pedipalp
noun
ped·i·palp ˈpe-də-ˌpalp 
: either of the second pair of appendages of various arthropods (such as an arachnid or horseshoe crab) that lie on each side of the mouth and often perform a specialized function (such as grasping or feeling)
Note: Pedipalps are typically small and leglike in spiders, and large and pincerlike in scorpions.
Example Sentences
Recent Examples on the Web Some spiders even use part of the pedipalp, a bit just under the palpal bulb at the tip, to make music (stridulate) as part of a courtship ritual. 
Emily Willingham, Wired, 22 Sep. 2020 But as the male dismounts, the pedipalp grasps and twists the scapus, snipping it off as if with scissors. National Geographic, 14 Feb. 2017 Male orb weavers of the Argiope genus die upon inserting that second pedipalp. Liz Langley, National Geographic, 25 Feb. 2017
Emily Willingham, Wired, 22 Sep. 2020 But as the male dismounts, the pedipalp grasps and twists the scapus, snipping it off as if with scissors. National Geographic, 14 Feb. 2017 Male orb weavers of the Argiope genus die upon inserting that second pedipalp. Liz Langley, National Geographic, 25 Feb. 2017 Word History
Etymology
New Latin pedipalpus, from ped-, pes foot + palpus palpus
First Known Use
1826, in the meaning defined above