The two palpal bulbs – also known as palpal organs and genital bulbs – are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps, giving the spider an appearance
Male Cheiracanthium mildei showing the enlarged and darker palpal bulbs at the end of the pedipalps
Left palpal bulb of a male Thaida chepu: 1 – from the right (prolateral side nearest the mouth); 2 – from the ventral side, i.e. underside; 3 – from the left (retrolateral side, furthest from the mouth) bH – basal haematodocha; Cb – cymbium; E – embolus; HSt – hook of subtegulum; mA – median apophysis; mH – median haematodocha; PSt – process of subtegulum; St – subtegulum; Te – tegulum See text for further explanation.