adjacent_to gena SIBO:0000090 Gena- Area of front of head bounded in front by the posterior margin of he clypeus, behind by the anterior margin of the eye, and medially by the antennal socket. The gena thus includes part of the cephalic dorsum and the side of the head capsule between the eye and the clypeus. (Bolton, B. (1994). Identificstion guide to the ant genera of the world. Cambridge, Mass., Harvard University PRess. pp.1-222). sibo head