Pura Vida 5: Leaf-litter Amphibians

While walking through the forests of Costa Rica, an observant person can enjoy a wide variety of frog species inhabiting the forest floor. Many of these amphibians live low to or in the ground, among the leaves, preying upon a variety of food sources. Common prey items for smaller leaf-litter frogs are invertebrates, such as ants, beetles, or spiders. However, as you might predict, larger frogs eat larger prey items, such as other frogs, lizards, or even small mammals. Costa Rican frogs come in a variety of sizes. I measured young individuals of the genera Craugastor and Pristimantis as small as 6 mm in total length. Conversely, large toads, tree frogs, or Leptodactylus pentadactylus can easily reach the size of a human fist.

Chaunas (Bufo) marinus

Cane toads (Chaunas marinus) are commonly found hopping around man-made structures at night. Although an invasive exotic species in many other parts of the world, the Cane toad is native and incredibly common in Costa Rica.

Incilius melanochlorous

Incilius coccifer

Incilius valliceps?

Rhaebo haematiticus

A common denizen of the rainforest floor, Rhaebo haematiticus is cryptically-patterned. Some individuals can have pronounced "eye-spot" markings located toward the rear of their back.

Craugastor crassidigitus

Craugastor mimus

Craugastor bransfordii

This small litter frog is the most common amphibian found on the grounds of La Selva Biological Station. Although variable in color, it is often a mottled brown (as above) with tubercles marking the skin. It can usually be identified by its white throat, yellow stomach, and red groin. Unlike many other congeners, however, it lacks toe pads.

Craugastor megacephalus

I like to refer to this species as Craugastor largehead. Although it can be readily identified by its "large head", no other anuran species has a white spotted throat and stomach. This species was puzzling for me, however, as I only had success finding them on one trail.

Craugastor fitzingeri

C. fitzingeri is often found nocturnally perched on or near the forest floor during light rain.

Craugastor noblei. Quite uncommon, but they could be reliably turned up at my study site.

Craugastor talamancae. Like noblei, this uncommon species did inhabit my study site.

Diasporus diastema, the ubiquitous "tink" frog, known for the call it makes at night.

Pristimantis cerasinus can be identified by the dark red coloration on the back of its legs (not shown above). I had success finding this species perched on vegetation a few feet above the ground.

Pristimantis ridens is identified by tubercles above its eyes.

Gastrophryne pictiventris. I suspect this species is not commonly encountered due to its fossoriality. However, I did flip the one above under a palm leaf, and I found two moving out during a storm.

Oophaga pumilio. Incredibly common, incredibly beautiful. And for some silly reason, I never got a picture I'm pleased with. This species has some remarkable reproductive behavior. Unlike hylid species that lay eggs in or near large water sources, female O. pumilio lay fertilized eggs in moist leaf litter. Eventually, the males collect the hatching tadpoles on their back and carry them to bromeliads, where they are deposited. In these small "cups" of water, the tadpoles develop further, feeding on unfertilized eggs deposited by their mother.

Dendrobates auratus. Larger than O. pumilio (and more toxic?), these frogs are fun to photograph.

Phyllobates lugubris, the least commonly found but perhaps prettiest of La Selva's 3 dart frog species. This individual was scared out from underneath some leafy detritus.