Superficial mandibular musculature and vocal sac structure in the Anura

Abstract

A systematic survey has been undertaken of the superficial mandibular musculature, vocal sac structure and associated myointegumental lymphatic septa in nine anuran families. This study involved the examination, by microdissection, of ninety-five genera and three hundred and eighty-five species, so constituting approximately fifteen per cent. of the anuran fauna of the world. The rationale of the approach was that evolution of vocal sacs, intruding above the superficial mandibular muscles of male frogs, had introduced a new functional role for those muscles during distension of the sacs. In the absence of any direct contact between the superficial muscles and deeper structures, modification of the musculature was considered to be a reflection of the new functional requirements.