Features of its morphology place it clearly within the bees , but it retains two unmodified ancestral traits of the legs which betray its origin . Derived features of its morphology ( `` apomorphies '' ) place it clearly within the bees , but it retains two unmodified ancestral traits ( `` plesiomorphies '' ) of the legs ( two mid-tibial spurs , and a slender hind basitarsus ) , indicative of its transitional status .