[Illustration: PLATE 13 Upper figure, _Hyla microcephala microcephala_ (KU 64593); middle figure, _H. microcephala underwoodi_ (KU 64565); lower figure, _H. microcephala underwoodi_ (UMMZ 115247). All approximately ×3.] [Illustration: PLATE 14 Upper figure, _Hyla robertmertensi_ (UMMZ 115243); middle figure, _H. phlebodes_ (KU 64798); lower figure, _H. sartori_ (UMMZ 119225). All approximately ×3.] [Illustration: PLATE 15 Tadpoles of _Hyla microcephala_ group: upper figure, _H. m. microcephala_ (KU 104097); lower figure, _H. phlebodes_ (KU 104099). Both ×4.] [Illustration: PLATE 16 Audiospectrograms and sections of mating calls of _Hyla microcephala_ group: (a) _H. m. microcephala_ (KU Tape No. 19); (b) _H. robertmertensi_ (KU Tape No. 41); (c) _H. phlebodes_ (KU Tape No. 6); (d) _H. sartori_ (KU Tape No. 190).] Table 4.--Comparative Cranial Osteology of Hyla microcephala Group ===============+=======================+========================+ Character | _H. microcephala_ | _H. robertmertensi_ | ---------------+-----------------------+------------------------+ Frontoparietal | Minimally ossified | Ossification extensive | | with large fontanelle | anteriorly with narrow | | extending from | medial separation; | | sphenethmoid to | fontanelle largest in | | occipital ridge. | parietal region. | | | | | | | Nasals | Moderately long and | Moderate in size; | | slender; arcuate in | slightly wider | | dorsal view. | anteriorly than | | | posteriorly in dorsal | | | view. | | | | Sphenethmoid | Extremely short in | Moderately short in | | dorsal view. | dorsal view. | | | | | | | | | | Columella | Distal and greatly | Distal and slightly | | expanded. | expanded or not. | ---------------+-----------------------+------------------------+ Table 4. (Continued) ===============+========================+======================== Character | _H. phlebodes_ | _H. sartori_ ---------------+------------------------+------------------------ Frontoparietal | Ossification extensive | Ossification moderately | anteriorly with narrow | extensive anteriorly; | medial separation; | medial separation of