The buccal membranelles are entirely situated in the buccal cavity and constitute the posterior portion of the oral primordium in early dividers. Note that some authors do not differentiate between elongated collar membranelles and buccal membranelles, but lump them to infundibular membranelles/polykinetids (e.g., Wasik and Mikoajczyk 1994). The term “buccal membranelles” is preferred instead of “internal membranelles” (Petz et al. 1995), as it clearly describes the position of the membranelles in the buccal cavity and is also applicable for the small membranelles in the Halteriida and Oligotrichida. Agatha and Riedel-Lorjé (2006)