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Supernumerary tubercles rarely are present on the feet of Eleutherodactylus, but are present and numerous in every species of Syrrhophus, Tomodactylus, and in the members of the augusti group of Eleutherodactylus (Fig. 3). The tubercles are small and numerous in Syrrhophus and larger in Tomodactylus and the Eleutherodactylus augusti group. Most species of Eleutherodactylus have no plantar supernumerary tubercles; a few species have such tubercles, which never extend between the metatarsal tubercles as in Syrrhophus and Tomodactylus.

Fig. 3. Plantar views of feet of Eleutherodactylus alfredi (left, KU 93994, × 4.5), Syrrhophus pipilans nebulosus (middle, KU 58900, × 7.5), and Hylactophryne augusti (right, KU 102594, × 3) showing differences in size and arrangement of supernumerary tubercles.

Tarsal folds and tubercles are lacking in Syrrhophus, Tomodactylus, and the augusti group of Eleutherodactylus. Several species of Eleutherodactylus lack tarsal folds and tubercles, but in nearly every species group, one or more species possess either an inner tarsal fold, inner tarsal tubercle(s), or outer tarsal tubercles.

The terminal phalanges of Syrrhophus, Tomodactylus, and all Eleutherodactylus (except the frogs of the augusti group) are distinctly T-shaped. In the latter, the bones are knob-shaped distally (Fig. 4). T-shaped terminal phalanges also are present in Lithodytes and Trachyphrynus but not in other leptodactylid genera. At least one species of Eupsophus (E. quixensis) has terminal phalanges that resemble those of the Eleutherodactylus augusti group. Several species of Eleutherodactylus, Syrrhophus, and Tomodactylus with slender fingers have T-shaped terminal phalanges although the terminal dilations proportionately are only scarcely wider than the finger tips in the Eleutherodactylus augusti group. The presence of a terminal groove at the tip of the finger is an external indicator of the T-shaped terminal phalanges.

Fig. 4. Terminal phalanges of four leptodactylid frogs (all × 13.5). (a) Eleutherodactylus mexicanus, KU 55593; (b)