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Amolops formosus

Amolops formosus, also known as the Assam sucker frog, is a species of frog found in the high-gradient streams of northern India, northern Bangladesh, and Nepal. It is characterized by its green dorsum with chocolate-colored blotches and yellow dots, and fully webbed toes with discs, distinguishing it as a specialized inhabitant of fast-flowing water environments.

Key Facts

  • Found in high gradient streams of northern India, Bangladesh, and Nepal.
  • Adult males measure around 64 MM snout-to-vent length, while females range from 63–73 MM.
  • Possesses fully webbed toes with discs and smooth skin, adapted for aquatic life.
  • Dorsum is green with irregular chocolate-colored blotches and yellow dots.
  • Threatened by habitat loss due to deforestation and dam construction.
  • Inhabits tropical evergreen forests at elevations between 1,000–2,508 meters.
Amolops formosus
Scientific Name
Amolops formosus
Family
Ranidae
Common Names

Assam Sucker Frog, Beautiful Stream Frog, Assam Cascade Frog, Hill Stream Frog

Description
Amolops formosus is distinguished by its striking coloration and adaptations for a fast-flowing water environment. Adult males reach approximately 64 mm in snout-to-vent length, while females are slightly larger, measuring between 63–73 mm. The head is notably wide, and the tympanum, though small, is clearly visible. Its fingers lack webbing, but the toes are fully webbed, and both digits possess adhesive discs. The skin is smooth. The dorsal surface is a vibrant green, adorned with irregular, dark chocolate-colored blotches speckled with yellow dots. The ventral side is pale, with the abdomen exhibiting a greenish hue.
Habitat Description
This species is closely associated with high-gradient streams and the riparian vegetation found within tropical evergreen forests. It typically inhabits these environments at elevations ranging from 1,000 to 2,508 meters above sea level. Its presence is linked to the unique conditions of these fast-flowing water systems.
Size Range Mm
63–73 mm
Habitat Type

Tropical Evergreen Forest, Streams, Riparian Zones

Distribution States

Arunachal Pradesh, Northern India, Northern Bangladesh, Nepal

Distinguishing Features
  • Fully Webbed Toes With Discs
  • Green Dorsum With Irregular Chocolate-Colored Blotches and Yellow Dots
  • Smooth Skin
  • Wide Head
  • Adaptations For High-Gradient Streams

About Amolops formosus

Amolops formosus, commonly known as the Assam sucker frog, is a rare amphibian species inhabiting the fast-flowing streams of northern India, northern Bangladesh, and Nepal. Its scientific classification places it within the genus Amolops of the Ranidae family. This frog is specifically adapted to life in high-gradient streams, a niche that has led to its unique physical characteristics and restricted distribution.

Description and Adaptations

Adult specimens of Amolops formosus exhibit distinct sexual dimorphism in size, with males measuring around 64 mm (2.5 in) and females ranging from 63–73 mm (2.5–2.9 in) in snout-to-vent length. A key feature is its fully webbed toes, equipped with adhesive discs, which are crucial for maintaining grip in turbulent waters. The fingers, conversely, are not webbed. The frog's skin is smooth, and its head is relatively wide. The dorsal coloration is a vibrant green, marked by irregular, chocolate-colored blotches interspersed with yellow dots, providing camouflage against the stream bed and vegetation. The ventral side is pale, with a greenish abdomen.

Habitat and Distribution

Amolops formosus is intrinsically linked to streams and the surrounding riparian vegetation, typically found within tropical evergreen forests. It prefers higher elevations, with documented occurrences ranging from 1,000 to 2,508 meters (3,281–8,228 ft) above sea level. Its distribution is primarily concentrated in the northern regions of India, Bangladesh, and Nepal. While records suggest a possible presence in Bhutan, these may be confused with closely related species, such as Amolops himalayanus, which has been treated as a synonym of A. formosus in some assessments.

Conservation Concerns

This species is considered rare and faces significant threats to its survival. Habitat loss, driven by deforestation and the construction of dams, poses the most substantial risk. These human activities directly degrade and fragment the stream environments essential for the frog's life cycle, making conservation efforts focused on habitat preservation critical for its continued existence.

Source: Wikipedia ↗

Frequently Asked Questions

What are the common names for Amolops formosus?

Amolops formosus is also known by several common names, including the Assam sucker frog, beautiful stream frog, Assam cascade frog, and hill stream frog.

Where is Amolops formosus found?

This species is found in the high gradient streams of northern India, northern Bangladesh, and Nepal. It may also be present in Bhutan, though this is uncertain.

What does Amolops formosus look like?

Amolops formosus has a green back with distinct chocolate-colored patches marked by yellow dots. Its underside is light-colored, with a greenish abdomen. Both its fingers and toes have discs, and its toes are fully webbed.

What is the habitat of the Assam sucker frog?

The Assam sucker frog lives in streams and along the vegetation bordering them, primarily within tropical evergreen forests. It prefers elevations ranging from 1,000 to 2,508 meters above sea level.

What are the threats to Amolops formosus?

The primary threats to Amolops formosus are habitat loss caused by deforestation and the construction of dams. These factors reduce the availability and quality of its essential stream habitats.