What are the paired sensory appendages projecting from the base of the proboscis called?

The paired sensory appendages projecting from the base of the proboscis are referred to as palpi. Palpi are typically involved in sensory functions, often aiding in taste, smell, or touch. In many organisms, particularly arthropods, palpi serve as important appendages that assist in the perception of environmental stimuli.

Antennules, while also sensory structures, are typically shorter and located on the cephalothorax in crustaceans and other arthropods. Mandibles are primarily used for feeding and manipulating food rather than serving a sensory function. Maxillae, similar to mandibles, are also involved primarily in feeding processes, and although they may have some sensory capabilities, their main role is not primarily sensory like that of the palpi. Thus, the palpi are the correct term for the paired sensory appendages associated with the proboscis.