Loxosceles vallenar, male left palp (MACN-Ar 44129) under scanning electron microscopy A prolateral B bulb, prolateral C detail of embolic keel D bulb, apical E bulb, dorsal F bulb, retrolateral. Arrows indicate embolic keel. Scale bars: 200 µm (A); 100 µm (B, E, F); 50 µm (C).