Description The Dendrobates leucomelas snout-to-vent length ranges from 31 to 38 mm (Walls 1994). D. leucomelas is the largest species of its genus and females are usually bigger and thicker than males (Honolulu Zoo 2002). Adult frogs are black dorsally with three broad crossbands colored bright yellow, yellow-orange, or orange; black spots or blotches are often present in the crossbands as well as on the yellow or orange limbs. The belly is black and usually lacks color. All markings are variable, making each frog unique. Color pattern does not seem to be correlated with geography. D. leucomelas lacks an omosternum and the tarsal tubercle is absent or barely present (Walls 1994). Unique glandular adhesive pads are present on the toes and fingertips, helping D. leucomelas to climb and stay in stationary positions. D. leucomelas also lacks webbing on its feet. Although adult D. leucomelas have been illustrated extensively, no illustrations of this species' tadpoles exist (USGS 2002).
Dendrobates leucomelas is found in the Guianan Orinoco drainage of Venezuela north to the Río Orinoco, east into Guyana to the Essequibo River, south into extreme northern Brazil, and west into eastern Amazonian Colombia (Amphibian Species of the World AMNH website). They are native to South America but in 1994 one specimen was collected on Honolulu, Oahu, Hawaii, possibly due to a pet release (USGS 2002). D. leucomelas prefers moist or wet, forested, lowland regions and temperatures often reaching 30° C or warmer (Silverstone 1975; Honolulu Zoo 2002). They are usually found between 50 and 800 meters above sea level in leaf litter, fallen trees, forest floors, stones and occasionally trees (Honolulu Zoo 2002; Walls 1994).
Life History, Abundance, Activity, and Special Behaviors Dendrobates leucomelas is an insectivore (mostly ants) and is diurnal (USGS 2002; Caldwell 1996; Silverstone 1975). D. leucomelas is toxic in its natural environment and derives its skin toxins from the ants in its diet (Caldwell 1996). It is the only poison frog known to estivate during the dry season (Walls 1994). Males will chirp, buzz, trill, and hum to get females attention while also showing off their brightly colored bodies for an hour or two after sunrise and before sunset (Honolulu Zoo 2002; Walls 1994). Once a female chooses a male she will follow him to his area and stroke his back and snout. Sometimes both the male and female will slowly circle one another and stamp their feet (Walls 1994). The D. leucomelas females compete for males, and the terrestrial eggs are guarded by the male parent in a moist, sheltered area (USGS 2002).
Females lay 100 to 1000 eggs per year and produce 2 to 12 eggs per clutch (Honolulu Zoo 2002). The male rotates the eggs every so often so that they receive enough oxygen. Unlike most historionicus-group dendrobatids, the D. leucomelas tadpoles do not rely on eggs for nutrition; but they will accept almost anything for food (Walls 1994). Once they hatch, the tadpoles are carried on the father's back to small pools of water where they continue to develop (USGS 2002; Richard Stockton College 2002). Metamorphosis takes 70 to 90 days; froglets resemble miniature adults but have duller colored bands. In captivity the froglets must eat regularly (fruit flies, pinhead crickets, and other small insects); going without food for 48 hours can lead to death. Some people have observed that they have a "sweet tooth" for small caterpillars (Walls 1994).
Trends and Threats Since D. leucomelas is easily bred in captivity, the selling price on the international market has decreased (Barrio & Fuentes 1999). D. leucomelas is abundant in all places sampled by Barrio and Fuentes in the late 1990's. However, there has not been thorough monitoring to determine the current status of these frogs (Barrio & Fuentes 1998). Dendrobatids are exploited for the pet trade and it is believed that they are overharvested in some areas. They could face declines unless strict trade regulations are set. (CITES 2002). Their habitat is also being destroyed by timber industries and agriculture.
Relation to Humans Humans keep D. leucomelas for pets and are popular species in the pet trade (USGS 2002). Some compounds of their skin have pharmacological properties, and have proved to be valuable in biomedical research (Honolulu Zoo 2002).
Possible reasons for amphibian decline
General habitat alteration and loss Habitat modification from deforestation, or logging related activities Intensified agriculture or grazing Habitat fragmentation Intentional mortality (over-harvesting, pet trade or collecting)
Comments Similar Species: Dendrobates auratus is an established exotic dendrobatid in Hawaii and most closely resembles D. leucomelas (USGS 2002). However, D. auratus does not have three distinct crossbands (McKeown 1996). Due to the absence of the omosternum, D. leucomelas is considered a close relative to D. historionicus (also lacking the omosternum). But Myers and colleagues have removed D. leucomelas from the historionicus-group due to its differences in call (Walls 1994). It has also been placed in the tinctorius-group because of its similarities to others in that group with tadpole behavior, aspects of color pattern, and its resemblance to D. auratus and D. tinctorius. It has also been successfully bred with D. tinctorius and D. truncates (Walls 1994).