Anuptial pad (also known as thumb pad, or nuptial excrescence[1]) is a secondary sex characteristic present on some mature male frogs and salamanders.[2][3][4][5] Triggered by androgen hormones, this breeding gland (a type of mucous gland) appears as a spiked epithelial swelling on the forearm and prepollex that aids with grip, which is used primarily by males to grasp (or clasp) females during amplexus.[6] They can also be used in male–male combat in some species.[6]
Austrian biologist Paul Kammerer experimented on midwife toads' nuptial pads.[7] He used the offspring's apparent enlargening from generation-to-generation as evidence of Lamarckian evolution.[8]
Many amphibian species manifest nuptial pads for use in amplexus, an example being the rough-skinned newt, Taricha granulosa.[9]
