Maximum likelihood tree from concatenated dataset. Scale bar = 0.2 expected substitutions per position as estimated by RAxML. Stygoporus oregonensis in orange; other stygobitic dytiscids in blue; the epigean genus Sanfilippodytes, hypothesized by Larson and LaBonte (1994) to be the closest relative to S. oregonensis, in green. Bootstrap support given at nodes for Siettitiina and S. oregonensis + Ereboporus naturaconservatus.