well as Thailand based on the 16S rRNA gene) warrant to be accorded as distinct cryptic species. Likewise, the taxonomic status of some taxa (e.g., Tetragonula fuscobalteata of Sabah and Sulawesi) needs clarification.