Description
Agalychnis annae is a moderately large and slender frog. Males have a maximum snout-vent length of 73.9 mm, and females 84.2 mm. The head is slightly convex and is narrower than the body. Males have a softly sloping snout from the eyes to the nostrils in lateral profile. Females have a blunt snout in lateral profile (Duellman 2001). The eyes are large and the lower eyelid is reticulate. The dorsal surface is smooth and the venter is faintly granulate (Savage 2002). The tympanum is distinct, besides the upper and posterior edges which are covered by a heavy dermal fold. This fold extends from the posterior corner of the orbit to a point posterior to the angle of the jaw. A narrow dermal fold also extends from the elbow along the ventrolateral edge of the forearm onto the base of the fourth finger. A weak tarsal fold is observed along the entire length of the tarsus. Another thin dermal fold is present from the heel along the ventrolateral edge of the tarsus to the fifth toe. The upper arm is slim and the forearm robust, while the hind limb is slender. The fingers of A. annae are short with large discs. The diameter of the disc on the third finger is equal to that of the tympanum. The toes are somewhat slim and the terminal discs are only slightly smaller than those on the hand. Fingers are about 2/3 webbed and toes are about ¾ webbed (Duellman 2001). The webbing formula for the fingers is: I 2-2½; II 1½-3- III 2-2 IV. The webbing formula for the toes is: I 2-2+ II 1½-3 III 1½-2½ IV 2+ -1½ V. There is a brown nuptial pad on the base of the thumb in adult males (Savage 2002). The vocal sac is unpaired, median, subgular and not markedly distensible (Duellman 2001).

This frog is quite colorful. In contrast to the uniform green upper surfaces, the proximal dorsal portion of the upper arm is pink to lavender and the distal portion is blue. The flanks and anterior and posterior thigh surfaces are blue. The upper surface of the hands and feet are green, orange, and blue. There are vivid creamy yellow stripes along the ventrolateral margin of the forearm, tarsus and foot. The venter is creamy yellow to orange. This species is able to undergo metachrosis (color change), and the colors darken at night to a darker green and bluish purple. Metamorphs lack blue coloring and turn reddish brown at night and in preservative (Savage 2002).

Larvae are moderately sized and have a total length of 33 mm at stage 31. The eyes are dorsolateral and directed laterally and the nostrils are dorsolateral and directed anterolaterally. The tail is moderate, caudal fins are high and the tail tips are short. The oral disc is small and entire, with large, serrated beaks and 2/3 rows of denticles. The mouth is located anteroventrally and directed anteriorly. Papillae border the mouth in two rows and laterally scattered small papillae lie medially to the fringing row. The spiracle is ventral and sinistral to the midline (Duellman 2001).

Tadpoles have a heavily pigmented snout, top of head, and body, appearing grayish brown. The sides of the body are bluish gray, and the venter is light blue-gray with a silvery cast. The larval caudal musculature is a light gray brown. The caudal fins are clear with brown dashes on the proximal edges of the anterior half of the dorsal and ventral fins. During development, the pigmentation increases on the dorsal surface of the body and the caudal musculature, while the pigment in the caudal fins decreases. The iris is yellow (Duellman 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Costa Rica

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (49 records).

Agalychnis annae is found in northern and central Costa Rica in the humid premontane and lower montane areas on the slopes of the cordilleras. (Savage 2002). It occurs from low to moderate elevations, up to 1600 m (Duellman 2001).

Life History, Abundance, Activity, and Special Behaviors
This species is nocturnal and may be found in vacant lots and gardens in the metropolitan areas of the Meseta Central (Savage 2002).

The breeding season is during the rainy season from May to November. Calling males usually are found above ponds in hanging vegetation. Amplexus takes place 3 to 10 m above the ground. The female will carry the male, climbing down to a water source and then returning to vegetation to find a deposition surface for the eggs. Eggs are oviposited from 350 mm to 3 m above water (Duellman 2001) on leaves, branches or vines, contained within a clear jelly (Savage 2002). The eggs are pale green and are about 4 mm in diameter, including the envelope. Egg will become creamy tan with development. There are 47 to 162 eggs per clutch. Eggs hatch after about six days from oviposition. Tadpoles vigorously wriggle to free themselves from the egg capsule and will slide or drop, or be washed from vegetation into water. Laboratory raised tadpoles metamorphosed in 247 days, but development is probably more rapid under natural conditions (Duellman 2001).

Trends and Threats
Agalychnis annae is a declining species due to many factors, mainly chytridiomycosis. It has disappeared from many protected areas. This species is now found mainly in metropolitan San José near polluted streams, possibly because the chytrid fungus is more susceptible to pollution than A. annae. Predation on tadpoles from an introduced fish, Xiphophorus hellerii, also impacts this species. (IUCN 2006).

Megaselia scalaris fly larvae kill and feed on the healthy eggs of A. annae. Although this occurs infrequently overall, one population can be significantly diminished by M. scalaris predation. In August of 1980, M. scalaris larvae were found in 7 of 127 studied clutches in a private botanical garden near San Jose, Costa Rica. In a further experiment sparked by this study, .6-1.5 A. annae eggs per larva were destroyed by M. scalaris predation. There was also significantly reduced viability in M. scalaris-infested clutches of A. annae (28.3-57.2% hatching in the experimental group versus 98.3% hatching in the control group), possibly the result of fungal infestation, the secretion of digestive enzymes by M. scalaris larvae, or even the actions of other micro-organisms (Villa and Townsend 1983). Defenders of Wildlife and SSN have recently recommended that the United States advocate for inclusion of Agalychnis annae in Appendix II of CITES (Convention on International Trade in Endangered Species), which would recommend controls on commercial trade in this species. Agalychnis annae has been extirpated from much of its former habitat in Costa Rica.

All five Agalychnis species (A. annae, A. callidryas, A. moreletii, A. saltator, and A. spurrelli) have just received CITES protection, under Appendix II (as of March 21, 2010). Within the past decade the U.S. alone has imported 221,960 Agalychnis frogs, according to the Species Survival Network (SSN).

Relation to Humans
This species is found in the international pet trade (IUCN 2006), but detailed trade data are apparently unavailable, according to a recent commentary by the U. S. Department of Fish and Wildlife.

Possible reasons for amphibian decline

General habitat alteration and loss
Intensified agriculture or grazing
Predators (natural or introduced)
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments

A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).

References

Duellman, W. E. (2001). The Hylid Frogs of Middle America. Society for the Study of Amphibians and Reptiles, Ithaca, New York.

IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment: Agalychnis annae. www.globalamphibians.org. Accessed on 19 October 2007.

Savage, J. M. (2002). The Amphibians and Reptiles of Costa Rica:a herpetofauna between two continents, between two seas. University of Chicago Press, Chicago, Illinois, USA and London.

Villa, J. and D.S. Townsend (1983). ''Viable frog eggs eaten by phorid fly larvae.'' Journal of Herpetology, 17(3), 278-281.

Species Account Citation: AmphibiaWeb 2010 Agalychnis annae: Blue-sided Tree Frog <https://amphibiaweb.org/species/614> University of California, Berkeley, CA, USA. Accessed Dec 4, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 4 Dec 2024.

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