Smilisca sordida, or the Drab Treefrog, is a small frog with the size varying from 36.2 mm for males to 56.3 mm for females
(Duellman 2001). The head is longer than it is wide. Individuals from the Caribbean lowlands have dull and round snouts, while those from the Pacific Lowlands have longer and more pointed snouts. Those observed from the Meseta Central have snout shapes in between those of the Caribbean and Pacific populations
(Duellman 2001). Eyes are moderately sized, and the distinct tympanum has a diameter of one-half the diameter of the eye
(Savage 2002). A supratympanic fold extends from behind the eye and over the tympanum, and is bordered by a dark line.
(Guyer and Donnelly 2005). The lips are slim and flared. The tongue is ovoid and somewhat notched posteriorly. Vomerine tooth patches are on elevated, almost transverse ridges between ovoid to elliptical choanae
(McCranie and Wilson 2002). The skin on the throat and chest is coarse and the skin on the belly and ventral surface of the thighs is roughly areolate.
(McCranie and Wilson 2002). Warts are present along the posteroventral border of the lower arm
(Savage 2002). The fingers are small and stout and finger discs are large. The fingers are one-half webbed and the toes are four-fifths webbed. Both fingers and toes have expanded discs
(Duellman 2001). The relative length of fingers is III>IV>II>I. Webbing is basal between fingers I-II, with the remaining webbing formula being
II 1-2 1/3 III 2--1 IV.
(McCranie and Wilson 2002).
The relative length of the toes is IV>III=V>II>I, with
the webbing formula for the feet being I 3 / 4-1-II 3 / 4-1 III 3 / 4-1 IV 1-3 / 4 V
(McCranie and Wilson 2002). The toe discs are broadly expanded and only slightly smaller than the toe discs on the fingers. The disc covers on the toes are even, and the disc pads on toes broadened. Lateral keels are present on the unwebbed portions of the toes
(McCranie and Wilson 2002). This species has an oval-shaped, flat, and elongated inner metatarsal tubercle.
Males have paired vocal slits and a light brown nonspinous nuptial pad on the base of each thumb
This frog has a gray-brown to tan dorsum, a white ventrum, and a deep purple groin. There is a poorly distinguished black mask around its eyes.
(Guyer and Donnelly 2005). Smilisca sordida has weak crossbands on its back legs, as well as dark spots on the head and back
(Leenders 2001). The posterior of the thigh is deep purple with small blue, green or tan flecks. Breeding males have a white vocal sac
(Duellman 2001). This species has a yellowish brown iris with black net-like veins
(Guyer and Donnelly 2005).
The larval body is moderately sized and reaches approximately 32 mm in length. The caudal musculature is beige with light red specks which vary from dark to light areas along the midline. The body is ovoid, the mouth ventral, and the nostrils and eyes are dorsolateral. The large, entire oral disc has well developed beaks with two-thirds denticle rows. The beaks are bluntly serrate and the papillae are in two rows which are sideways and ventral to the mouth. There are numerous extra rows at the corner of the mouth, but none higher than the mouth. The spiracle is lateral and sinistral. The vent tube is dextral. The tail is moderate in length and pointed, with moderately-sized caudal fins
The tadpole body is beige and the belly is pale beige with a silver or white tint. The iris is bronze (Savage 2002).
Smilisca sordida is easily confused with two other Smilisca species
(Guyer and Donnelly 2005). It is distinguished from Smilisca phaeota by the absence of a white stripe on its upper lip, and it does not have the spot beneath its eye that is characteristic of Smilisca baudinii
(Leenders 2001) . Duellman states that specimens taken from Honduras and Nicaragua are like those from the Meseta Central in Costa Rica, having bluish white mottling on the posterior flank and lacking light specks on the posterior surfaces of the thighs. These specimens are smaller and modestly different from those in the Pacific versant in Costa Rica, and indicate that the latter may represent a species different from Smilisca sordida
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Colombia, Costa Rica, Honduras, Nicaragua, Panama
In northwestern Costa Rica, Smilisca sordida is found in the subhumid Pacific slope gallery forests. From northeastern Honduras to northwestern Panama on the Atlantic slope, and in southwestern Costa Rica and neighboring western Panama and El Valle de Anton, Cocle Province, in west-central Panama, this species occurs in humid lowland and premontane forests. It can be found at up to 1,525 m in elevation
This frog lives near creeks and large rivers in riparian zones
(Guyer and Donnelly 2005). Smilisca sordida is most commonly found in humid areas in the vicinity of shallow, rocky streams which run through lowland moist and wet forests in the lowland dry forest area and in premontane moist and wet forests. They are also found in low vegetation, and hide in bromeliads when not in streams
Life History, Abundance, Activity, and Special Behaviors
This species is a common and nocturnal treefrog. Breeding occurs in the dry season, when the streams are shallow and clear. Males may call sporadically during the non-breeding season. Often, they will call in succession from a segment of the streambed on rocks or gravel bars
(Savage 2002). Their calls are characterized by pulsing, high-pitched notes, which rise in volume at the end. They may be in single or double pairs, and are often called in rapid succession for approximately 5-10 seconds, then followed by silence for a long period of time
(Guyer and Donnelly 2005). Females are stimulated by heavy rains to gather in large groups to breed. This may occur a few times at each site during the breeding seasons, depending on the number of rainy days. It is not known whether females lay more than one clutch per breeding season. Amplexus occurs near the shore or in the water. Oviposited eggs adhere to each other in masses of 20 to 50 eggs. The benthic larvae live in shallow, clear water where they use their large oral discs to clamp onto rocks to maintain stability
Malone (2004) observed that S. sordida constructs three different types of basins for egg deposition, in addition to laying eggs directly into streams or on substrate over streams. Eggs were either buried beneath substrate, deposited in an open basin with water, or deposited in an open basin with eggs attached to rocks or substrate at the bottom. While amplectant pairs dug to lay eggs beneath substrate, single males continuously attacked them to dislodge the male. Of the five pairs, one male was successfully dislodged. During digging, some females will use a dig/turn method where they will dig a depression, turn 45 to 90 degrees, then continued digging. This created an open basin with edges “delineated by small ramparts.” These different methods in egg deposition may be attempts at avoiding cannibalism of the eggs by conspecific tadpoles. At the beginning of the breeding season, tadpoles are scarce and thus females will lay eggs directly in the stream. However, towards the middle and end of the breeding season, eggs were deposited in basins, apparently due to higher tadpole densities in streams
Trends and Threats
This species does not appear to be threatened, and is common throughout its range. It can be found in urban areas and plantations and seems to do well even in disturbed habitat (IUCN 2006).
A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).
Duellman, W. E. (2001). The Hylid Frogs of Middle America. Society for the Study of Amphibians and Reptiles, Ithaca, New York.
Guyer, C., and Donnelly, M. A. (2005). Amphibians and Reptiles of La Selva, Costa Rica and the Caribbean Slope: A Comprehensive Guide. University of California Press, Berkeley.
IUCN, Conservation International, and Nature Serve. 2006. Global Amphibian Assessment: Smilisca sordida. www.globalamphibians.org. Accessed on 21 November 2007.
Leenders, T. (2001). A Guide to Amphibians And Reptiles of Costa Rica. Zona Tropical, Miami.
Malone, J. H. (2004). ''Reproduction in three species of Smilisca from Costa Rica.'' Journal of Herpetology, 38(1), 27-35.
McCranie, J. R., and Wilson, L. D. (2002). ''The Amphibians of Honduras.'' Contributions to Herpetology, Vol 19. K. Adler and T. D. Perry, eds., Society for the Study of Amphibians and Reptiles, Ithaca, New York.
Savage, J. M. (2002). The Amphibians and Reptiles of Costa Rica. University of Chicago Press, Chicago and London.
Written by Anna Doty (annad AT berkeley.edu), UC Berkeley
First submitted 2007-11-16
Edited by Kellie Whittaker (2009-11-02)
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