http://en.wikipedia.org/wiki/Taste This article on the human sense of taste is provided for reference.
The oral nerve plexus in amphioxus larvae ... (Goog)
"... a number of oral spines project across the mouth... The oral spine cells are secondary sense cells that synapse with neurites
belonging to a class of peripheral interneurons intrinsic to the oral nerve plexus. ... In comparative terms, the intrinsic neurons most closely resemble the Merkel-like accessory cells of vertebrate taste buds, and we postulate a homology between oral spine cells and taste buds despite differences in function."
Head Organization ... in Protochordates ... (Goog)
Fig. 3 Amphioxus visceral innervation. The top image is a cross section through the nerve cord. Cell bodies of the visceral motoneurons (solid) are ventral, with axons that project out the dorsal nerves. The somatic motoneurons lie just above these and innervate the myotome by means of axons confined within the cord itself. These synapse across the basal lamina, the postsynaptic targets being extensions from the cells of the myotome that cluster at this point. The lower image is a dorsal view of the cord showing how the visceral motoneurons are positioned near junctions between the somites (numbered), a pattern that continues caudally for tens of somites.