Microhyla heymonsi

Darkside Narrowmouth Frog Microhyla heymonsi
Darkside Narrowmouth Frog at night near pond in Bang Kapi

Dark-sided Chorus Frog Microhyla heymonsi
Dorsal view of same frog

Darkside Narrowmouth Frog Microhyla heymonsi
View of same frog from front

Dark-sided Chorus Frog Microhyla heymonsi
Darkside Narrowmouth Frog in forest in Khao Yai

Dark-sided Narrowmouth Frog Microhyla heymonsi
Darkside Narrowmouth Frog near canal in Cambodia

Dark-sided Chorus Frog Microhyla heymonsi
Darkside Narrowmouth Frog on plant in Bang Kapi

Darkside Narrowmouth Frog Microhyla heymonsi
Darkside Narrowmouth Frog in empty lot in Bang Kapi

Microhyla heymonsi mating Eduard Galoyan
Darkside Narrowmouth Frogs mating in Vietnam (photo by Eduard Galoyan)

Microhyla heymonsi mating Eduard Galoyan
Darkside Narrowmouth Frogs mating in Vietnam, with eggs (photo by Eduard Galoyan)

Darkside Narrowmouth Frog Microhyla heymonsi Eduard Galoyan tadpole
Tadpole of Darkside Narrowmouth Frog in Vietnam (photo by Eduard Galoyan)

English name: Darkside Narrowmouth Frog (aka “Dark-sided Chorus Frog”)
Scientific name: Microhyla heymonsi
Thai name: Ung khang da

Description: Up to 2.5cm long. A tiny squat frog with a pointed nose that gives the entire body a triangular shape. Light brown on top, sometimes with a thin light line going down the back. May have other faint markings on the body and legs. Sides are characteristically dark, though sometimes the dark coloration only appears on the very top of the sides. Underside is creamy white.

Tadpoles are approximately 1.5cm long, with a “guitar” shape and a protruding mouth. They are dark in the middle and transparent elsewhere.

Call: A series of clicking runs, similar to the Mukhlesur’s Narrowmouth Frog.

Similar Species: Inornate Froglet is flatter, has distinct black markings, and will hop around like a flea when exposed.
Mukhlesur’s Narrowmouth Frog has a dark marking on the back and lighter sides.
Asian Painted Frog is larger and heavier with a broader snout and cream-colored band on the side.

Habitat: Found in forest, agricultural areas, and empty lots. Hides under cover during the day, coming out at night or during rain. Breeds in rain puddles, ponds, marshes, and other shallow bodies of still water.

Place in the ecosystem: Eats ants and other small insects. Eaten by birds, snakes, lizards, larger frogs, and even large insects and arachnids.

Danger to humans: No danger to humans.

Conservation status and threats: Because of its large populations and ability to utilize a range of habitats (including those affected by humans), it has no conservation threats at this time.

Interesting facts: Though the Darkside Narrowmouth Frog and Mukhlesur’s Narrowmouth Frog have a similar size and diet, I have almost never found them in the same exact spot. All species have an ecological “niche” that they prefer – and if their “niches” were the same, then these two otherwise similar species would compete with each other and one would eventually outcompete and eliminate the other. In my experience the Darkside Narrowmouth Frog is often found in areas with permanent water sources, while Mukhlesur’s Narrowmouth Frog is more often found in areas with temporary water sources. This may or may not be the ecological difference that keeps them from competing directly, but it would take more extensive research to verify these anecdotal observations.

References:
Ecology Asia: Dark-sided Chorus Frog
The IUCN Red List: Microhyla heymonsi
Amphibians of the World: Microhyla heymonsi