The features of external morphology that were studied in connection with the taxonomy of the genus Smilisca are discussed below.
The frogs of the genus Smilisca are medium to large tree frogs. The three species comprising the baudini group (S. baudini, cyanosticta, and phaeota) are notably larger than S. puma, sila, and sordida (Table 6). The largest specimen that we examined is a female of S. baudini having a snout-vent length of 90 mm. Smilisca puma is the smallest species; the largest male has a snout-vent length of 38 mm. and the largest female, 46 mm.
| Table 6.—Comparison of Sizes and Certain Proportions of the Species of Smilisca. (Means in Parentheses Below Observed Ranges; Data for Males Only.) | ||||
| Species | N | Snout-vent length | Tibia length/ snout-vent | Tympanum/ eye |
| S. baudini | 140 | 47.3-75.9 | 42.1-53.6 | 56.1-94.4 |
| (58.7) | (47.8) | (73.5) | ||
| S. cyanosticta | 40 | 44.6-56.8 | 51.9-59.7 | 62.7-88.4 |
| (50.7) | (56.0) | (71.4) | ||
| S. phaeota | 50 | 40.8-65.5 | 50.9-60.2 | 62.7-85.5 |
| (53.9) | (55.5) | (76.6) | ||
| S. puma | 20 | 31.9-38.1 | 48.2-53.1 | 52.1-72.2 |
| (34.7) | (51.3) | (64.9) | ||
| S. sila | 33 | 31.6-44.8 | 49.7-58.1 | 47.6-58.3 |
| (37.7) | (54.8) | (53.2) | ||
| S. sordida | 55 | 31.9-44.6 | 50.5-57.1 | 46.5-57.1 |
| (37.9) | (53.4) | (49.1) | ||
No outstanding differences in proportions exist between species, although certain proportions are sufficiently different in some species to warrant mention. Smilisca baudini is a more squat and stocky frog than other members of the genus; this is reflected in the somewhat shorter hind legs (Table 6). The size of the tympanum relative to that of the eye is highly variable within samples of a given species. Even so, noticeable differences in the tympanum/eye ratio are apparent. Members of the baudini group have the largest tympani, whereas S. sila and sordida have the smallest, and S. puma is intermediate (Table 6).
Although all members of the genus have rather truncate snouts, subtle differences exist among the species (Pl. 12). Smilisca sila has the shortest snout; that of S. baudini is only slightly longer. The snouts of S. cyanosticta and puma are nearly square in lateral profile, whereas those of S. phaeota and sordida are slightly inclined. The shape of the snout is relatively uniform within each species and displays no noticeable sexual dimorphism, except in S. sordida, in which there are sexual differences and geographic variation (see p. 324).
The characters of the hands and feet are among the most taxonomically important external features in Smilisca. Consistent differences exist in relative lengths of the digits, size of subarticular tubercles, size and number of supernumerary tubercles, size and shape of the inner metatarsal tubercle, and amount of webbing (Pls. 4 and 5). In the baudini group the series of species (baudini-phaeota-cyanosticta) show a progressive increase in amount of webbing in the hand and a decrease in number, and corresponding increase in size, of supernumerary tubercles. The amount of webbing in the feet of S. baudini and phaeota is about the same, but the webbing is slightly more extensive in S. cyanosticta. Smilisca puma is unique in the genus in lacking webbing in the hand; furthermore, this species is distinctive in having many large subarticular tubercles on the hand and a relatively small inner metatarsal tubercle. The two stream-inhabitants, S. sila and sordida, have shorter and stouter fingers than the other species. The webbing is most extensive in both the hands and feet of these species, which also are distinctive in having many small supernumerary tubercles on the feet.