Description and Variation.—Considerable variation in size, and in certain proportions and structural characters was observed; variation in some characters seems to show geographic trends, whereas variation in other characters apparently is random. Noticeable variation is evident in coloration, but this will be discussed later.
In order to analyze geographic variation in size and proportions, ten adult males from each of 14 samples from various localities throughout the range of the species were measured. Snout-vent length, length of the tibia in relation to snout-vent length, and relative size of the tympanum to the eye are the only measurements and proportions that vary noticeably (Table 1). The largest specimens are from southern Sinaloa; individuals from the Atlantic lowlands of Alta Verapaz in Guatemala, Honduras, and Costa Rica are somewhat smaller, and most specimens from the Pacific lowlands of Central America are slightly smaller than those from the Atlantic lowlands. The smallest males are from the Atlantic lowlands of México, including Tamaulipas, Veracruz, the Yucatán Peninsula, and British Honduras.
| Table 1.—Geographic Variation in Size and Proportions in Males of Smilisca baudini. (Means in Parentheses Below Observed Ranges; Data Based on 10 Specimens From Each Locality.) | |||
| Locality | Snout-vent length | Tibia length/ snout-vent | Tympanum/ eye |
| Southern Sinaloa | 62.3-75.9 | 43.2-46.7 | 84.2-94.4 |
| (68.6) | (44.9) | (87.8 | |
| Ocotito, Guerrero | 55.6-64.0 | 46.1-51.2 | 66.7-82.8 |
| (58.7) | (47.8) | (74.6) | |
| Pochutla, Oaxaca | 56.1-65.1 | 44.7-49.4 | 73.0-84.2 |
| (60.2) | (47.5) | (77.4) | |
| San Salvador, El Salvador | 57.0-68.0 | 42.1-46.1 | 74.6-83.3 |
| (62.1) | (44.9) | (77.6) | |
| Managua, Nicaragua | 52.9-63.6 | 45.6-49.4 | 73.7-89.7 |
| (57.3) | (47.5) | (79.4) | |
| Esparta, Costa Rica | 57.6-66.0 | 44.6-49.3 | 65.5-83.6 |
| (61.3) | (47.3) | (75.2) | |
| Ciudad Victoria, Tamaulipas | 50.6-56.9 | 44.5-48.7 | 67.2-84.3 |
| (53.7) | (46.6) | (73.9) | |
| Córdoba, Veracruz | 53.8-63.4 | 43.9-48.4 | 66.1-75.9 |
| (57.5) | (45.6) | (70.0) | |
| Isla del Carmen, Campeche | 47.3-56.6 | 44.7-48.9 | 61.5-72.6 |
| (50.9) | (47.6) | (65.7) | |
| Chichén-Itzá, Yucatán | 49.6-57.1 | 45.2-53.4 | 62.7-80.7 |
| (53.8) | (49.5) | (72.6) | |
| British Honduras | 49.0-59.6 | 47.5-50.7 | 67.9-76.8 |
| (54.9) | (49.1) | (72.2) | |
| Chinajá, Guatemala | 56.8-67.6 | 47.0-51.0 | 70.0-82. |
| (63.2) | (49.5) | (73.6 | |
| Atlantidad, Honduras | 52.5-65.1 | 49.8-53.6 | 56.1-76.5 |
| (57.6) | (51.5) | (67.0) | |
| Limón, Costa Rica | 57.7-71.3 | 50.4-52.3 | 63.9-73.0 |
| (62.4) | (51.2) | (68.5) | |
The ratio of the tibia to the snout-vent length varies from 42.1 to 53.6 in the 14 samples analyzed. The average ratio in samples from the Pacific lowlands varies from 44.9 in Sinaloa and El Salvador to 47.8 in Guerrero; on the Gulf lowlands of México the average ratio varies from 45.6 in Veracruz to 47.6 on Isla del Carmen, Campeche. Specimens from the Yucatán Peninsula and the Caribbean lowlands have relatively longer legs; the variation in average ratios ranges from 49.1 in British Honduras to 51.2 in Costa Rica and 51.5 in Honduras.
Specimens from southern Sinaloa are outstanding in the large size of the tympanum; the tympanum/eye ratio varies from 84.2 to 94.4 (average 87.8). In most other samples the variation in average ratios ranges from 72.2 to 79.3, but specimens from Veracruz have an average ratio of 70.0; Campeche, 65.7; Honduras, 67.0; and Limón, Costa Rica, 68.5.
No noticeable geographic trends in size and proportions are evident. Specimens from southern Sinaloa are extreme in their large size, relatively short tibia, and large tympani, but in size and relative length of the tibia the Sinaloan frogs are approached by specimens from such far-removed localities as San Salvador, El Salvador, and Chinajá, Guatemala. Frogs from the Caribbean lowlands of Honduras and Costa Rica are relatively large and have relatively long tibiae and small tympani.
The inner metatarsal tubercle is large and high and its shape varies. The tubercle is most pronounced in specimens from northwestern México, Tamaulipas, and the Pacific lowlands of Central America. Possibly the large tubercle is associated with drier habitats, where perhaps the frogs use the tubercles for digging.
The ground color of Smilisca baudini is pale green to brown dorsally and white to creamy yellow ventrally. The dorsum is variously marked with dark brown or dark olive-green spots or blotches (Pl. 6A). In most specimens a dark interorbital bar extends across the head to the lateral edges of the eyelid; usually this bar is connected medially to a large dorsal blotch. There is no tendency for the markings on the dorsum to form transverse bands or longitudinal bars. In specimens from the southern part of the range the dorsal dark markings are often fragmented into small spots, especially posteriorly. The limbs are marked by dark transverse bands, usually three on the forearm, three on the thigh, and three or four on the shank. Transverse bands also are present on the tarsi and proximal segments of the fingers and toes. The webbing on the hands and feet is pale grayish brown. The loreal region and upper lip are pale green or tan; the lip usually is boldly marked with broad vertical dark brown bars, especially evident is the bar beneath the eye. A dark brown or black mark extends from the tympanum to a point above the insertion of the forearm; in some specimens this black mark is narrow or indistinct, but in most individuals it is quite evident. The flanks are pale gray to creamy white with brown or black mottling, which sometimes forms reticulations enclosing white spots. The anterior surfaces of the thighs usually are creamy white with brown mottling, whereas the posterior surfaces of the thighs usually are brown with small cream-colored flecks. A distinct creamy white anal stripe usually is present. Usually, there are no white stripes on the outer edges of the tarsi and forearms. In breeding males the throat is gray.
Most variation in coloration does not seem to be correlated with geography. The lips are strongly barred in specimens from throughout the range of the species, except that in some specimens from southern Nicaragua and Costa Rica the lips are pale and in some specimens the vertical bars are indistinct. Six specimens from 7.3 kilometers southwest of Matatán, Sinaloa, are distinctively marked. The dorsum is uniformly grayish green with the only dorsal marks being on the tarsi; canthal and post-tympanic dark marks absent. A broad white labial stripe is present and interrupted by a single vertical dark mark below the eye. A white stripe is present on the outer edge of the foot. The flanks and posterior surfaces of the thighs are creamy white, boldly marked with black. Two specimens from Alta Verapaz, Guatemala (CNHM 21006 from Cobán and UMMZ 90908 from Finca Canihor), are distinctive in having many narrow transverse bands on the limbs and fine reticulations on the flanks. Two specimens from Limón Province, Costa Rica (KU 34927 from Batán and 36789 from Suretka), lack a dorsal pattern; instead these specimens are nearly uniform brown above and have only a few small dark brown spots on the back and lack transverse bands on the limbs. The post-tympanic dark marks and dark mottling on the flanks are absent. Specimens lacking the usual dorsal markings are known from scattered localities on the Caribbean lowlands from Guatemala to Costa Rica.