Common Amphibians of Assam - I

Contribution and Photo Credits by

Dr Saibal Sengupta

Assam Don Bosco University, Tapesia Gardens, Kamarkuchi, Sonapur, Tepesia, Assam 782402

&

Dr Abhijit Das

WiIldlife Institute of India, Chandrabani, Dehradun, Uttarakhand

The name amphibian is derived from Greek amphibios meaning "a double life". This is because in general amphibians need both water and land to complete their life cycle, the tadpole are aquatic and the adults are terrestrial.

The Assamese name Bhekuli probably derived from the Sanskrit legend Bheki, the name given to a frog that symbolizes the sun on the horizon.

Amphibia originated in the early Devonian period (370 mya), flourished in late Devonian and Carboniferous and since then represents a highly diversified group (8156 sps; Frost, 2020) of vertebrate even in the era of mammals (6495 sps; Burgin, et al. 2018). There are three lineages of modern amphibian, Viz. Anura (toads & frogs), Caudata  (Salamanders & Newts) and Gymnophiona (limbless amphibians, caecilians).

Assam is an antique treasure of the country and known worldwide for rich biodiversity including cultural diversity. Highly diversified landscapes with numerous specific ecosystems operating within each of them makes the region paradise of life and also justifies its unique position, being the part of two biodiversity hot spots namely, Himalaya and Indo Burma, among 36 hotspots of the world.

The amphibian fauna of the state of Assam is yet to be explored totally. Despite lack of information, Assam supports a species-rich amphibian fauna. So far 61 species of Anura (seven families and 31 genera) and four species of Gymnophiona (two families and two genera) have been recorded. Here some common amphibian of Assam is described.

Family: Bufonidae

1.  Duttaphrynus melanostictus 

   Asian Common Toad (Ass: Chuk bhekuli) 

    

   A sturdy toad (SVL = 76.00mm) with variable colour from yellowish-brown to dark brown. Head with black bony ridges. Parotid glands large, elliptical and kidney-shaped. The skin of the dorsal surface rough and bears prominent dark-tipped warts of various shapes and sizes.

It is abundantly found in damp places very common in and around human habitation. The toad has two breeding seasons: pre-monsoon and post-monsoon. Females laid eggs in static and slow-flowing water in the forms of “string”, entangled in the aquatic vegetation.

This is a very common species which is distributed throughout Assam.

Family: Microhylidae

    2.  Microhyla mymensinghensis  

  Mymensingh Narrow Mouthed Frog (Ass: Paruwa Beng)

    

    Small frog (SVL 16.5 mm) with hidden tympanum. Dorsal colour varying from dark brownish to greyish. Dark marking extends from between the eyes widening to the posterior back. A dark X shaped marking on the dorsum and a crescent-shaped black marking on the anus are present.

 

Sub-fossorial in habit, inhabits different habitat types like lowland scrub forest, grassland, agricultural land, pastureland and urban areas. Very commonly found in leaf litter and amongst moist herbaceous vegetation. The frog is active only during monsoon and it breeds in ephemeral water bodies. This is a widely distributed common frog of the state.

    3.  Uperodon globulosus 

      Indian Balloon Frog 

    

    Globular shaped frog (SVL 57.00 MM) with a small broad head. Snout short and blunt. Nostril and eye are very small. The tympanum is absent. Skin is almost smooth on the dorsal side of the body. Dorsal colour is uniform brown with yellow or white spots.

This is an excellent burrower and its powerful metatarsal tubercles help it to burrow quickly and disappear. It comes out after heavy shower for breeding and has a duck-like strong mating call. Generally, this frog is found in the months of June, July and August and it lays eggs on temporary water pool. This is species more commonly found in the north and west Assam.

4. Kaloula pulchra 

Painted ballon frog

This is a large sized frog with (75.00 mm), subtriangular shaped body. The limbs are involved in body skin. The tympanum is hidden. Dorsally the frog is dark brown with two dorso-lateral elongated broad yellow patches run from between the eyes. It inhabits tropical forest and also riparian vegetation near human habitation. A fossorial species could be seen only during the breeding period in early monsoon.

This frog is very common around ponds and pools in southern Assam (Barak valley and parts of N.C. hills).

Family: Rhacophoridae

                                   5. Polypedates teraiensis 

                                 Terai Tree Frog (As; Pat beng)
 

It is an arboreal frog with medium body size (SVL 75.00 mm). Head is slightly long with the pointed snout;. Rough cephalic skin is co-ossified with the skull bone, especially in the inter-orbital region. Finger and toe tips are dilated into adhesive discs. Dorsally the species is yellowish-brown, can change to dark brown or conversely to light grey. There are three to four longitudinal streaks extending from the snout to vent which may often be faintly visible. Limbs are with dark cross bands. The ventral surface is almost white.

This arboreal species is a very common species around the human habitat as well as in the deep woods. Males call from overhanging vegetation or sitting on the bank of water bodies like rain pools, ditches or ponds, slow-flowing water channels. The call appears to be loud, high pitched “trrrruk”. Breeding occurs from April to August. Eggs are laid in a foam nest on over-hanging vegetation, rocks, walls or slope of banks of water bodies.

This species is very common in human habitation and is distributed throughout Assam.

6.Rhacophorus bipunctatus

Twin- Spotted Tree Frog (As: di futuki pat beng)

Rhacophorus bipunctatus is a medium size frog (SVL 45.00 mm). Dorsal colour is slate green and ventrum is bright yellow.  Prominent purple black spots are present on flanks.  Tips of fingers and toes dilated into discs. Fingers are two-third webbed while the toes are fully webbed. Webs are orange or red coloured. 

It inhabits closed-canopy evergreen forest, forest edge, and bamboo thickets; breeds during April to June by constructing foam nests on tree branches and lianas overhanging water bodies. A widely distributed species specifically common in areas near the forest.

Family: Ranidae

7. Amolops assamensis

Assamese Cascade Frog (As:  Nijora beng)

This is a large stream frog (SVL 94.00 mm), with elongated head and obtusely pointed snout.  A distinct pineal body is present. Fingers and toes at tips bear large discs. Toes fully webbed. Dorsal ground colour olive green with rounded or irregular brown patches. The lateral part of the head olive green. The tympanum is reddish-brown. The limbs are dull yellow and barred with reddish-brown.

Tadpoles are with an abdominal sucker, and postorbital and ventral glands. This species is found round the year in fast-flowing streams and waterfalls with rocky base. This hides in the crevices of the rocks of the streams and is kept wet by sprinkling water of the stream. The frog can stick vertically on a rock. The tadpoles are also found clinging on rocks of the stream can move vertically or horizontally on wet rocks with the help of adhesive sucker. This is common species of the streams of Brahmaputra valley.

8. Clinotarsus alticola

Assam Hill Frog (As: Nak jonga beng)

This is a medium built frog (SVL 70 mm), with a slender body, elongated head and acutely pointed snout. The tympanum is distinct and transparent. Fingers and toes are with pear-shaped disc at the tip. Dorsally light brown to dark brown. Two narrow light – edged with darker on outer side dorso-lateral folds run-up to the groin. During the breeding season, the male becomes bright yellowish-orange.

The species is encountered near a stream in hilly terrain and in associated riparian vegetation. Whistling males can be found during monsoon. Tadpoles are seen year-round in a slow-flowing stream. The tadpoles have a distinct eye mark on the tail. The species is quite common in Assam except in east (Upper) Assam.

9. Humerana humeralis

Bhamo Frog (As: daloni beng)

This is a medium-size ranid frog (SVL 70.00 mm), with an elongated head and pointed snout. Fingers and toes are with pear-shaped discs. Dorsally green to olive-brown with some dark spots. Ventrally, throat, chest, belly and forelimbs are white. A white line on flank extends to the upper jaw. The dorsolateral fold is bright yellowish silvery colour, extends from behind the eye to groin. Male possesses humeral gland at the base of the forelimb.
It utilizes various habitats like waterlogged area, wet grassland, sometimes on bare land, open land, even climbing trees. The species is common in waterlogged vegetation and on moist leaf litter. It is widely distributed in the state of Assam. It is distributed throughout Assam.

10. Hydrophylax leptoglossa

Assam Forest Frog (As: habi beng)

This is a medium-sized frog. Dorsally brown above with irregularly arranged small or large black spots or making. Limbs are with black cross bands. Hinder side of the thigh marbled with black and white. Two thick dorsolateral golden yellow fold extends from the corner of the eye to the groin are present. Ventrally the surface is white, spotted or marbled with black or brown.

The species inhabits swamps with thick vegetation. Males call from thick vegetation near a water body or vegetation mounds of submerged field. The species breed from April to June and lay their eggs in any available water bodies. The males used to call loud from swamps with thick vegetation and also from the bank hiding under the thicket.

11. Hylarana tytleri

Yellow Striped Frog (As:Chirkati beng)

Hylarana tytleri is a small size frog (SVL 32.00 mm). The fingers of the frog are free and toes are more than two-third webbed. The digital tips are swollen into a small pearshaped disc.  Dorsally skin is green or yellowish-green.  Dorso-lateral fold extends on each side from the back of the eye to groin, is yellow to cream in colour. The ventral surface is either light yellowish or white in colour.

Mostly found in pools, waterlogged rice fields, marshes, moist grasses and most commonly amongst aquatic vegetation. They stick to the grass blade vertically, also found in leaves of the water hyacinth. Males give low pitched whistling call from the vegetation of the waterlogged area. It is distributed widely in the state.