© 2010 Division of Herpetology, University of Kansas (1 of 1)
Diagnosis: Isthmohyla calypsa can be distinguished from all other congeners by the following character combination: highly tuberculate and spiny dorsal surfaces of head, body and limbs; coloration in life bright metallic green with brown blotches; dorsal thigh surfaces free of transverse bars; lack of conspicuous markings on anterior and posterior thighs; lack of tarsal fold; chin and throat bright white with a few dark brown spots near the margins; short, truncated snout; male prepollex with numerous small black spines; paired vocal slits in males; call usually a single ascending note (sometimes two notes) (Lips 1996); male size 26-36 mm SVL and female size 31-41 mm SVL (Savage 2002).
Description: Isthmohyla calypsa is a moderately small, bright, metallic green treefrog with dark, olive green to brown blotches as markings. Adult male SVL is 26 to 36 mm while adult female SVL is 31 to 41 mm. Conspicuous tubercular spines cover the upper surfaces, and females are much spinier than the males. The venter is strongly granular. The head is wider than long, with a short, truncated snout. Eyes are large. The tympanum is distinct and has a diameter about 4/5 the diameter of the eye. Vomerine teeth are present in a transverse series, with the anteriormost located between the subcircular, widely spaced choanae. Vocal slits are paired, small, and round, and adult males have fully distensible single external subgular vocal sacs. Fingers are short and thick, with medium-sized finger discs; the width of the disc on Finger III is slightly smaller than the diameter of the tympanum. Under Finger IV, the distal subarticular tubercle is usually bifid. No palmar tubercle is present. Fingers are weakly webbed, with vestigial webbing between Fingers I and II. The prepollical pad is somewhat enlarged. Male nuptial pad at base of thumb has numerous black spines. A series of warts extends along the outer margin of the forearm, and there is a series of spines along the outer margin of both the tarsus and the foot. Toes are strongly webbed. The inner metatarsal tubercle is low, flat, and shaped like an ellipse, while the outer metatarsal tubercle is small and subconical. An inner tarsal fold is present (Lips 1996; Savage 2002).
In life, the upper surfaces of Isthmohyla calypsa are shining metallic green with a few large dark olive green to brown blotches in males. Dark mottling is present in females. Lips are striped with green and dark brown bars. Groin is bright white with some black spots. Irregular transverse dark bars are present on dorsal surfaces of limbs. Anterior and posterior surfaces of the thigh are gray to white, with tiny black spots. The venter is dirty white with numerous black flecks and some large black blotches. Iris is cream-colored with irregular brown line around the margin. Palms and soles vary from gray-white to pale lemon yellow; in some individuals, numerous black dots are present on the palms. No other Costa Rican frog is covered by spines on the upper surfaces of head, body, and limbs (Lips 1996; Savage 2002).
Larvae are large, measuring 54 mm in total length at stage 37. Larval body is depressed. Mouth ventral, nostrils dorsal, eyes dorsolateral. Spiracle lateral and sinistral; vent tube is dextral. Tail is long, with low fins. Tail tip is rounded. Oral disc is small with tiny beaks and 2/3 rows of denticles; A2 with narrow gap above mouth. Beaks have medium-sized serrations. Two or three rows of small papillae border the mouth, and many additional papillae are present in ventrolateral folds. Series of large submarginal papillae present. Larval body is olive brown suffused with orange. Tail musculature is the same color as body, but with darker gray splotches at the midline and on anterior half of tail. Posterior portion of tail has large black spots, especially in larger tadpoles. Tail fin is translucent (Lips 1996; Savage 2002; Lips and Savage 1996).
Similar species: I. calypsa can be distinguished from I. lancasteri by skin texture (spiny in I. calypsa vs. smooth to bumpy in I. lancasteri), nuptial excrescences (black in I. calypsa vs. brown flattened pad in I. lancasteri), smaller average mass (1.8 g in I. calypsa vs. 2.2 g in I. lancasteri), and lack of transverse barring on dorsal and posterior thigh surfaces (vs. dorsal and posterior thigh surfaces with transverse bars in I. lancasteri). I. calypsa tadpoles can also be distinguished in appearance (more streamlined: relatively longer tail, smaller fins, relatively short, flattened, and thinner body; eyes are larger and more anterior and the snout is truncate) from those of I. lancasteri (more robust, rounded tadpole body; rounded snout; shorter tail). The call of H. calypsa lacks harmonics and males rarely overlap notes; in contrast, the call of H. lancasteri always has one and sometimes two harmonics, and males frequently overlap calls with neighbors (Lips 1996).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Costa Rica, Panama
Life History, Abundance, Activity, and Special Behaviors
Most females return to the same general area to breed each year. Like the males, females also show considerable site fidelity. Females, juveniles, and many males all arrive at the breeding stream two weeks before the beginning of the rainy season. Juveniles disappear after two days, and females mate only after the first rains. Amplexus and oviposition take place near the male's calling sites but usually on lower vegetation; females leave the area after oviposition (Lips 1998; Lips 2001).
Females lay only one clutch per visit and up to three clutches during breeding season. Earlier clutches have more eggs than clutches laid later in the season. Clutches consist of 10 to 36 creamy yellow colored eggs. Generally eggs are oviposited on the underside of leaf surfaces 130-170 cm above the water surface, with only a small percentage of clutches (6% of clutches observed by Lips 2001) deposited on the upper surfaces of leaves. Lips (2001) also reported that about 22% of clutches were deposited on vegetation over land rather than directly over water; however, if the stream had flooded, most of these would have been over water. Eggs are large, around 3.6 mm in diameter (range 2.8-4.4 mm) and are enclosed in jelly capsules of about 5.3 mm in diameter. Early embryos are chocolate-gray in color and hatch 23 to 56 days after oviposition (Lips 1998; Lips 2001).
After hatching, tadpoles fall or are washed by rain into the stream below. Tadpoles are classified as mountain brook ecomorphs; they lack a specialized oral disc, and inhabit slow-moving portions of the stream and pools along the stream. Tadpoles often hide among the rocks and leaves at the bottom of the stream. In the laboratory, tadpoles metamorphosed in around 270 days after oviposition. Metamorphs are around 15 mm in standard length. Based on recapture data, adults live at least four years; sexual maturity is reached during the first year of life (Lips 1996; Lips 1998; Lips 2001).
Eggs suffer significant parasitism from drosophiliid flies (Hirtodrosophila batracida), which lay eggs on new frog clutches; the maggots generally consume the entire parasitized clutch. Crickets or other orthopterans also prey on the eggs. Of 618 clutches studied between 1991 and 1996, 65% did not hatch any tadpoles; 35% of those mortalities were due to fly parasitism. Clutches laid later in the season suffered significantly higher mortality from fly parasitism (9.5% for the earliest clutches, vs. 48.5% for clutches laid in the middle of the season, and 52.25% for those laid at the end of the season). Desiccation was the most significant cause of mortality for earlier clutches (Lips 2001).
Trends and Threats
Increased livestock farming may also present a threat to this species (Stuart et al. 2008).
Isthmohyla calypsa has been recorded from at least one protected area, Parque Internacional La Amistad in Costa Rica, and it may also occur in Parque Nacional Volcán Barú, in Panama (Stuart et al. 2008).
Possible reasons for amphibian decline
General habitat alteration and loss
Isthmohyla calypsa was previously included in Isthmohyla lancasteri, but it has been distinguished from that species based on adult and larval morphology, oviposition site (leaves for I. calypsa vs. attached to submerged vegetation and debris in small pools of slow-flowing streams for I. lancasteri), egg and clutch characteristics (10-36 yellow eggs per clutch for I. calypsa, vs. 70-80 chocolate-brown eggs for I. lancasteri) and vocalizations (Lips 1996).
The specific epithet calypsa derives from the Greek nymph Calypso, who hid the hero Ulysses. It refers both to the frog's camouflage and to the species having been hidden within H. lancasteri (Lips 1996).
Lips, K. L., and Savage, J. M. (1996). ''Key to the known tadpoles (Amphibia: Anura) of Costa Rica.'' Studies on Neotropical Fauna and Environment, 31, 17-26.
Lips, K. R. (1995). ''The population biology of Hyla calypsa, a stream-breeding treefrog from Lower Central America.'' Ph. D. dissertation, University of Miami, Coral Gables.
Lips, K. R. (1995). The population biology of Hyla calypsa:--a stream-breeding treefrog from lower Central America. Ph. D. dissertation. University of Miami, Coral Gables, FLA.
Lips, K. R. (1996). ''New treefrog from the Cordillera de Talamanca of Central America with a discussion of systematic relationships in the Hyla lancasteri group.'' Copeia, 1996(3), 615-626.
Lips, K. R. (1998). ''Decline of a tropical montane amphibian fauna.'' Conservation Biology, 12(1), 106-117.
Lips, K. R. (2001). ''Reproductive trade-offs and bet-hedging in Hyla calypsa, a Neotropical treefrog.'' Oecologia, 128(4), 509.
Lips, K. R. (2005). ''Quantification of selection and male reproductive success in Hyla calypsa, a Neotropical treefrog.'' Ecology and Evolution in the Tropics: A Herpetological Perspective. M. A. Donnelly, B. I. Crother, C. Guyer, M. H. Wake, and M. E. White, eds., .
Lips, K. R., Green, D. E., and Papendick, R. (2003). ''Chytridiomycosis in wild frogs from southern Costa Rica.'' Journal of Herpetology, 37, 215-218.
Lips, K.R., Reeve, J.D., and Witters, L.R. (2003). ''Ecological traits predicting amphibian population declines in Central America.'' Conservation Biology, 17(4), 1078-1088.
Lötters, S., Kielgast, J., Bielby, J., Schmidtlein, S., Bosch, J., Veith, M., Walker, S. F., Fisher, M. C., and Rödder, D. (2010). ''The link between rapid enigmatic amphibian decline and the globally emerging chytrid fungus.'' Ecohealth, doi: 10.1007/s10393-010-0281-6.
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.
Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
Written by David Chen (davidchen AT berkeley.edu), UC Berkeley
First submitted 2008-04-25
Edited by Kellie Whittaker, Michelle Koo (2019-07-16)
Species Account Citation: AmphibiaWeb 2019 Isthmohyla calypsa <http://amphibiaweb.org/species/753> University of California, Berkeley, CA, USA. Accessed Oct 21, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Oct 2020.
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