The "reciters" of the Majjhima Nikāya (q.v.), those who learned it and handed it down, probably the "school" of Sāriputta.
This "school" included the Cariyāpitaka, Apadāna and Buddhavamsa in the Khuddaka Nikāya, and ascribed the whole Nikāya to the Sutta Pitaka. DA.i.15; Mil.341.