AnimaliaHighest rank in taxonomy. Groups all life into domains: Animalia, Plantae, Fungi, etc.IUCN CRInternational Union for Conservation of Nature — the world authority on species extinction risk, using standardized criteria. — Critically Endangered — faces an extremely high risk of extinction in the near future.In ProgressCurrent stage of this record in the editorial review workflow. Recent Sighting
Hyloscirtus colymba
Stream Gliding Treefrog
(Gaige, 1922)
Detailed Texts Multi-lang
A medium-sized, slender tree frog beautifully adapted to riparian mountain environments. The dorsal coloration is typically a soft pale green, yellowish-green, or brownish-green, heavily punctuated by fine dark brown dots or scattered light spots. Its skin is smooth on the back but granular on the belly. The eyes are large and prominent with a grayish-bronze to silver iris and a horizontal pupil. The limbs are long and thin; fingers and toes feature extensively developed webbing and large, rounded adhesive digital discs. A distinctive anatomical trait is the presence of a mental gland on the chin of adult males, used during chemical communication in courtships.
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Anonymous Curator
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Last modified by
Julia Trouin
TaxonomyBiological classification ranks placing this species within the tree of life, from Kingdom down to Genus.
PhylumRank below Kingdom. Groups organisms sharing a fundamental body plan (e.g., Chordata = vertebrates and some invertebrates).Chordata
ClassRank below Phylum. Subdivides by structural traits (e.g., Mammalia, Aves, Reptilia, Insecta).Amphibia
OrderRank below Class. Groups related families sharing common ancestry (e.g., Carnivora, Primates).Anura
FamilyRank below Order. Groups closely related genera (e.g., Felidae = cats, Canidae = dogs).Hylidae
GenusRank just above Species. The first word in the two-part binomial scientific name.Hyloscirtus
Taxonomic AuthorityThe scientist who first formally described and published this species, followed by the year of publication.(Gaige, 1922)
Record Completeness
96%Coming soon
Ecology & StatusHow this species lives: habitat preferences, diet, behavior, population status, and role in its ecosystem.
OriginWhether the species is native (evolved here), endemic (found only here), or introduced by human activity.
Native
Population TrendDirection of change in population size over time: increasing, stable, decreasing, or unknown.
Unknown
Breeding SeasonTime of year when this species typically reproduces or flowers.
Wet Season
Trophic RolePosition in the food chain: producer, herbivore, carnivore, omnivore, decomposer, or parasite.
Carnivore
Recent SightingsWhether this species has been observed in the wild in Costa Rica within recent years.
Yes
Habitat SummaryOverview of the specific ecosystems and environments where this species is found in Costa Rica. Multi-lang
Strictly associated with pristine, fast-flowing rocky mountain streams and torrents within humid premontane and lower montane rainforests. It spans elevations from 560 up to 1,400 meters above sea level along both the Atlantic and Pacific slopes of Costa Rica and western to central Panama, requiring clean undisturbed water and abundant overhanging riparian vegetation.BehaviourDaily activity patterns, movement, territory use, foraging style, and seasonal behavioral changes. Multi-lang
Exclusively nocturnal and highly torrent-adapted. During the day, adult frogs sleep well-camouflaged on the undersides of leaves overhanging active streams. At night, they emerge to forage. Adult males establish calling sites on low ferns, shrubs, or mossy rocks right next to the splashing water, emitting low, periodic, click-like vocalizations designed to cut through the heavy white noise of rushing rapids.Social ActivitySocial structure: whether the species is solitary, paired, or colonial; hierarchy and communication. Multi-lang
Displays structured spatial organization during breeding seasons. Adult males defend calling territories on plants directly facing fast-water sections. Courtship is intricate, requiring close-range alignment facilitated by chemical signals from the male mental gland to complement the sound communication in high-noise environments.Feeding GuildWhat the species eats, how it forages or hunts, and its role as a consumer in the food web. Multi-lang
Riparian nocturnal invertivore and specialized stream-border insectivore.Trophic Chain DetailsSpecific interactions in local food webs: prey species, predators, competitors, and scavengers. Multi-lang
Functions as a specialized riparian carnivore preying on stream-side insects, small moths, flies, and aquatic macroinvertebrate adults emerging from the water. Adults are targeted by nocturnal stream-dwelling snakes, large spiders, and predatory birds. The scraping tadpoles function as primary consumers, feeding on benthic diatoms and biofilm coating torrent rocks.Reproductive BehaviourMating strategies, courtship displays, nesting or spawning behavior, and parental care. Multi-lang
Reproduction occurs within the river system. Amplexus takes place on vegetation hanging directly over fast currents. Females deposit egg masses in compact gelatinous clusters attached to the undersides of leaves or mossy rocks right above the splash zone. Upon hatching, the larvae slide down directly into the highly oxygenated torrents, instantly utilizing their adaptive ventral suction discs to secure themselves to underlying gravel and rocks.Physical Measures
Length (cm)
3.6 - 5.1 cm
Weight (Grams)
3.5 g - 9 g
Offspring per cycleTypical number of young (live births, eggs, or seeds) produced by one adult in a single reproductive event or breeding season.40 - 120
Sexual DimorphismObservable physical differences between males and females of the same species (e.g., size, coloration, features).Yes
Lifespan
Sexual MaturityAge at which the individual becomes capable of reproducing for the first time.
12 - 18 Months
Gestation / IncubationDuration from fertilization to birth (mammals) or to hatching (egg-laying species).
14 - 20
Lifespan EstimatedExpected duration of life from birth to natural death under wild conditions.
Males3 - 6 Years
Females3 - 7 Years
Sexual DimorphismPhysical differences in size, coloration, or morphology between males and females of this species.
Males Multi-lang
Adult males are slightly smaller, measuring between 3.6 and 4.2 cm snout-vent length. They are uniquely diagnosed by the presence of a distinct circular mental gland on the apex of the chin, which secretes socio-sexual courtship pheromones, and they possess internal vocal structures.
Females Multi-lang
Adult females are robust and larger, ranging from 4.4 to 5.1 cm snout-vent length. They completely lack any visible mental gland modifications or internal vocal structures, presenting a clean uniform throat profile and showing a broader, wider pelvic cavity.
Evolutionary AdaptationsInherited traits and behaviors that improve the species' survival and reproduction in its specific environment. Multi-lang
Extensive, full interdigital webbing coupled with large adhesive digital pads that allow stable movement on slick, spray-splashed rocks and vertical stream-side surfaces.
Specialized rheophilic tadpoles equipped with an enlarged, belly-like suctioning oral disc that acts as an anchor to cling onto submerged river rocks within crushing water currents.
Main ThreatsDocumented pressures reducing the population: habitat loss, hunting, disease, climate change, and invasive species. Multi-lang
Devastating population crashes driven by chytridiomycosis (Batrachochytrium dendrobatidis), an infectious fungal disease that has wiped out high-altitude stream amphibian communities across Mesoamerica.
Habitat loss resulting from stream siltation, water pollution from agricultural runoff, and the removal of pristine gallery forests along mountain banks.
Interesting FactsSurprising or notable facts that highlight what makes this species unique or ecologically important. Multi-lang
The specific epithet 'colymba' comes from the Greek word for 'diver' or 'swimmer', given in honor of the unique evolutionary engineering of its tadpoles, which spend months feeding inside intense, highly oxygenated rapids.