_Description of tadpole._--The following description is based on KU 68556 from 7.5 kilometers south of Yetla, Oaxaca, Mexico (Figs. 4C and 6C). No limb buds; total length, 37.3 mm.; body length, 12.2 mm.; body length/total length, 32.7 per cent; body slightly depressed, barely wider than deep, ovoid in dorsal profile; mouth directed ventrally; eyes small, directed dorsolaterally; nostrils barely protuberant and directed anterolaterally, about midway between snout and eye; spiracle sinistral and posteroventrad to eye; anal tube dextral. Caudal fin low, bluntly rounded posteriorly; greatest depth of caudal musculature about one-half depth of caudal fin; musculature extends nearly to tip of tail. Mouth large; lips having deep lateral folds; two complete rows of papillae on lips; five to seven rows of papillae laterally; beaks moderately developed, bearing short peglike serrations; moderately wide lateral projections on upper beak; tooth-rows 4/6; upper rows subequal in length; fourth row interrupted medially; length of lower rows 1-4 equal to upper rows; fifth and sixth lower rows shorter; first lower row interrupted medially. Body brown above; tip of snout brown; venter creamy gray; caudal musculature creamy tan; caudal fin transparent; cream-colored crescent-shaped mark on posterior edge of body; dark brown flecks on caudal musculature and all except anterior two-thirds of ventral caudal fin; large brown square blotches on dorsum of caudal fin; eye reddish brown in life. _Variation._--The variation in size and proportions is given in Table 2. With the exception of one specimen having a short, broken, seventh tooth-row, all specimens have 4/6 tooth-rows that are like those described above. In some specimens the brown blotches on the dorsum of the caudal musculature are fused and marked with cream-colored flecks. _Comparisons._--_Ptychohyla leonhardschultzei_ differs from all other members of the _Ptychohyla euthysanota_ group in having a square snout, and further differs from _P. spinipollex_ in more numerous and smaller nuptial spines and in transverse, instead of posteromedially slanting, vomerine processes between the inner nares. _Ptychohyla leonhardschultzei_ differs from _P. euthysanota_ in having a rostral keel and in having white flanks boldly spotted with black. All small hylids that are sympatric with _Ptychohyla leonhardschultzei_ are either yellow (_Hyla dendroscarta_ and _H. melanomma_) or green (_Hyla erythromma_, which has a red eye, _Hyla hazelae_, which has a black line on the canthus, and _Ptychohyla ignicolor_, which has red flash colors on the thighs).