A complete mitochondrial DNA genome of a mangrove clam <i>Geloina expansa</i> (Mousson, 1849)

The mangrove clam (Geloina expansa) is widely distributed in Asia, but its phylogenetic relationship to congeners (especially G. erosa) remains unclear. The complete mitochondrial genome of G. expansa was 15,187 bp and contained the typical 37 genes. Most protein-coding genes started with ATN and terminated with TAA or TAG. Some genes exhibited a different order from those in published Geloina mitogenomes, suggesting gene rearrangement. Phylogenetic analysis revealed that G. expansa clustered with one G. erosa mitogenome. Their small genetic distance (0.029) supports conspecificity, whereas another G. erosa individual showed a distance of 0.189, suggesting an unidentified species within Geloina.