O. variabilis is most similar to
O. simulans and
O. cornuta, but it can be distinguished from them by the form of the head. In both
O. simulans and
O. cornuta the head is most often moderately bituberculate; in
O. variabilis the head is not bituberculate.
(1)
In most spmns of
O. simulans the third antennal segment is clearly shorter than is the fourth, but in
O. variabilis the third segment is nearly the same length as the fourth antennal segment.
(1)