Agalychnis callidryas, the red-eyed tree frog, is a slender, colorful, medium-sized frog. Females measure up to 77 mm, and males to 59 mm (Savage 2002). This frog has leaf-green to dark green dorsal surfaces; dark blue, purple, or brownish flanks, with cream-colored or yellow vertical or diagonal bars; blue or orange upper arms; thighs that are blue or orange on the anterior, posterior, and ventral surfaces; orange hands and feet, except for the outermost digits on each; a white ventrum; and protuberant red eyes, with vertical pupils (Savage 2002; Leenders 2001; Duellman 2001). The back is sometimes marked with faint tranverse darker green lines (especially in individuals from Nicaragua or Costa Rica) or small white dots (Duellman 2001). The average number of bars on the flanks increases in populations from north to south, with a mean of 5.0 bars in Mexico and a mean of 9.0 bars in Panama (Duellman 2001). In some populations from the middle part of the range (Nicaragua and Costa Rica, on the Caribbean side), there is often a continuous, longitudinal yellowish stripe connecting the upper ends of the vertical bars and separating the blue flanks from the green dorsum (Duellman 2001).
The skin is smooth both dorsally and ventrally (Savage 2002). Agalychnis callidryas has a rounded head and a truncated snout when viewed from above (Duellman 2001). Eyes are large and directed sideways (Leenders 2001). When this frog closes its eyes, transparent lower eyelids marked with a network of gold are apparent (Leenders 2001). It has distinct tympana (Savage 2002). The body is slender and somewhat flattened (Leenders 2001). Fingers are short, about one-half webbed, and have moderately large discs (Duellman 2001). The toes are short, about two-thirds webbed, and also have moderately large discs that are nearly as large as those on the fingers, with a narrow fold running from the heel to the disc of the fifth toe (Duellman 2001; Savage 2002). Adult males have paired vocal slits and a single internal median subgular vocal sac, as well as a grayish brown spinose nuptial pad at the base of each thumb (Savage 2002).
Young froglets (at least from Panama) are able to change color; they are green by day and change to purplish or reddish brown at night (Pyburn 1963). In addition, young froglets have yellow rather than red eyes, and have lighter-colored flanks lacking whitish bars (Pyburn 1963). The red eye coloration appears first at the periphery of the eye at about two weeks post-metamorphosis, and over a period of several days spreads inward to make the iris wholly red (Starrett 1960).
Agalychnis callidryas tadpoles are large, with a robust body that can measure 48 mm in total length at stage 34 (Savage 2002). The tail and caudal fins are moderately sized, with the tail tip narrowing to a thin flagellum (Savage 2002). The spiracle is sinistral and lateroventral, while the vent is dextral (Savage 2002). Eyes and nostrils are dorsolateral (Savage 2002). The mouth is anteroventral, with a small and complete oral disk, serrated beaks, and two upper plus three lower rows of denticles (Savage 2002; Duellman 2001). The row of denticles just above the mouth has a small gap medially (Savage 2002). Labial papillae are present on the lower lip in one to three rows lateral and ventral to the mouth, and on the upper lip in one to two rows lateral to the mouth, but lacking directly above the mouth (Duellman 2001). The tadpole body is olive gray dorsally, shading into a bluish gray speckled with olive-brown on the sides and undersides (Duellman 2001). Larval caudal musculature is a light grayish brown while the caudal fins are transparent, but both are speckled with dark gray (Duellman 2001).
The diploid number of chromosomes is 26 for Agalychnis callidryas (Duellman and Cole 1965).
A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).
- Ruiz-Carranza, P.M., Ardila-Robayo, M.C., and Lynch, J.D (1996). ''Lista actualizada de la fauna de Amphibia de Colombia.'' Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 20(77), 365-415.
- Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., and Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
- Duellman, W. E. (2001). The Hylid Frogs of Middle America. 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.
- Briggs, V. S. (2008). ''Mating patterns of red-eyed treefrogs, Agalychnis callidryas and A. moreletii.'' Ethology, 114, 489-498.
- Caldwell, M. S., Johnston, G. R., McDaniel, J. G., and Warkentin, K. M. (2010). ''Vibrational signaling in the agonistic interactions of red-eyed treefrogs.'' Current Biology, doi:10.1016/j.cub.2010.03.069.
- Cope, E. D. (1862). ''Catalogue of the reptiles obtained during the explorations of the Parana, Paraguay, Vermejo, and Uruguay Rivers, by Captain Thos. J. Page, U.S.N., and of those procured by Lieut. N. Michler, U.S. Top. Eng., Commander of the expedition conducting the survey.'' Proceedings of the Academy of Natural Sciences of Philadelphia, 14, 346-359.
- D'Orgeix, C. A., and Turner, B. J. (1995). ''Multiple paternity in the red-eyed treefrog Agalychnis callidryas (Cope).'' Molecular Ecology, 4, 505-508.
- Donnelly, M., and Guyer, C. (1994). ''Patterns of reproduction and habitat use in an assemblage of Neotropical hylid frogs.'' Oecologia, 98, 291-302.
- Dudley, R., King, V. A., and Wassersug, R. J. (1991). ''The implications of shape and metamorphosis for drag forces on a generalized pond tadpole (Rana catesbeiana).'' Copeia, 1991, 252-257.
- Duellman, W. E. (1967). ''Courtship isolating mechanisms in Costa Rican hylid frogs.'' Herpetologica, 23(3), 169-183.
- Duellman, W. E. (1963). ''Amphibians and reptiles of the rainforest of southern El Petén, Guatemala.'' University of Kansas Publications, Museum of Natural History, 15, 205-249.
- Duellman, W. E., and Cole, C. J. (1965). ''Studies of chromosomes of some anuran amphibians.'' Systematic Zoology, 14(2), 139-143.
- Fouquette, M. J., Jr. (1968). ''Some hylid frogs of the Canal Zone, with special reference to call structure.'' Caribbean Journal of Science, 6(3-4), 167-172.
- Gray, L. A., and Nishikawa, K.C. (1995). ''Feeding kinematics of phyllomedusine tree frogs.'' The Journal of Experimental Biology, 198, 457-463.
- Gray, L. A., and Rand, A. S. (1997). ''A daybreak chorus in the frog, Agalychnis callidryas.'' Journal of Herpetology, 31(3), 440-441.
- Leenders, T. (2001). A Guide to Amphibians And Reptiles of Costa Rica. Zona Tropical, Miami.
- McCranie, J. R., Wilson, L. D., and Townsend, J. H. (2003). ''Agalychnis callidryas (Red-eyed Treefrog). Reproduction.'' Herpetological Review, 34(1), 43.
- Mignogna, G., Severina, C., Erspamer, G. F., Siciliano, R., Kreil, G., and Barra, D. (1997). ''Tachykinins and other biologically active peptides from the skin of the Costa Rican phyllomedusid frog Agalychnis callidryas.'' Peptides, 18(3), 367-372.
- Pyburn, W. F. (1963). ''Observations on the life history of the treefrog, Phyllomedusa callidryas (Cope).'' Texas Journal of Science, 15, 155-170.
- Pyburn, W. F. (1964). ''Breeding behavior of the leaf-frog, Phyllomedusa callidryas, in southern Veracruz.'' The American Philosophical Society Yearbook, 1964, 291-294.
- Pyburn, W. F. (1970). ''Breeding behavior of the leaf-frogs Phyllomedusa callidryas and Phyllomedusa dacnicolor in Mexico.'' Copeia, 2, 209-218.
- Roberts, W. E. (1994). ''Explosive breeding aggregations and parachuting in a neotropical frog, Agalychnis saltator (Hylidae).'' Journal of Herpetology, 28(2), 193-199.
- Shi, Y-B. (2000). Amphibian Metamorphosis: From Morphology to Molecular Biology. Wiley-Liss, Inc., New York.
- Starrett, P. (1960). ''Descriptions of tadpoles of Middle American frogs.'' Miscellaneous Publications Museum of Zoology, University of Michigan, 110, 5-37.
- Valerio, C.E. (1971). ''Ability of some tropical tadpoles to survive without water.'' Copeia, 1971(2), 364-365.
- Vonesh, J. R., and Warkentin, K. M. (2006). ''Opposite shifts in size at metamorphosis in response to larval and metamorph predators.'' Ecology, 87(3), 556-562.
- Warkentin, K. M. (1995). ''Adaptive plasticity in hatching age: A response to predation risk trade-offs.'' Proceedings of the National Academy of Sciences, 92, 3507-3510.
- Warkentin, K. M. (2000). ''Environmental and developmental effects on external gill loss in the Red-Eyed Tree Frog, Agalychnis callidryas.'' Physiological and Biochemical Zoology, 73(5), 557-565.
- Warkentin, K. M. (2000). ''Wasp predation and wasp-induced hatching of red-eyed treefrog eggs.'' Animal Behavior, 60, 503-510.
- Warkentin, K. M. (2002). ''Hatching timing, O2 availability and external gill regression in the treefrog, Agalychnis callidryas.'' Physiological and Biochemical Zoology, 75, 155-164.
- Warkentin, K. M. (2005). ''How do embryos assess risk? Vibrational cues in predator-induced hatching of red-eyed treefrogs.'' Animal Behavior, 70, 59-71.
- Warkentin, K. M., Buckley, C. R., and Metcalf, K. A. (2006). ''Development of red-eyed treefrog eggs affects efficiency and choices of egg-foraging wasps.'' Animal Behavior, 71, 417-425.
- Warkentin, K. M., Caldwell, M. S., Siok, T. D., D'Amato, A. T., and McDaniel, J. G. (2007). ''Flexible information sampling in vibrational assessment of predation risk by red-eyed treefrog embryos.'' The Journal of Experimental Biology, 210, 614-619.
- Warkentin, K. M., Caldwell, M. S., and McDaniel, J. G. (2006). ''Temporal pattern cues in vibrational risk assessment by embryos of the red-eyed treefrog, Agalychnis callidryas.'' Journal of Experimental Biology, 209, 1376-1384.
- Warkentin, K. M., Currie, C. R., and Rehner, S. A. (2001). ''Egg-killing fungus induces early hatching of red-eyed treefrog eggs.'' Ecology, 82(10), 2860-2869.
- Warkentin, K. M., and Wassersug, R. J. (2001). ''Do prostaglandins regulate external gill regression in anurans?'' Journal of Experimental Zoology, 289, 366-373.