SUPERFICIAL MANDIBULAR MUSCULATURE AND VOCAL SAC STRUCTURE IN HEMIPHRACTINE HYLID FROGS

Three patterns of superficial mandibular musculature are described in hemiphractine hylid frogs. One of these is unique to the morphological ly bizarre Hemiphractus. A second pattern is found in Flectonotus and also occurs in some species of Gastrotheca and Stefania. A third patte rn involves a differentiated apical element of the m, intermandibulari s and is found in Cryptobatrachus, many species of Gastrotheca, and on e species of Stefania. Evidence supports the plesiomorphic state of an undifferentiated m. intermandibularis and two derived states of diffe rentiation of that muscle. One of these is the development of suppleme ntary posterolateral elements characteristic of the Phyllomedusinae, w hereas the differentiation of an apical element has occurred in at lea st six independent lineages-the entire Pelodryadinae, three unrelated genera of Hylinae, and two genera of Hemiphractinae. Gastrotheca and S tefania are the only anuran genera known to include species possessing , and others lacking, differentiation of the m. intermandibularis. Voc al sacs and apertures are absent in Cryptobatrachus, Hemiphractus, Ste fania, and six species of Gastrotheca. (C) 1995 Wiley-Liss, Inc.